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 JUN 1 6 2005 
 
 UNiVERSJTYOHLUNOIS 
 
UNIVERSITY OF ILLINOIS .' - 
 
 Agricultural Experiment Station. 
 
 URBANA, JUNE, 1903. 
 
 BULLETIN No. 86. 
 
 CLIMATE OF ILLINOIS. 
 
 BY J. G. MOSIER, B. S., CHIEF ASSISTANT IN SOIL PHYSICS. 
 
 This state lies with its northern boundary 2V 5 south of the center of 
 the north temperate zone, while the southern extremity is only 13j 
 from the torrid zone. It extends over 5 of latitude, or about 380 
 miles. It is situated mostly in the belt of hot summers and cold winters, 
 but in the southern part the winters are temperate. The altitude of 
 the state above sea varies between 320 feet in the extreme southern part 
 to 1,257 feet in Jo Daviess County, the highest point in the state. The 
 Ozark Ridge, extending east and west across the southern end, reaches 
 a height of 1,046 feet in the northwest of Pope County. This range of 
 altitude is too small to affect the climate to any marked extent, although 
 the Ozark Ridge does seem to exert some influence over the rainfall. 
 
 The state lies entirely within the belt of prevailing westerly winds 
 with its accompanying cyclones and anticyclones. To these "lows" and 
 " highs," as they are commonly designated by the weather forecaster, is 
 due the peculiar climate of the state. Our weather changes are almost 
 entirely caused by the passage of these across the country, and their 
 importance requires more than a passing notice here. 
 
 CYCLONES, OR Lows; ANTICYCLONES, OR HIGHS. 
 A cyclone, or "low," is an area having an atmospheric pressure lower 
 than the normal, due to the rising of air in that locality. Throughout 
 this area the top of the column of mercury in the barometer (used in 
 
 45 
 
46 
 
 BULLETIN No. 86. 
 
 [June, 
 
 measuring the pressure of the air) is lower than normal, hence the word 
 " low. " A " high " is, of course, an area where the atmospheric pressure 
 is higher than normal and the term anticyclone is sometimes used to 
 mean the same thing. 
 
 Low pressure areas are very large whirlwinds from a few hundred to as 
 much as two thousand miles in diameter. These lows, or cyclones, are to 
 be distinguished from the small, very violent whirlwinds or tornadoes 
 that are so much dreaded. The term cyclone is very frequently erro- 
 neously applied to tornadoes but in the cyclone proper the wind rarely 
 attains a velocity sufficient to do much damage. The usual move- 
 ment of 03 clones is in an easterly direction, at from twenty to thirty 
 miles an hour. During the cooler season of the year they pass more 
 rapidly and are better defined than. in summer. 
 
1903.J . CLIMATE OF ILLINOIS. 47 
 
 The approach of a cyclone is usually indicated by the changing of 
 the wind to a southerly or an easterly direction, by the appearance of 
 white, stringy, or fibrous clouds, or by a general haziness that produces 
 a halo or circle around the sun or moon. 
 
 Plate I is a diagram of a " low " as it is represented on weather maps. 
 The large arrow represents the direction of movement. The heavy 
 curved lines are isobars and are drawn through places having the same 
 atmospheric pressure. The meaning of the term "low" may be read- 
 ily seen from this. The dotted lines are isotherms, or lines drawn 
 through places having the same temperature. Small arrows point in 
 the direction toward which the wind is blowing. The circles and letters 
 indicate the condition of the weather; as, o, clear; e, partly cloudy; 
 , cloudy.; R, rain; S, snow. 
 
 One of the most important and noticeable changes that occurs during 
 the passage of a cyclone is the shifting of the wind with its accompany- 
 ing change in temperature. Let us notice some of the changes that take 
 place as the different parts of the cyclone pass over different places. 
 Let us assume a place, so situated that the southern part of the storm 
 passes over it, along the line A B. (See Plate I.) 
 
 Since a cyclone is a whirling storm the wind will not blow directly in 
 toward the center of the low, but spirally, as could be shown by producing 
 one of the small arrows so as to have it approach the center forming a 
 spiral. At A in the "high," the wind will blow from the north, but 
 as the storm approaches it will shift to the south or southeast, and at 
 the same time the temperature will begin to rise. As the storm passes 
 eastward the wind will change to southwest, to west, and then to north- 
 west, and the temperature will become lower until 25 is reached at B. 
 If the storm pass over a place along the line C D, the wind will blow 
 from the southeast till the center of the storm is reached, when it will 
 suddenly change to the northwest with a lowering of temperature until 20 
 or lower is reached. If the northern part of the cyclone pass over a 
 place along the line E F, the wind will blow from an easterly direction, 
 but as the center of the storm passes to the south there will be a gradual 
 shifting of the wind to the north and northwest with a lowering of tem- 
 perature. The easterly winds of this part of the storm are usually 
 accompanied by cold, steady rains in the warmer seasons, and by heavy 
 snows in winter. The rainfall in the southeast part of a cyclone is usually 
 in the form of local showers, frequently very heavy. As a general thing, 
 little rain or snow falls after the center of the low is past and the wind 
 has shifted to the west or northwest. Clearing weather usually 
 follows the passage of the center, and the rear of the storm is marked 
 by cool, clear weather. The directions of the wind given above are 
 greatly modified by the fact that the cyclone frequently comes from the 
 northwest to about the Mississippi Valley and then turns to the northeast. 
 
48 
 
 BULLETIN No. 86. 
 
 [June, 
 
 SOURCES OF DATA. 
 
 The data for this bulletin was very largely obtained from the records 
 and publications of the Weather Bureau, and I desire to thank the 
 directors of the stations, and especially the Chief of the Weather Bureau, 
 for so kindly furnishing the data desired. The records for some of the 
 counties are fragmentary, and in many cases short, and eleven have no 
 records; but the records obtained are so well distributed that a good 
 average for the state, districts, and a very large number of counties 
 has been obtained. For counties without records the averages have 
 been obtained by taking the data from surrounding counties. In a few 
 cases records have been taken from stations just outside of the state, as 
 Dubuque, Davenport, and Keokuk, Iowa; Hannibal and St. Louis, 
 Missouri; Paducah, Kentucky; Vincennes and Terre Haute, Indiana; 
 and Beloit, Wisconsin. 
 
 DISTRICTS. 
 
 For convenience, the state has been divided into three districts, or 
 sections, the northern, central, and southern. The boundary between the 
 northern and central sections is formed by the county lines lying nearest 
 the parallel of 40 40 ' , and that between the central and southern sections 
 by the county lines nearest the parallel of 39. 
 
 TABLE 2. AVERAGE RAINFALL BY YEARS FOR THE DISTRICTS AND THE STATE 
 
 INCHES. 
 
 District. 
 
 1872. 
 
 1873. 
 
 1874. 
 
 1875. 
 
 1876. 
 
 1877. 
 
 1878. 
 
 1879. 
 
 1880. 
 
 1881. 
 
 1882. 
 
 Northern .... 
 Central 
 
 35.15 
 32.65 
 30.05 
 
 34.72 
 43.17 
 49.51 
 
 27.20 
 32.17 
 46.82 
 
 34.85 
 43.22 
 
 48.48 
 
 40.22 
 48.67 
 54.03 
 
 38.87 
 46.12 
 43.23 
 
 34.92 
 43.18 
 43.25 
 
 29.70 
 22.85 
 43.08 
 
 37.09 
 38.02 
 46.30 
 
 42.64 
 48.11 
 36.73 
 
 39.23 
 44.91 
 55.68 
 
 Southern .... 
 
 
 Av. for state . . 
 
 33.32 
 
 40.35 
 
 32.45 
 
 39.23 
 
 45.47 
 
 41.32 
 
 41.07 
 
 33.03 
 
 39.51 
 
 41.94 
 
 45.01 
 
 District. 
 
 1883. 
 
 1884. 
 
 1885. 
 
 1886. 
 
 1887. 
 
 1888. 
 
 1889. 
 
 1890. 
 
 1891. 
 
 1892. 
 
 1893. 
 
 Northern .... 
 Central. . . 
 
 40.72 
 43.40 
 51.93 
 
 40.07 
 39.56 
 47.55 
 
 38.56 
 40.93 
 41.34 
 
 28.88 
 36.12 
 38.54 
 
 31.36 
 33.27 
 34.64 
 
 31.77 
 41.51 
 42,13 
 
 31.27 
 36.80 
 40.96 
 
 34.09 
 32.82 
 48.68 
 
 21.46 
 31.09 
 36.10 
 
 41.35 
 41.27 
 39.78 
 
 29.90 
 39.94 
 41.40 
 
 Southern 
 
 
 Av. for state . . 
 
 45.06 
 
 42.32 
 
 40.02 
 
 34.01 
 
 32.71 
 
 38.21 
 
 35.88 
 
 38.33 
 
 29.62 
 
 40.02 
 
 34.11 
 
 District 
 
 1894. 
 
 1895. 
 
 1896. 
 
 1897. 
 
 1898. 
 
 1899. 
 
 1900. 
 
 1901. 
 
 1902. 
 
 Av. 
 
 Northern . . . 
 
 26.77 
 28.36 
 31.77 
 
 28.04 
 32.75 
 34.91 
 
 34.76 
 37.75 
 39.23 
 
 29.16 
 37.03 
 45.63 
 
 41.6529.03 
 45.2934.64 
 53.6238.91 
 
 34.33 
 35.09 
 
 38. 2C 
 
 22.95 
 26.19 
 30.34 
 
 47.22 
 41.56 
 35.03 
 
 33.48 
 38.01 
 42.19 
 
 Central 
 
 Southern 
 
 
 Average for state . . . 
 
 28.33 
 
 31.17 
 
 36.62 
 
 36.48 
 
 47.39 
 
 33.91 
 
 35.70 
 
 25.00 
 
 41.58 
 
 37.39 
 
1903.] 
 
 CLIMATE OF ILLINOIS. 
 
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 WWVERfiiTY OF ILLINOIS 
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52 
 
 BULLETIN No. 86. 
 
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1903.] 
 
 CLIMATE OF ILLINOIS. 
 
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 Alexander 
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 : : : :^: : : : : :g : g : 
 
54 
 
 BULLETIN No. 86. 
 
 [June, 
 
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1903.] 
 
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56 
 
 BULLETIN No. 86. 
 
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58 
 
 BULLETIN No. 86. 
 
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1903.] 
 
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60 
 
 BULLETIN No. 86. 
 
 [June, 
 
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1903.] CLIMATE OF ILLINOIS. 
 
 TABLE 4. AVERAGE MONTHLY RAINFALL IN INCHES. 
 
 61 
 
 District. 
 
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 1 97 
 
 1 94 
 
 2 7?, 
 
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 4 05 
 
 3 85 
 
 3 67 
 
 ? 97 
 
 3 ?1 
 
 2 04 
 
 ? ?3 
 
 1 81 
 
 Central 
 
 ?, 7,1 
 
 ? ?8 
 
 8 04 
 
 8 37 
 
 4 9.6 
 
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 3 53 
 
 2 69 
 
 3 ?7 
 
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 9 89 
 
 ? 94 
 
 Southern . . . 
 
 ?, 85 
 
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 4 4? 
 
 3 53 
 
 4 06 
 
 4 ?,Q 
 
 3 37 
 
 2 58 
 
 ? 74 
 
 2 25 
 
 3 57 
 
 2 80 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Average for State .-. 
 
 9 30 
 
 ? ?M 
 
 3 ?8 
 
 3 OS 
 
 4 13 
 
 4 10 
 
 3 54 
 
 ? 77 
 
 3 11 
 
 2 09 
 
 ? 8? 
 
 9 ??| 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 RAINFALL OF THE STATE. 
 
 NORTHERN DISTRICT.. The word rainfall, as used in this bulletin, 
 includes both rain and snow. The average for both state and districts 
 has been obtained from observations made since 1872 and extending over 
 a period of thirty-one years. The records previous to that date are too 
 fragmentary for calculating yearly averages. The average rainfall for the 
 northern district is 33.48 inches. Since 1872, thirteen years have been 
 below the normal, the lowest being 21.46 inches in 1891, and the next 
 22.95 inches in 1901. The greatest rainfall for thir district was in 1902, 
 47.22 inches and the next in 1898, 41.65 inches. Of the entire rainfall 
 about 17.4 percent falls in winter, 28.1 percent in spring, 31.9 percent in 
 summer-, and 22.6 percent in autumn. May is the wettest month, with 
 an average of 4.05 inches, and is followed by June, with 3.85 inches. 
 December has least rainfall, 1.81 inches. February and January coming 
 next with 1.94 and 1.97 inches. The rainfall is very irregular, as is 
 shown by Table 3. A month with a rainfall of not more than two 
 inches may usually be considered a dry month, especially in spring or 
 summer when the growing crops need a bountiful supply of moisture. 
 During the eighteen years that observations have been taken at Syca- 
 more, DeKalb County, seven Aprils, four Mays, and seven Junes have 
 had less than two inches of rainfall; that is, have been dry. 
 
 CEATRAL DISTRICT. The central district has an average rainfall of 
 38.01 inches. Since 1872, fifteen years have been below the average, 
 the lowest being 22.85 inches in 1879, the next, 26.19 inches in 1901. 
 
 The heaviest rainfall for this section was 48.67 inches in 1876 and the 
 next, 48.11, in 1881. About 18.8 per cent of the total rainfall occurs in 
 winter; 29.7 per cent in spring; 28.9 per cent in summer, and 22.6 percent 
 in autumn. May and June have the heaviest rainfall, 4.26 inches, and 
 4.22 inches. October has the least rainfall, 2.04 inches, while December, 
 January, and February have, respectively, 2.24, 2.27, and 2.28 inches. 
 In this section about one-fifth of the Aprils, Mays, and Junes are dry, 
 and about two-fifths of the Julys and Augusts. 
 
 SOUTHERN DISTRICT. The southern district has the greatest rainfall 
 of any part of the state, the average for the past thirty-one years being 
 
62 BULLETIN No. 86. [June, 
 
 42.19 inches, with seventeen years below normal. The least rainfall was 
 30.05 inches in 1872 and the next, 30.34 inches, in 1901. The greatest 
 rainfall was 55.68 inches in 1882 and the -next 54.03 inches in 1876. 
 About 21.6 per cent of the rain falls in December, January, and 
 February, 30.6 per cent in March, April, 'and May, 26 per cent in June, 
 July, and August, and 21.8 per cent in the autumn months. March is 
 the wettest month with an average of 4.42 inches. June is next with 4.29 
 inches. October has the least rainfall, 2.25 inches. Nearly one-sixth 
 of the months of April, May, and June have less than two inches of rain, 
 while about one-fifth of the months of July and August are dry. The 
 nature of the soil in this part of the state is such that a short drouth or a 
 heavy rainfall produces more injurious effects upon the growth of cereal 
 crops than in the central and northern parts of the state. 
 
 ENTIRE STATE. The average rainfall for the state is 37.39 inches. 
 The least was 25 inches in 1901, the next being 28.33 inches in 1894. 
 The greatest rainfall was in 1898, 47.39 inches, and the next was 45.47 
 inches in 1876; 1882 and 1883 had about 45 inches each. The six most 
 northern counties show an average of 11.3 inches less than the seven most 
 southern counties. 
 
 A peculiarity in the distribution of the rainfall in the southern part 
 of the state is due to the topography of that region. The Ozark Ridge, 
 spoken of before, extends across the northern parts of Union, Johnson, 
 Pope, and Hardin counties with an average altitude of about 800 feet. 
 This ridge causes a much heavier rainfall in these counties, amounting 
 to 7.15 inches more annually than in the counties immediately north 
 of the ridge. This difference is, of course, due to the greater condensa- 
 tion of the moisture as the south winds pass over this higher region. 
 Another rainy region occurs along the Wabash river extending north 
 into Crawford County, giving to the counties along the river about three 
 inches more rainfall than to those in the next tier west. 
 
 This is probably due to the break in the Ozark Ridge, through which 
 the Ohio River passes. The moisture is carried through this gap without 
 condensation, and is then rather uniformly distributed to the north. 
 It shows what the condition of southern Illinois would be without the 
 Ozark Ridge. A corresponding increase of rainfall, but not so noticeable, 
 is found along the Mississippi River as far north as Madison County. 
 
1903.] 
 
 CLIMATE OF ILLINOIS. 
 
 63 
 
 TABLE 5. AVERAGE TEMPERATURE, MONTHLY AND ANNUAL. 
 DEGREES FAHRENHEIT. 
 
 Counties. Northern District. 
 
 i 
 
 i- 
 
 1 
 
 s 
 
 s 
 
 i 
 
 & 
 
 S 
 
 I 
 
 i- 
 
 h 
 
 <-> 
 
 bC 
 
 Sj 
 
 1 
 
 t 
 O 
 
 & 
 
 
 
 4 
 
 (3 "* 
 3g 
 
 
 18.4 
 
 23.3 
 20.4 
 23.6 
 20.2 
 20.8 
 ?4 <1 
 
 20.8 
 
 21.7 
 20.4 
 24.8 
 21.9 
 21. 6 
 74 1 
 
 30.8 
 35.3 
 32.5 
 34.0 
 32.4 
 33.4 
 36.9 
 
 46.6 
 51.1 
 48.4 
 44.2 
 47.9 
 48.4 
 50.5 
 49.7 
 51.5 
 51.0 
 49.1 
 49.0 
 48.5 
 48.7 
 47.4 
 50.9 
 45.8 
 50.7 
 
 55.7 
 62.4 
 59.8 
 54.6 
 58.8 
 59.2 
 62.0 
 61.6 
 62.6 
 62.3 
 60.2 
 60.6 
 59.5 
 60.4 
 57.4 
 62.4 
 55.7 
 61 f. 
 
 67.0 
 72.2 
 68.9 
 66.9 
 68.9 
 69.2 
 71.6 
 70.9 
 71.3 
 71.1 
 70.5 
 69.0 
 69.8 
 70.1 
 69.2 
 70.9 
 65.1 
 71 7 
 
 72.1 
 76.0 
 73.6 
 72.5 
 72.6 
 73.6 
 76.9 
 75.4 
 75.5 
 75.3 
 74.8 
 77.1 
 74.2 
 73.3 
 72.4 
 75.1 
 70.5 
 75 7 
 
 69.8 
 73.5 
 70.7 
 71.1 
 69.7 
 71.8 
 73.6 
 72.6 
 73.2 
 73.8 
 71.6 
 71.8 
 71.9 
 71.3 
 69.4 
 73.1 
 69.5 
 7? 5 
 
 61.7 
 
 65.7 
 62.8 
 63.3 
 63.0 
 63.4 
 65.3 
 64.3 
 65.5 
 65.6 
 64.3 
 63.4 
 66.3 
 65.0 
 63.8 
 67.0 
 62.7 
 65.5 
 
 49 4 
 
 54.7 
 50.6 
 52.8 
 50.2 
 151.0 
 54.0 
 53.0 
 54.2 
 53.9 
 53.4 
 52.1 
 ,52A 
 50.6 
 48.0 
 53.8 
 49.9 
 53.8 
 
 33.9 
 38.1 
 3.5.2 
 38.5 
 34.6 
 36.2 
 40.1 
 39.4 
 38.4 
 37.0 
 39.7 
 35.4 
 36.3 
 35 7 
 34.4 
 39.0 
 35.8 
 38.9 
 
 22.0 
 25.7 
 2.5.2 
 28.1 
 28.2 
 26.4 
 29.5 
 30.2 
 31.5 
 26.8 
 29.1 
 34.4 
 25.8 
 30.4 
 27.4 
 24.3 
 29.0 
 29.0 
 
 45.7 
 50.0 
 47.4 
 47.9 
 47.4 
 47.9 
 50.8 
 50.0 
 50.5 
 49.6 
 49.7 
 48.9 
 48.4 
 48.8 
 47.6 
 49.8 
 46.9 
 50.3 
 48 4 
 50.6 
 45.7 
 51.0 
 49.4 
 48.2 
 50.8 
 49.4 
 48.9 
 49.4 
 47.0 
 50.5 
 47.8 
 49.7 
 47 
 51.8 
 
 
 Carroll 
 
 Cook 
 DeKalb 
 
 DuPage . 
 
 Ford 
 
 Grundy 
 
 24.0 
 23.3 
 22.3 
 24.8 
 19.2 
 20.3 
 22.4 
 19.7 
 24.5 
 23.5 
 23.4 
 
 23.2 
 22.1 
 20.9 
 23 1 
 21.5 
 22.5 
 22.9 
 22.1 
 21.4 
 23.1 
 ?4 9 
 
 35.6 
 36.6 
 35.5 
 36.0 
 33.4 
 33.6 
 35.5 
 40.0 
 35.5 
 32.2 
 35 9 
 
 Henderson 
 
 Henry 
 
 
 
 Kane 
 
 Kankakee 
 
 Kendall . 
 
 Knox 
 
 Lake 
 
 LaSallc 
 
 
 22.3ll9.6l33.8 
 
 48.8 
 49.9 
 46.3 
 52.4 
 48.1 
 49.7 
 53.4 
 50.9 
 45.2 
 50.9 
 47.0 
 51.5 
 49.3 
 50.0 
 
 60.8 
 60.6 
 57.9 
 62.0 
 61.4 
 60.3 
 63.6 
 59.6 
 61.0 
 61.8 
 58.5 
 62.6 
 60.5 
 61.8 
 
 69.9 
 70.5 
 66.4 
 71.4 
 70.8 
 68.0 
 74.3 
 70.9 
 70.5 
 71.0 
 69.0 
 71.3 
 69.9 
 71.0 
 69.0 
 73.1 
 
 74.6 
 75.8 
 71.8 
 76.5 
 75.4 
 74.3 
 78.3 
 74.1 
 75.3 
 75.2 
 73.3 
 75.5 
 74.1 
 74.8 
 73.3 
 77.8 
 
 72.5 
 72.7 
 69.5 
 73.3 
 73.0 
 72.5 
 74.8 
 72.4 
 72.6 
 72.8 
 70.9 
 73.2 
 71.5 
 72.4 
 70.9 
 74.8 
 
 64.4152.6 
 65.451.9 
 61.748.3 
 65.053.3 
 65.1 53.5 
 64.252.8 
 67.354.4 
 64.650.7 
 64.653.3 
 66.053.8 
 63.050.7 
 65.5 54.2 
 63.051.2 
 64.552 9 
 63.050.7 
 66.854.4 
 
 36.6 
 39.3 
 33.7 
 40.1 
 37.9 
 37.1 
 39.8 
 35.4 
 37.7 
 35.9 
 35.3 
 38.4 
 35.4 
 39.4 
 35 . 3 
 39.8 
 
 24.7 
 30.6 
 23.4 
 32.1 
 28.4 
 24.8 
 30.7 
 30.1 
 27.2 
 25.8 
 25.5 
 31.5 
 24.9 
 27.4 
 25.5 
 29.9 
 
 Livingston 
 
 25.4 
 18.5 
 26.6 
 21.8 
 21.0 
 24.6 
 21.6 
 21.7 
 22.7 
 19.1 
 23.3 
 19 4 
 ?3 ? 
 
 25.0 
 19.7 
 23.5 
 22.5 
 19.9 
 27.3 
 25.8 
 23.1 
 20.6 
 20.3 
 22.1 
 20.9 
 ?3 1 
 
 35.1 
 30.8 
 35.8 
 35.4 
 34.2 
 38.7 
 35.1 
 35.0 
 35.8 
 31.8 
 36.6 
 32 9 
 35.5 
 
 McHenry ' 
 
 Mercer 
 Ogle 
 
 Peoria 
 
 Putnam . . . 
 
 
 Stark 
 
 Stephenson 
 Warren 
 Whiteside 
 
 Will 
 
 Winnebago 
 
 19.1 
 24.6 
 
 20.3 
 26.1 
 
 31.8 
 38.0 
 
 47.0 
 52.8 
 
 58.5 
 63.6 
 
 Woodford ' ... 
 
 
 Counties. Central District. 
 
 9 
 
 >-> 
 
 f 
 
 (z* 
 
 1 
 
 
 
 < 
 
 h 
 
 oS 
 
 S 
 
 I 
 
 >-> 
 
 72.5 
 73.4 
 74.7 
 73.4 
 71.8 
 72.8 
 73.0 
 72.9 
 73.6 
 73.0 
 72.8 
 73.1 
 73.4 
 75.2 
 74.8 
 73.2 
 73.5 
 72.4 
 73.6 
 74.7 
 72.2 
 73.3 
 74.0 
 75.2 
 72.4 
 74.2 
 73.0 
 74.1 
 73.7 
 69.7 
 69.9 
 73.4 
 72.0 
 74.1 
 73.7 
 72.7 
 74.0 
 72.4 
 
 j*. 
 
 1-9 
 
 77.2 
 76.5 
 77.8 
 76.5 
 75.6 
 76.7 
 76.6 
 77.2 
 77.1 
 76.6 
 76.5 
 76.0 
 77.4 
 77.5 
 77.7 
 76.8 
 76.7 
 78.6 
 77.1 
 77.8 
 75.2 
 76.3 
 76.9 
 77.1 
 76.6 
 77.5 
 76.8 
 77.6 
 77.8 
 74.1 
 74.1 
 76.7 
 76.4 
 76.0 
 77.8 
 77.0 
 76.5 
 75.7 
 
 ti 
 3 
 
 75.3 
 74.5 
 75.5 
 74.5 
 73.0 
 74.9 
 74.7 
 74.7 
 74.9 
 74.7 
 74.1 
 74.5 
 75.0 
 76.0 
 75.6 
 75.6 
 74.3 
 74.6 
 74 9 
 75.5 
 73.5 
 75.0 
 76.3 
 76.3 
 73.1 
 75.9 
 74.4 
 76.9 
 76.9! 
 71.5; 
 71.4 
 75.2 
 73.9 
 74.0 
 76.9 
 74.8 
 73.9 
 73,4 
 
 fc 
 
 & 
 
 67.1 
 67.1 
 69.1 
 67.1 
 65.6 
 67.8 
 67.5 
 67.9 
 66.9 
 67.5 
 67.8 
 67.1 
 67.9 
 71.2 
 69.5 
 67.2 
 67.2 
 66.7 
 66.9 
 69.1 
 66.8 
 67.9 
 69.6 
 67.4 
 67.6 
 69.0 
 67.5 
 69.4 
 67.9 
 66.1 
 65.3 
 68.1 
 fifl.8 
 65.2 
 67.9 
 67.3 
 68.0 
 66.2 
 
 o 
 
 O 
 
 o 
 fc 
 
 4^1 
 
 Adams 
 
 28.2 
 27.5 
 31.0 
 27.5 
 25.5 
 28.2 
 29.6 
 28.4 
 30.2 
 29.6 
 26.3 
 27.9 
 27.6 
 29.8 
 29.4 
 26.3 
 27.0 
 24.7 
 30.2 
 31.0 
 27.7 
 27.5 
 29.7 
 25.4 
 25.0 
 27.8 
 26.8 
 30.8 
 29.0 
 25.3 
 25.2 
 28.2 
 26.4 
 26.7 
 29.0 
 25.8 
 27.0 
 26 4 
 
 25.9 
 27.0 
 30.9 
 27.0 
 25.9 
 28.7 
 30.5 
 30.2 
 30.4 
 30.5 
 25.2 
 24.8 
 27.7 
 27.7 
 28.9 
 22.5 
 29.4 
 24.0 
 30.4 
 30.9 
 27.3 
 25.6 
 28.9 
 23.3 
 24 8 
 27.7 
 27.7 
 28.2 
 26.6 
 24.4 
 24.0 
 26.8 
 29.4 
 26.4 
 26.6 
 29.2 
 28.5 
 26.9 
 
 38.5 
 37.5 
 41.5 
 37.5 
 37.6 
 38.3 
 40.4 
 40.0 
 42.6 
 40.4 
 39.1 
 39.2 
 38.1 
 42.1 
 41.5 
 37.8 
 39 . 
 37.5 
 42. G 
 41.5 
 38.7 
 40.2 
 41.2 
 38.6 
 38.0 
 39.9 
 39.5 
 41.3 
 39.9 
 37.1 
 36.3 
 39.8 
 39.2 
 38.5 
 39.9 
 38.9 
 39.4 
 38.6 
 
 52.3 
 54.1 
 55.1 
 54.1 
 51.2 
 53.3 
 54.2 
 53.6 
 54.1 
 54.2 
 52.6 
 52.5 
 52.0 
 55.7 
 55.4 
 52.8 
 55.4 
 52.5 
 54.1 
 55.1 
 52.7 
 53.3 
 54.6 
 53.3 
 52.0 
 53.4 
 53.4 
 54.6 
 52.7 
 50.5 
 50 . ?. 
 54.3 
 53.4 
 53.8 
 52.7 
 53.5 
 53.3 
 51.7 
 
 64.4 
 63.9 
 64.5 
 63.9 
 61.6 
 63.5 
 64.4 
 63.5 
 64.0 
 64.4 
 63.7 
 63.1 
 63.4 
 64.5 
 65.8 
 64.1 
 63.3 
 59.9 
 64.0 
 64.5 
 62.2 
 64.0 
 64.3 
 64.2 
 63.3 
 63.8 
 63.3 
 67.6 
 64.6 
 61.9 
 61.2 
 64.1 
 63.1 
 63.6 
 64.6 
 63.8 
 63.1 
 62.2 
 
 56.3 
 55.8 
 57.2 
 55.8 
 53.3 
 55.4 
 55.6 
 55.7 
 55.2 
 55.6 
 56.5 
 55.2 
 54.7 
 58.5 
 56.9 
 56.4 
 54.7 
 55.0 
 55.2 
 57.2 
 55.8 
 56.7 
 57.6 
 56.4 
 56.4 
 57.8 
 57.0 
 58.2 
 58.5 
 53.2 
 53.0 
 56.9 
 56.7 
 55.5 
 58.5 
 54.5 
 56.4 
 54,0 
 
 41.528.852.3 
 39.531.862.4 
 43.433.454.5 
 39.531.852.4 
 39.730.4:50.9 
 42.432.8 ! 52.9 
 41.537.453.8 
 42.5,32.653.3 
 42.833.353.8 
 41.537.4153.8 
 40.6 29.7 52.1 
 41.1 30.452.1 
 41.930.652.5 
 42.733.054.5 
 42.633.254.3 
 39.928.851.8 
 41.2 33.3 53.0 
 39.226.450.9 
 42.833.353.8 
 43.433.454.5 
 40.831.952.1 
 41.230.552.6 
 42.232.354.0 
 39.0)29.252.1 
 40.0128.951.5 
 40.831.553.3 
 41.031.852.7 
 43.831.5,54.5 
 43.0 29.753.3 
 39.928.650.2 
 38.328.451.3 
 40.431.452.9 
 41.4 32.0 52.5 
 39.431.952.1 
 43.029.753.3 
 41.533.252.6 
 40.1 31.752.6 
 39.730.251.4 
 
 Brown 
 
 Calhoun 
 
 Cass . . . ... 
 
 Champaign 
 Christian , . . . 
 
 Clark 
 Coles . 
 
 Crawford . . 
 
 Cumberland ... . 
 
 DeWitt 
 
 Douglas 
 
 Edgar 
 Effingham . ... 
 
 Fayette . . . 
 
 Fulton 
 
 Greene 
 
 Hancock. 
 
 
 Jersey 
 
 Logan 
 
 Macon . 
 
 Macoupin . . 
 
 McDonough 
 
 McLean 
 
 Mason . 
 
 Menard 
 Montgomery 
 
 Morgan ... . 
 
 Moultrie 
 Piatt . . 
 
 Pike 
 
 Sangamon . . 
 
 Schuyler 
 
 Scott .... 
 
 Shelby 
 Tazewell 
 
 Vermilion . . 
 
64 
 
 BULLETIN No. 86. 
 
 [June, 
 
 TABLE 5. AVERAGE TEMPERATURE, MONTHLY AND ANNUAL. 
 DEGREES FAHRENHEIT. Continued. 
 
 Counties. Southern District. 
 
 c 
 3 
 
 4 
 
 
 
 | 
 
 1 
 
 5 
 
 S 
 
 o 
 a 
 
 1 
 
 >> 
 
 i 
 
 M 
 < 
 
 I 
 
 "5 
 O 
 
 i 
 
 * 
 
 
 <0 
 
 Q 
 
 i* 
 3g 
 
 Alexander 
 
 35.4 
 29.2 
 29.9 
 30 5 
 32.3 
 
 38.4 
 29.8 
 32.3 
 30.0 
 30 1 
 
 46.8 
 41.0 
 40.8 
 41.7 
 43.5 
 
 55.2 
 55.2 
 55.1 
 54.9 
 55.7 
 
 65.4 
 66.5 
 63.6 
 66.4 
 66.4 
 
 75.6 
 74.5 
 73.2 
 74.5 
 75.1 
 
 79.1 
 
 77.7 
 76.4 
 
 77.8 
 78.4 
 
 74.2 
 75.5 
 74.3 
 75.9 
 76.8 
 
 70.6 
 68.4 
 67.7 
 68.9 
 69 3 
 
 58.9 
 56.0 
 54.9 
 
 50 . 8 
 57 2 
 
 46.7 
 42.5 
 42.9 
 42.9 
 44 5 
 
 39.4 
 33.9 
 35.5 
 33.9 
 33 9 
 
 57.1 
 54.2 
 53.9 
 54.5 
 55.3 
 
 Bond 
 
 Clay . . 
 
 Clinton 
 
 Edwards . 
 
 Franklin 
 
 33.3 
 34.6 
 32.5 
 35.5 
 32.7 
 32 9 
 
 33.5 
 33.5 
 34.3 
 34.0 
 33.3 
 30.6 
 33.2 
 30.8 
 31.1 
 32.6 
 35 9 
 
 44.7 
 44.7 
 42.9 
 45.5 
 45.8 
 43.1 
 46.3 
 40.7 
 41.1 
 41.6 
 49 
 
 56.6 
 56.1 
 56.0 
 57.3 
 58.1 
 54.4 
 57.8 
 55.3 
 55.3 
 56.3 
 59.1 
 
 66.7 
 66.5 
 64.9 
 67.2 
 68.4 
 66.3 
 68.6 
 65.8 
 65.4 
 64.8 
 69 9 
 
 75.6 
 76.0 
 74.8 
 76.3 
 77.5 
 75.2 
 76.4 
 75.5 
 73.4 
 75.3 
 78.5 
 
 78.8 
 78.9 
 78.2 
 79.7 
 79.2 
 78.2 
 79.9 
 78.4 
 77.4 
 77.7 
 81 6 
 
 77.2 
 77.9 
 75.9 
 79.7 
 78.7 
 76.9 
 79.2 
 75.6 
 74.8 
 73.2 
 80 8 
 
 69.5 
 71.2 
 69.1 
 66.4 
 70.2 
 69.9 
 72.5 
 69.7 
 68.4 
 66.9 
 74.0 
 
 57.3 
 57.6 
 56.7 
 59.2 
 58.0 
 58.6 
 60.0 
 56.8 
 55.7 
 55.2 
 62.0 
 
 45.1 
 46.6 
 44.7 
 47.2 
 44.1 
 43.2 
 48.1 
 43.7 
 42.5 
 41.4 
 48.1 
 
 36.4 
 35.9 
 37.1 
 38.1 
 36.5 
 33.5 
 36.4 
 35.3 
 34.6 
 36.3 
 39 2 
 
 56.2 
 56.6 
 55.6 
 57.2 
 56.9 
 55.2 
 57.9 
 54.9 
 54.0 
 54.4 
 59.6 
 
 Gallat in 
 
 Hamilton 
 
 Hardin 
 
 Jackson 
 
 . Johnson 
 
 36.0 
 31.4 
 28.3 
 31.3 
 37 4 
 
 Lawrence 
 
 Madison 
 
 Marion 
 
 Massac. 
 
 MOP roe . . . 
 
 32.4 
 32.9 
 35.3 
 35 4 
 
 32.8 
 31.4 
 35.2 
 38.4 
 32.8 
 32.1 
 33.2 
 33.5 
 33.0 
 31.9 
 31.2 
 30.1 
 34.2 
 31.5 
 
 43.5 
 44.1 
 42.2 
 46.8 
 43.5 
 42.6 
 43.3 
 44.7 
 45.0 
 43.2 
 43.2 
 43.5 
 44.2 
 45.9 
 
 56.3 
 55.4 
 58.1 
 55.2 
 56.3 
 54.9 
 56.5 
 56.1 
 56.8 
 55.0 
 54.8 
 55.5 
 56.6 
 53.1 
 
 65.5 
 67.2 
 67.0 
 65.4 
 65.5 
 65.3 
 65.8 
 66.5 
 67.4 
 65.2 
 65.4 
 66.3 
 66.6 
 68.7 
 
 74.1 
 75.8 
 76.2 
 75.6 
 74.1 
 75.3 
 75.4 
 76.0 
 75.1 
 74.9 
 73.5 
 74.7 
 76.6 
 72.3 
 
 77.4 
 78.2 
 79.4 
 79.1 
 77.4 
 78.1 
 79 
 78.9 
 79.0 
 77.9 
 77.1 
 77.9 
 79.0 
 80.0 
 
 75.7 
 77.9 
 78.0 
 71.0 
 75.7 
 75.8 
 78.7 
 77.9 
 77.9 
 76.6 
 76.1 
 76.7 
 77.8 
 79.3 
 
 69.3 
 71.1 
 71.5 
 70.6 
 69.3 
 69.0 
 69.8 
 71 2 
 71.6 
 68.9 
 69.3 
 69.5 
 71.7 
 72.0 
 
 59.5 
 59.3 
 62.5 
 58.9 
 59.5 
 56.0 
 57.1 
 57.6 
 61.0 
 56.5 
 57.3 
 57.9 
 57.9 
 60.9 
 
 44.4 
 46.2 
 47.0 
 46.7 
 44.4 
 43.4 
 43.1 
 46.6 
 47.5 
 44.4 
 43.3 
 45.1 
 45.0 
 48.4 
 
 34.6 
 33.3 
 38.9 
 39.4 
 34.6 
 35.6 
 34.9 
 35.9 
 35.1 
 34.1 
 35.6 
 33.8 
 36.3 
 35.8 
 
 55.4 
 56.1 
 57.6 
 56.9 
 55.4 
 54.9 
 55.6 
 56.6 
 56.8 
 55.1 
 54.9 
 55.3 
 56.7 
 56.9 
 
 Perry ... 
 
 Pope 
 
 Pulaski 
 
 Randolph .... . . . . 
 
 32.4 
 31.4 
 30.9 
 34.6 
 32.2 
 32.6 
 32.0 
 32.9 
 34.6 
 35.8 
 
 Richland . . 
 
 St. Clair 
 
 Saline 
 
 Union 
 
 Wabash 
 Washington 
 Wayne. . . 
 
 White 
 
 Williamson 
 
 
 
 TABLE 6. AVERAGE MONTHLY TEMPERATURE. 
 
 
 i 
 
 1-3 
 
 j 
 a 
 
 s 
 
 a 
 
 a 
 
 M 
 
 a 
 4 
 
 1 
 
 1 
 
 >f 
 i- 
 
 M 
 ^ 
 
 1 
 
 CO 
 
 to 
 
 O 
 
 i 
 
 & 
 
 o 
 
 V 
 
 o 
 
 &s 
 
 $ 
 
 Northern District 
 Central District 
 Southern District 
 
 22.1 
 27.8 
 32.9 
 
 22.7 
 27.4 
 32.8 
 
 34.7 
 39.4 
 43.8 
 
 49.5 
 53.4 
 56.0 
 
 60.3 
 63.7 
 66.4 
 
 70.0 
 73.2 
 75.2 
 
 74.6 
 76.7 
 78.5 
 
 76.6 
 
 72.1 
 74.7 
 76.6 
 
 74.4 
 
 64.5 
 67.6 
 69.9 
 
 50.7 
 56.0 
 58.4 
 
 37.2 
 41.2 
 44.7 
 
 27.8 
 31.5 
 35.8 
 
 48 9 
 52.7 
 55.9 
 
 Average for state 
 
 27.4 
 
 27.3 
 
 39.2 
 
 52.8 
 
 63.3 
 
 72.7 
 
 67.1 
 
 55.0 
 
 41.0 
 
 31.5 
 
 52.3 
 
 TEMPERATURE. 
 
 The state is subject to varying extremes of temperature in short 
 periods of time, due to the passage of cyclones, as has been already 
 explained. The average temperature for the state is 52.3 Fahrenheit. 
 There is a gradually increasing temperature from 46.9 in the northern 
 tier of counties to 57.6. in the southern, or a difference of 10.7. The 
 three summer months for the northern counties compared with the most 
 southern ones are about 7 cooler, while the winter months are about 
 17.2 cooler. The temperature is more uniform in the southern part, as 
 may be seen by comparing the average monthly temperatures for the 
 northern and southern districts. The differences between the January 
 temperatures of the two districts is 10.8, while for July it is only 3.9. 
 The average summer temperature for the northern district is 48 higher 
 than the winter, while in the southern part the summer is 44.4 higher 
 than the winter. 
 
1903.] CLIMATE OF ILLINOIS. v 65 
 
 NORTHERN DISTRICT. The average temperature for this district is 
 48.9. The coldest month is January, with an average of 22.1, while 
 February has 22.7. July has the highest average temperature, 74.6, or 
 52.5 above January. Boone and McHenry counties have the lowest 
 monthly average, 18.4 and 18.5. The lowest recorded temperature was 
 at Riley near Marengo in McHenry County, 31 below zero, in January, 
 1884, and at the same place, nineteen winters have had temperature of 
 20 or more below zero since 1870, and during every winter since that time 
 the temperature has been at least 10 below zero. The average of the 
 lowest temperatures observed at the different stations in 1884 was 25.6 
 below zero, and 1898 is the only year in which the average of the lowest 
 temperatures was higher than 10 below zero since 1872. The year 1875 
 shows the lowest annual temperature, 43.9, or 5 below normal. The 
 extreme range of 'temperature for this section is 143. The average 
 annual range is about 115, varying from 100 to 128. The seasonal 
 range of temperature varies with the season, the average being about 75 
 for winter and 53 for summer, the spring and fall months varying between 
 these. The highest temperature recorded was at Ottawa, 112 in 1901, 
 and this summer was the hottest shown by the records, not only of this 
 section, but of the central and southern sections. 
 
 CENTRAL DISTRICT. The records in this part of the state are not as 
 complete as for the northern part, very few extending as far back as 
 1882. The average temperature for this district is 52.7. - The extreme 
 range of temperature is 139. The average annual range is about 109, 
 varying from 95 to 130. The seasonal range is greater during winter, 
 being about 75, varying from 60 to 92, while for summer, the average 
 range is about 50, with a variation of from 40 to 68. The coldest 
 month is February, 27.4, with January 27.8, while the average for Decem- 
 ber is 31.5, or one-half degree below freezing. The lowest temperature 
 recorded in this region was in January, 1884, 28 below zero, and the 
 highest was 112 in 1901. The average of the lowest temperatures for 
 this district was 24.7 below zero in 1884, which was only about 1 above' 
 the same average for the northern district. At Springfield, since 1880, 
 only three winters show a temperature of 20 or more below zero, and 
 thirteen show 10 or more below. 
 
 SOUTHERN DISTRICT. The records for this district, with the exception 
 of Cairo and St. Louis, extend no further back than 1887. The average 
 temperature is 55.9. January and February have almost the same 
 average temperature, 32.9 and 32.8. No month in this section shows 
 . an average temperature below freezing. The lowest temperature ob- 
 served was in February, 1899, 23 below zero in Randolph County, while 
 the average lowest temperature for this year was 18.7 below. The 
 highest temperature recorded was in Marion County, 115 in July, 1901, 
 and at several places 112 and 113 were observed. The extreme range 
 
66 
 
 BULLETIN No. 86. 
 
 [June, 
 
 of temperature is 138, and an annual range of 128 has been known, 
 although the average is about 103. The winter range of temperature is 
 about 75, varying from 50 to 90, while the summer range is about 48, 
 with variations from 32 to 67. 
 
 FROST. 
 
 Data for the time of the last killing frost in spring and the first 
 in autumn have been collected and the average time of frost for each 
 district has been found and is shown in the accompanying table. 
 
 Districts. 
 
 Northern 
 Central 
 Southern . 
 
 Average date for 
 
 last killing 
 frost in spring. 
 April 29 
 April 21 
 April 14 
 
 Average date for 
 
 first killing 
 frost in autumn. 
 
 October 6 
 
 October 10 
 
 October 18 
 
 Days 
 
 between 
 
 killing frosts. 
 
 160 
 
 172 
 
 187 
 
 From the table we see that the season without injurious frosts is 
 nearly, two weeks longer in the central and four weeks in the southern 
 than in the northern section. The average length of time between 
 killing frosts in the northern tier of counties is 155 days, while that of 
 the seven southern counties is 195, or 40 days longer. Springfield gives 
 173 days between frosts, the average for spring and fall frosts being 
 April 24th and October 14th. This is about the average for the central 
 section. 
 
 TABLE 7. PERCENT OF TIME DURING WHICH THE WIND BLOWS FROM THE 
 DIRECTION INDICATED. 
 
 Districts. 
 
 December January, and February. 
 
 March, April, and May. 
 
 fc 
 
 
 VT 
 
 & 
 
 
 02 
 
 02 
 
 B 
 ad 
 
 B 
 
 B 
 fc 
 
 fe 
 
 & 
 fc 
 
 * 
 
 9.3 
 6.4 
 4.4 
 
 
 
 02 
 
 03 
 
 B 
 
 02 
 
 B 
 
 B 
 
 ^ 
 
 17.4 
 9.9 
 6.0 
 
 Northern 
 Central 
 Southern 
 
 2.4 
 1.7 
 15.3 
 
 45. 27.8 
 63.2 9.1 
 37.11 7.8 
 
 16.2 
 12.3 
 9.8 
 
 4.5 
 8.3 
 24 4 
 
 1.5 
 4.4 
 3.1 
 
 .3 
 .2 
 
 .8 
 
 1.8 
 .8 
 1.6 
 
 6.7 
 6.4 
 11.3 
 
 23.7 
 27.4 
 16.4 
 
 10.5 
 15.5 
 16.3 
 
 11.6 
 14.5 
 32.8 
 
 7.1 
 15.6 
 11.3 
 
 7.6 
 4.3 
 1.5 
 
 Districts. 
 
 June, July, and August. 
 
 September, October, and November. 
 
 fc 
 
 
 
 fc 
 
 
 
 & 
 to 
 
 OQ 
 
 B 
 ad 
 
 B 
 
 B 
 
 fc 
 
 K 
 
 
 
 fc 
 
 H 
 
 
 
 00 
 
 02 
 
 
 OQ 
 
 B 
 
 B 
 fc 
 
 4.1 
 2.1 
 3.2 
 
 Northern 
 Central 
 Southern 
 
 3.8 
 3.0 
 5.4 
 
 10.1 
 4.5 
 .8 
 
 5.135.5 15.3 
 1.443.521.7 
 1.834.440.6 
 
 8.0 
 10.7 
 6.7 
 
 8.5 13.5 
 3.012.0 
 2.2 8.1 
 
 3.1 19.2 
 2.819.6 
 8.4 13.9 
 
 10.5 
 4.2 
 3.0 
 
 28.624.5 
 27.626.3 
 17.242.3 
 
 8.2 1.6 
 16.8 .7 
 11.3 .7 
 
 YEARLY SUMMARY. 
 
 Districts. 
 
 * 
 
 
 fc 
 
 ^ 
 
 
 
 02 
 
 02 
 
 B 
 
 02 
 
 B 
 
 B 
 fc 
 
 Northern 
 
 4.1 
 
 23 9 
 
 12 8 
 
 24 3 
 
 14 3 
 
 6 2 
 
 4.7 
 
 9 4 
 
 Central . . . . ... 
 
 3 S 
 
 27.8 
 
 5 
 
 24.4 
 
 17.9 
 
 12.9 
 
 2 1 
 
 6 3 
 
 Southern .. 
 
 10 1 
 
 16 8 
 
 4 2 
 
 19 4 
 
 35 ?. 
 
 8 1 
 
 1 4 
 
 4 8 
 
1903.] CLIMATE OF ILLINOIS. 67 
 
 TABLE 8. AVERAGE HOURLY WIND VELOCITY IN MILES. 
 
 Stations. 
 
 a 
 I 
 
 j=> 
 j* 
 
 &H 
 
 C 
 
 03 
 S 
 
 a 
 < 
 
 i 
 
 
 
 1 
 
 1-5 
 
 >> 
 
 3 
 
 >-5 
 
 bb 
 
 < 
 
 *a 
 
 a. 
 
 $ 
 
 *j 
 
 o 
 
 O 
 
 g 
 
 fe 
 
 u 
 
 a> 
 Q 
 
 fe'SP 
 
 4 
 
 Chicago 
 
 13 ft 
 
 14 3 
 
 14 8 
 
 14 3 
 
 13 
 
 11 
 
 10 9 
 
 10 6 
 
 12 4 
 
 13 
 
 13 9 
 
 13 9 
 
 12 97 
 
 Davenport .... 
 
 8 ,ft 
 
 9 ? 
 
 10 3 
 
 10 6 
 
 9 
 
 7 4 
 
 6 4 
 
 6 
 
 7 ft 
 
 7 9 
 
 8 7 
 
 8 ft 
 
 8 33 
 
 Dubuque 
 
 ft 8 
 
 6 1 
 
 7 ? 
 
 7 ?! 
 
 6 ? 
 
 ,ft 4 
 
 4 7 
 
 4 4 
 
 5 2 
 
 ft 6 
 
 6 
 
 ft 6 
 
 5 8 
 
 Hannibal 
 
 9 6 
 
 10 
 
 11 fi 
 
 11 
 
 9 5 
 
 8 1 
 
 7 .ft 
 
 6 8 
 
 8 2 
 
 8 7 
 
 9 8 
 
 9 7 
 
 9 2 
 
 Keokuk 
 
 7 8 
 
 8 ?, 
 
 9 4 
 
 9 
 
 7 ft 
 
 6 ft 
 
 ft 9 
 
 ft 4 
 
 6 4 
 
 7 
 
 8 
 
 8 
 
 7 4 
 
 Springfield . . 
 
 10 1 
 
 10 7 
 
 11 3 
 
 10 6 
 
 8 7 
 
 7 4 
 
 6 7 
 
 6 ft 
 
 7 9 
 
 8 8 
 
 10 
 
 10 1 
 
 9.1 
 
 Cairo 
 
 8 6 
 
 9 3 
 
 10 5 
 
 9 4 
 
 7 6 
 
 fi ft 
 
 ft ft 
 
 ft 3 
 
 6 
 
 6 4 
 
 8 4 
 
 8 7 
 
 7 7 
 
 St. Louis. . . 
 
 11 ?, 
 
 11 4 
 
 ]?, 1 
 
 11 3 
 
 9 9 
 
 8 9 
 
 8 ? 
 
 8 1 
 
 8 fi 
 
 9 7 
 
 11 1 
 
 11 1 
 
 10.1 
 
 WIND. 
 
 DIRECTION AND VELOCITY. The state lies in the belt of prevailing 
 westerly winds in which the general atmospheric movement is from west to 
 east, yet the presence of the cyclones of this belt causes great variations, 
 both in the direction and velocity- of the wind. The wind direction has 
 been determined for seasons and not for months. The velocity is given 
 in miles per hour and was obtained from the published records of the 
 weather bureau stations within the state and the five along the Missis- 
 sippi River. The velocity was determined by the anemometer, but 
 comparisons are very difficult, because of the varying heights of the 
 instruments above the ground. At Chicago the anemometer is 274 feet 
 above the ground, at St. Louis 210, and at other stations as low as 79 
 feet. As a consequence, Chicago shows the highest wind velocity and St. 
 Louis next. The velocities given are taken from Davenport, Iowa, for the 
 northern district, Springfield for the central, and Cairo for the southern. 
 . The velocity of the wind is greater during the cooler months of the 
 year, February, March, and April being the windiest months, while July, 
 August, and September have the least atmospheric movement. The 
 season of this increased velocity is very significant to the agriculturist, 
 increasing, as it does, the amount of evaporation. In some cases the 
 soil may need to be dried and then it is a benefit. 
 
 The direction of the wind for the northern section is southerly for 
 45 percent of the time, while it blows from a north, northwest, and 
 west direction 41 percent of the time, giving a prevailing southerly 
 wind. In the central region the southerly wind blows for 55 percent of 
 the time while the colder winds from the north, northwest, and west 
 blow about 36 percent of the time. In the southern section the colder 
 winds blow for 31 percent, while the southerly winds blow for 62 percent 
 of the time. 
 
 1. WINTER MONTHS. During these months the northwest wind is 
 the most frequent in all sections of the state, blowing for 45 percent of 
 the time in the northern, 60 percent in the central, and 37 percent in the 
 southern district. In the northern section the west is next in frequency 
 
68 BULLETIN No. 86. [June, 
 
 to the northwest, while in the central the southwest wind, and in the 
 southern, the south wind are next in frequency. The east and northeast 
 winds are unimportant. The velocity of the winds is quite high, 
 being 8.7 miles an hour for the northern, 10.3 miles for the central, 
 exceeding slightly the velocity for the spring months, and 8.9 miles for 
 the southern section. This makes the winters of the central section 
 slightly more disagreeable than those of the other sections. 
 
 2. SPRING MONTHS. During this period the northwest wind is most 
 frequent in the northern and central sections, while the south wind blows 
 for about one-third of the time in the southern part. The northeast 
 and east winds assume some importance during these and the summer 
 months, owing probably to the courses of the low areas being farther south 
 and bringing the state, and especially the northern and central parts of 
 the state, oftener into the northern part of cyclones where the easterly 
 winds prevail. The southerly winds blow for about 35 percent of the 
 time in the northern part, 45 percent in the central, and about 60 per- 
 cent in the southern. The velocity of the wind is at its highest during 
 these months, the average in the northern part being 10 miles an hour, in 
 the central 10.2 miles, and in the southern 9.2 miles. April has the 
 highest velocity in the northern part, and March in the central and south- 
 ern, being 10.6 miles, 11.3 miles, and 10.5 miles for the different sections. 
 These high winds are apt to have a bad effect upon the unworked soils 
 rendering them cloddy, especially during the frequent dry spells of spring. 
 
 3. SUMMER MONTHS. During this time the southwest forms the 
 most frequent wind in the northern section, occurring 35^ percent of the 
 time, and also for the central part, occurring 43^ percent of the time. 
 In the southern part the south wind is prevalent for 40J percent of the 
 time with the southwest 34 percent. In each division the east and north- 
 east winds are still important. The southerly winds are prevailing ones 
 during these months, blowing 59 percent of the time in the northern 
 district, 76 percent in the central, and 82 [percent in the southern. 
 The velocity of the wind is least during the summer, being about 6.6 miles 
 an hour in the northern part, 6.9 miles in the central, and 5.8 miles in 
 the southern. August shows the least atmospheric movement of any 
 month during the year. 
 
 4. AUTUMN MONTHS. The northwest wind becomes more frequent 
 during this time, but the same ones are predominant as in summer. The 
 northeast winds have become less frequent until they blow only 4 per- 
 cent, 2 percent, and 3 percent in the north, center, and south, respec- 
 tively. The southerly winds occur for 61 per cent of the time in the 
 northern part, 71 per cent in the central, and 70 per cent in the southern. 
 The velocity of the wind increases during this time until it becomes 8 
 miles for the northern, 8.9 miles for the central, and 7 miles for the 
 southern part. 
 
1903.] 
 
 CLIMATE OF ILLINOIS. 
 
 69 
 
 TABLE 9. DAYLIGHT CLOUDINESS IN PERCENT. 
 NORTHERN DISTRICT. 
 
 Station. 
 
 c3 
 Hj 
 
 .0 
 V 
 ft 
 
 i* 
 
 a. 
 <J 
 
 ft 
 
 s 
 
 a5 
 d 
 
 >-> 
 
 3 
 
 -s 
 
 ti 
 
 2 
 < 
 
 49 
 
 OH 
 <l> 
 
 02 
 
 -ij 
 o 
 
 
 
 > 
 o 
 K 
 
 6 
 
 
 
 a 
 
 i 
 
 << * 
 
 Chicago 
 
 60 
 
 57 
 
 57 
 
 50 
 
 49 
 
 46 
 
 36 
 
 4? 
 
 43 
 
 48 
 
 59 
 
 61 
 
 51 
 
 Davenport .... 
 Dubuque 
 
 54 
 51 
 
 56 
 
 54 
 
 58 
 55 
 
 55 
 53 
 
 52 
 52 
 
 50 
 50 
 
 42 
 41 
 
 43 
 
 42 
 
 44 
 45 
 
 46 
 
 48 
 
 56 
 54 
 
 58 
 59 
 
 51 
 52 
 
 Average 
 
 55 
 
 56 
 
 57 
 
 53 
 
 51 
 
 49 
 
 40 
 
 4? 
 
 44 
 
 I 47 
 
 56 
 
 59 
 
 51 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 CENTRAL DISTRICT. 
 
 Hannibal 
 Keokuk 
 
 52 
 47 
 
 54 
 
 48 
 
 58 
 53 
 
 53 
 
 49 
 
 45 
 45 
 
 42 
 43 
 
 35 
 35 
 
 33 
 33 
 
 38 
 36 
 
 38 
 36 
 
 51 
 
 46 
 
 56 
 51 
 
 46 
 44 
 
 Springfield .... 
 
 56 
 
 57 
 
 60 
 
 56 
 
 53 
 
 54 
 
 43 
 
 40 
 
 41 
 
 41 
 
 53 
 
 60 
 
 51 
 
 Average . 
 
 52 
 
 53 
 
 57 
 
 53' 
 
 48 
 
 46 
 
 38 
 
 35 
 
 38 
 
 38 
 
 50 
 
 56 
 
 47 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 SOUTHERN DISTRICT. 
 
 Cairo 
 
 59 
 
 59 
 
 57 
 
 54 
 
 51 
 
 5? 
 
 45 
 
 41 
 
 4? 
 
 40 
 
 ^5 
 
 60 
 
 51 
 
 St. Louis 
 
 51 
 
 54 
 
 50 
 
 48 
 
 46 
 
 41 
 
 37 
 
 38 
 
 36 
 
 36 
 
 48 
 
 47 
 
 45 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Average 
 
 55 
 
 56.5 
 
 53.5 
 
 51 
 
 43.5 
 
 46.5 
 
 41 
 
 39.5 
 
 39 
 
 38 
 
 51.5 
 
 58.5 
 
 48 
 
 TABLE 10. SHOWING WHAT PERCENT THE ACTUAL SUNSHINE is OF THE POSSIBLE 
 SUNSHINE OF THE PLACE. 
 CHICAGO. 
 
 ' 
 
 a 
 a 
 
 "9 
 
 X> 
 g 
 A 
 
 M 
 
 03 
 
 S 
 
 E- 
 <; 
 
 >> 
 
 03 
 S 
 
 o 
 
 a 
 
 1-5 
 
 >> 
 
 i-s 
 
 bb 
 
 < 
 
 "a. 
 
 
 
 -ij 
 
 o 
 
 O 
 
 O ' 
 
 to 
 
 d 
 a> 
 
 Q 
 
 !& 
 
 4> 
 
 1894 
 
 57 
 
 57 
 
 5? 
 
 64 
 
 62 
 
 71 
 
 85 
 
 73 
 
 70 
 
 43 
 
 37 
 
 45 
 
 60 
 
 1895 . . 
 
 46 
 
 67 
 
 68 
 
 68 
 
 73 
 
 83 
 
 82 
 
 79 
 
 86 
 
 77 
 
 41 
 
 28 
 
 66 
 
 1896 . 
 
 35 
 
 55 
 
 65 
 
 63 
 
 78 
 
 84 
 
 66 
 
 8? 
 
 56 
 
 63 
 
 36 
 
 28 
 
 59 
 
 1897 
 
 38 
 
 31 
 
 50 
 
 49 
 
 62 
 
 52 
 
 59 
 
 54 
 
 71 
 
 72 
 
 32 
 
 30 
 
 50 
 
 1898 
 
 48 
 
 44 
 
 57 
 
 54 
 
 57 
 
 50 
 
 76 
 
 63 
 
 58 
 
 26 
 
 49 
 
 51 
 
 53 
 
 1899 
 
 49 
 
 4?: 
 
 32 
 
 65 
 
 61 
 
 71 
 
 66 
 
 75 
 
 54 
 
 51 
 
 38 
 
 37 
 
 53 
 
 1900 . 
 
 37 
 
 47 
 
 41 
 
 61 
 
 56 
 
 63 
 
 60 
 
 60 
 
 57 
 
 66 
 
 40 
 
 38 
 
 52 
 
 1901 
 
 40 
 
 67 
 
 36 
 
 67 
 
 50 
 
 69 
 
 77 
 
 56 
 
 67 
 
 69 
 
 52 
 
 40 
 
 58 
 
 1902 . 
 
 61 
 
 58 
 
 56 
 
 67 
 
 65 
 
 58 
 
 59 
 
 67 
 
 48 
 
 67 
 
 41 
 
 33 
 
 57 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Average 
 
 46 
 
 5? 
 
 51 
 
 6? 
 
 62 
 
 67 
 
 70 
 
 68 
 
 63 
 
 59 
 
 44 
 
 37 
 
 56 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ST. LOUIS. 
 
 1894 . . . 
 
 
 63 
 74 
 50 
 48 
 63 
 49 
 58 
 51 
 
 75 
 
 69 
 58 
 46 
 52 
 71 
 49 
 51 
 
 71 
 72 
 52 
 65 
 68 
 64 
 67 
 
 66 
 80 
 74 
 75 
 68 
 72 
 70 
 61 
 
 91 
 72 
 71 
 69 
 80 
 61 
 78 
 60 
 
 82 
 61 
 72 
 81 
 75 
 75 
 .79 
 75 
 
 83 
 76 
 81 
 81 
 76 
 80 
 75 
 52 
 
 76 
 
 82 
 60 
 90 
 
 82 
 65 
 78 
 57 
 
 71 
 79 
 79 
 
 88 
 72 
 67 
 75 
 69 
 
 64 
 51 
 46 
 52 
 50 
 58 
 80 
 38 
 
 56 
 48 
 57 
 29 
 49 
 51 
 44 
 38 
 
 69 
 64 
 ~64 
 65 
 64 
 68 
 57 
 
 1895 
 
 62 
 48 
 56 
 50 
 57 
 64 
 70 
 
 1896 . 
 
 1897 
 
 1899 
 
 1900 
 
 1901 
 
 1902 . 
 
 
 Average . . . .1. . 
 
 58 
 
 57 
 
 59 
 
 66 
 
 71 
 
 73 
 
 75 
 
 75 
 
 74 
 
 75 
 
 55 
 
 46 
 
 65 
 
 
 KEOKUK. 
 
 1901 
 
 56 
 
 63 
 
 70 
 61 
 
 36 
 
 39 
 
 54 
 65 
 
 62 
 54 
 
 63 
 40 
 
 73 
 
 59 
 
 75 
 50 
 
 67 
 55 
 
 65 
 
 70 
 
 69 
 
 36 
 
 38 
 34 
 
 61 
 52 
 
 1902 
 
 SPRINGFIELD. 
 
 1902 
 
 59 
 
 53 
 
 47 
 
 63 
 
 62 
 
 58 
 
 76 
 
 62 
 
 53 
 
 66 
 
 42 
 
 35 
 
 56 
 
 
70 BULLETIN No. 86. [June, 
 
 CLOUDINESS AND SUNSHINE. 
 
 For many years the weather bureau has been collecting data that 
 will give a close estimate of the daylight cloudiness. Table 9 gives 
 the results of these observations expressed in per cent. November, 
 December, January, February, March, and April are the cloudy months of 
 the year. The northern part is cloudy during 56 percent of the day- 
 light, the central and southern about 53 J percent ; or in other words, the 
 northern section has about five more cloudy days than the other sections 
 during the months named above. The percent of cloudiness is much 
 less for the other months of the year, the northern having 45J percent, 
 the central 40^ percent, and the southern 42 percent. A large amount 
 of cloudiness is not necessarily accompanied by a heavy rainfall, but 
 cloudy, and consequently cooler weather is very important in the develop- 
 ment of some crops. December is the cloudiest month of the year for 
 the northern and southern parts, and March for the central, although 
 December is only 1 percent less. July is the clearest month for the north- 
 ern, August for the central, and October for the southern part, with July 
 and August only 1 percent less. Table 10 gives the percent of sunshine 
 at some of the stations. At Chicago the sun shines 56 percent of the 
 time that it is possible for it to shine. At St. Louis the average sunshine 
 is about 65 percent. At Keokuk and Springfield the sunshine recorders 
 have been' installed but a short time, so that no average can be given as 
 yet. It is interesting to compare the sunshine records for 1901 , a very 
 dry year, with those for 1902, one of excessive rainfall. 
 
 GENERAL SUMMARY. 
 
 The succession of weather changes is due almost entirely to the pas- 
 sage of cyclones and anticyclones, or lows and highs. 
 
 The approach of a cyclone is usually indicated by the changing of the 
 wind to a southerly or an easterly direction and a circle around the sun 
 or moon. 
 
 If the southern part of a cyclone pass over a place the wind will 
 at first be from the southeast or south, and will gradually shift around 
 to the southwest, west, and northwest accompanied by a lowering of tem- 
 perature. The rain will come in showers. 
 
 If the center of the cyclone pass over a place there will be a sudden 
 shifting of the wind from a southerly to a northwest direction as the 
 center of the storm is passed. The rainfall may be either showers or 
 steady rain. 
 
 If the north part of the storm pass over a place the wind will blow 
 from an easterly direction and will shift through the north to the north- 
 west, with lowering of temperature. The rain will be a cold, steady 
 rain, if in the warmer months, and snow, if in winter. 
 
1903.] CLIMATE OF ILLINOIS. 71 
 
 The rainfall for the northern district is 33.48 inches, the least being 
 21.46 inches in 1891, the greatest being 47.22 inches. 
 
 Seventeen and four- tenths percent of the rain falls in winter, 28.1 
 percent in spring, 31.9 percent in summer, and 22.6 percent in autumn. 
 May is the wettest month. 
 
 The rainfall of the central district is 38.01 inches. The least rainfall 
 was 22.85 inches in 1879, the greatest, 48.67 inches, in 1876. . Eighteen 
 and eight-tenths percent of the total rainfall occurs in winter, 29.7 
 percent in spring, 28.9 percent in summer, and 22.6 percent in autumn. 
 May has heaviest rainfall. 
 
 The rainfall of the southern district is 42.19 inches. The least was 
 30.05 inches in 1872, the greatest, 55.68 inches, in 1882. About 21.6 
 percent falls in winter, 30.6 percent in spring, 26 percent in summer, and 
 21.8 percent in autumn. March has most rain. 
 
 The average rainfall for the state is 37.39 inches. The least was 
 25 inches in 1901, the greatest, 47.39 inches, in 1898. Six northern 
 counties have 11.3 inches less than seven southern counties. The Ozark 
 Ridge in the southern part of the state makes the rainfall of the counties 
 in which it is situated 7.15 inches more than those immediately above 
 the ridge. A rainy region is situated along the Wabash River up as 
 far as Crawford County. The average temperature for the state is 
 52.3 F. Northern tier of counties 46.9, southern counties 57.6. 
 Northern summers are 7 cooler than southern, while northern winters 
 are 17.2 cooler. 
 
 The average temperature for the northern district is 48.9. January 
 is the coldest month, 22.1, July is the hottest, 74.6. Lowest tempera- 
 ture recorded 31 below zero. The extreme range of temperature is 
 143, average annual range about 115. Highest temperature in summer 
 of 1901. 
 
 The average temperature for the central district is 52.7, the extreme 
 range being 139; the average annual range being about 109. Lowest 
 temperature recorded was 28 below zero in 1884, highest 112 in 
 1901. 
 
 The average temperature for the southern district, 55.9. Lowest 
 temperature observed was 23 below zero^ in February, 1899, the highest 
 being 115 in 1901. Extreme range is 138, with average annual range 
 about 103. 
 
 The average date for the last killing frost in spring is 15 days later 
 in northern than in southern part, and the date for the first killing frost 
 in fall is 12 days earlier than in the southern. The difference between 
 dates of last killing and first killing frosts for extreme parts of state 
 is 40 days. 
 
 November, December, January, February, March, and April are the 
 cloudy months of the year, being cloudy for 56 percent of the daylight 
 
72 
 
 BULLETIN No. 86. 
 
 [June, 
 
 in the northern, 53 in each of the other sections. The other months of 
 the year are less cloudy, having 45^' percent in the northern, 40^ in the 
 central, and 42 percent in the southern. December is the cloudiest month 
 for the northern and southern parts, and March for the central part. 
 
 METEOROLOGICAL SUMMARY FOR THE EXPERIMENTAL STATION. 
 
 1889. 
 
 TEMPERATURES. 
 
 Rainfall 
 in 
 inches. 
 
 Rela- 
 tive 
 humid- 
 ity. 
 
 Prevailing 
 wind, 
 directions. 
 
 No. of 
 clear 
 days. 
 
 No. of 
 partly 
 cloudy 
 days. 
 
 No. of 
 cloudy 
 days. 
 
 12 
 4 
 6 
 4 
 6 
 4 
 3 
 
 8 
 4 
 14 
 
 8 
 
 Max. 
 
 Min. 
 
 Mean. 
 
 Jan 
 
 57 
 53 
 72 
 75 
 91 
 88 
 90.5 
 89 
 87.5 
 82 
 62 
 66 
 
 -2 
 -7.5 
 18 
 25 
 28 
 40 
 50 
 29.5 
 32 
 25 
 4 
 15 
 
 29.28 
 23.36 
 39.92 
 51.9 
 59.2 
 65.5 
 72.7 
 69.2 
 61.32 
 47.26 
 36.82 
 42.71 
 
 1.48 
 2.08 
 1.61 
 .61 
 5.52 
 6.81 
 5.81 
 0.60 
 2.74 
 1.42 
 4.38 
 1.82 
 
 79.1 
 78.7 
 78.5 
 69.7 
 74.9 
 79.3 
 80.0 
 78.2 
 80.1 
 75.2 
 83.4 
 82.6 
 
 S. W. 
 S. W. & n. W. 
 n. w. 
 n. e. & n. w. 
 
 s. w. 
 s. w. 
 s. 
 s. 
 s. w. 
 n. w. 
 n. w. 
 s. w. 
 
 6 
 
 7 
 10 
 8 
 1 
 4 
 8 
 
 1 
 15 
 6 
 
 8 
 
 13 
 
 ,17 
 
 15 
 
 18 
 24 
 22 
 20 
 
 is 
 
 12 
 10 
 15 
 
 Feb . . 
 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct. . 
 
 Nov 
 Dec 
 
 Totals . . . 
 
 
 
 
 34.88 
 
 
 y 
 
 80 
 7.3 
 
 177 
 16.1 
 
 7a 
 
 6.6 
 
 Average . 
 
 76 
 
 21 
 
 49.9 
 
 2.91 
 
 78.3 
 
 s. w. 
 
 1890. 
 Jan 
 
 66 
 68 
 61 
 81 
 83 
 96 
 97.5 
 96 
 89 
 76 
 68 
 58 
 
 -5 
 
 7 
 2 
 29 
 33 
 47 
 45 
 44.5 
 33 
 27 
 21 
 8 
 
 33.5 
 34.66 
 33.35 
 52.32 
 58.27 
 74.56 
 73.02 
 68.74 
 60.46 
 52.07 
 42.62 
 30.91 
 
 5.26 
 1.87 
 2.70 
 4.11 
 3.56 
 3.80 
 2.83 
 1.93 
 1.19 
 2.35 
 1.63 
 .05 
 
 88.0 
 85.6 
 79.2 
 73.1 
 72.2 
 77.4 
 77.9 
 71.9 
 76.8 
 79.2 
 74.6 
 75.1 
 
 n. w. 
 s. w. & n. w. 
 n. w. 
 n. e. 
 s. w. 
 s. w. 
 n. e. 
 n. w. 
 n. e. 
 n. w. 
 n. w. 
 n. w. 
 
 6 
 6 
 8 
 10 
 14 
 13 
 17 
 15 
 6 
 3 
 10 
 7 
 
 15 
 12 
 16 
 15 
 14 
 16 
 13 
 15 
 20 
 21 
 12 
 17 
 
 10 
 10 
 7 
 5 
 3 
 1 
 1 
 1 
 4 
 7 
 8 
 7 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct 
 Nov 
 Dec 
 
 Totals . . . 
 
 
 
 
 31.28 
 
 
 
 115 
 9.7 
 
 186 
 15.5 
 
 64 
 15.3 
 
 Average . 
 
 78.2 
 
 24.6 
 
 51.2 
 
 2.6 
 
 77.6 
 
 n. w. 
 
 1891. 
 Jan. . 
 
 57 
 61 
 65 
 81 
 91 
 93 
 93 
 99 
 96 
 88.5 
 67 
 60 
 
 6 
 -9 
 -1 
 22 
 30 
 49 
 42 
 40 
 41 
 27 
 2 
 11 
 
 30.26 
 30.45 
 32.55 
 52.78 
 58.4 
 71.9 
 70.12 
 70.21 
 69.2 
 51.3 
 35.69 
 37 
 
 0.99 
 
 2.60 
 3.55 
 3.54 
 0.89 
 2.08 
 1.41 
 2.86 
 .41 
 1.29 
 5.58 
 1.53 
 
 84.7 
 81.5 
 84.9 
 79.5 
 70.0 
 78.5 
 79.6 
 74.0 
 66.0 
 72.9 
 83.1 
 79.2 
 
 s. w. 
 n. w. 
 n. e. & n. w. 
 n. w. 
 n. e. 
 s. w. 
 s. w. 
 n. w. 
 s. 
 s. 
 s. 
 s. 
 
 6 
 6 
 4 
 8 
 12 
 9 
 11 
 2 
 6 
 13 
 6 
 8 
 
 10 
 11 
 16 
 18 
 14 
 15 
 18 
 27 
 23 
 17 
 13 
 17 
 
 15 
 11 
 11 
 4 
 5 
 6 
 2 
 2 
 1 
 1 
 11 
 6 
 
 Feb 
 March . .. 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct. 
 
 Nov. 
 
 Dec 
 Totals . . . 
 
 
 
 
 26.73 
 
 
 
 92 
 7.6 
 
 199 
 16 
 
 75 
 6.1 
 
 Average . 
 
 79.3 
 
 21 
 
 50.82 
 
 2.22 
 
 77.8 
 
 s., s. w. 
 
1903.] 
 
 CLIMATE OF ILLINOIS. 
 
 73 
 
 METEOROLOGICAL SUMMARY FOR THE EXPERIMENT STATION Continued. 
 
 1892. 
 
 TEMPERATURES. 
 
 Rainfall 
 in 
 inches. 
 
 Rela- 
 tive 
 humid- 
 ity. 
 
 Prevailing 
 wind, 
 directions. 
 
 No. of 
 clear 
 days. 
 
 No. of 
 partly 
 cloudy 
 days. 
 
 No. of 
 cloudy 
 days. 
 
 Max. 
 
 Min. 
 
 Mean. 
 
 Jan. . 
 
 57 
 55 
 69 
 70.5 
 82 
 94 
 96.5 
 94 
 87 
 88.5 
 64 
 60 
 
 -15 
 
 *. 
 * 
 
 26" 
 36 
 51 
 46 
 
 47 
 42 
 19 
 
 7 
 _7 
 
 19.2 
 33 
 36.1 
 48.6 
 57.9 
 70.6 
 73.3 
 71.5 
 63.9 
 53.6 
 34.8 
 27.7 
 
 0.79 
 2.64 
 2.59 
 6.45 
 7.86 
 5.36 
 2.50 
 2.45 
 0.93 
 0.93 
 4.95 
 1.62 
 
 82.9 
 87.6 
 82.1 
 77.4 
 81.1 
 82.1 
 80.4 
 81.1 
 76.3 
 70.5 
 83.7 
 86.7 
 
 s. 
 s. 
 s. w. 
 n. w. 
 s. w. 
 s. w. 
 s. 
 w. 
 s. 
 s. 
 s. 
 s. 
 
 6 
 2 
 3 
 3 
 1 
 8 
 4 
 10 
 14 
 9 
 7 
 4 
 
 20 
 14 
 22 
 24 
 23 
 20 
 24 
 18 
 15 
 20 
 16 
 16 
 
 5 
 13 
 6 
 3 
 7 
 2 
 3 
 3 
 1 
 2 
 7 
 11 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Totals . . . 
 
 
 
 
 39.05 
 
 
 - 
 
 71 
 5.9 
 
 232 
 19.3 
 
 63 
 5.3 
 
 Average . 
 
 76.4 
 
 
 49.1 
 
 3.25 
 
 81.0 
 
 s. 
 
 
 1893. 
 Jan. . 
 
 48 
 51 
 76 
 75 
 84 
 93 
 98 
 96 
 97 
 84 
 75 
 63 
 
 *. 
 *. 
 *'. '. 
 30" 
 37 
 53 
 48 
 37 
 31 
 18 
 6 
 -6 
 
 14.8 
 25.8 
 37.8 
 49.3 
 57.4 
 70.5 
 76.4 
 71.1 
 66.5 
 53.3 
 37.3 
 30 
 
 1.05 
 4.48 
 3.20 
 7.68 
 4.83 
 1.55 
 .59 
 .06 
 3.62 
 1.14 
 2.98 
 1.09 
 
 86.1 
 87.5 
 79.6 
 76.0 
 75.6 
 70.5 
 71.9 
 66.8 
 58.6 
 77.4 
 84.8 
 84.4 
 
 n. w. 
 n. w. 
 
 s. 
 s. 
 n. & s. w. 
 s. 
 s. 
 n. 
 w. 
 s. 
 s. 
 s. 
 
 4 
 5 
 2 
 1 
 4 
 6 
 1 
 11 
 4 
 9 
 6 
 
 
 17 
 14 
 22 
 19 
 24 
 18 
 29 
 19 
 19 
 18 
 16 
 18 
 
 10 
 9 
 7 
 10 
 3 
 6 
 1 
 1 
 7 
 4 
 8 
 13 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Totals . . . 
 
 
 
 
 32 37 
 
 
 
 53 
 
 4.4 
 
 223 
 19 
 
 79 
 6.5 
 
 Average . 
 
 78 
 
 
 49.1 
 
 2.69 
 
 76.6 
 
 s. 
 
 
 1894. 
 Jan. . 
 
 64 
 58 
 77 
 85 
 89 
 97 
 98 
 99 
 94 
 84 
 67 
 59 
 
 -21 
 -5 
 10 
 25 
 32 
 34 
 47 
 41 
 38 
 28 
 12 
 -4 
 
 29.4 
 24.7 
 43.5 
 51.4 
 59.6 
 73.4 
 73.8 
 72.3 
 65 
 51.9 
 35.9 
 32.9 
 
 1,95 
 1.32 
 2.41 
 1.86 
 3.32 
 1.78 
 1.08 
 2.06 
 4.21 
 .51 
 2.77 
 1.44 
 
 84.4 
 81.2 
 83.5 
 78.6 
 80.7 
 75.4 
 68.9 
 72.2 
 84.6 
 79.7 
 84.2 
 86.2 
 
 s. 
 w. 
 
 s. 
 s. 
 s. 
 s. 
 s. 
 w. 
 s. 
 s. 
 s. 
 s. 
 
 3 
 1 
 4 
 1 
 3 
 5 
 4 
 6 
 10 
 5 
 3 
 6 
 
 18 
 19 
 21 
 22 
 25 
 24 
 27 
 25 
 15 
 21 
 18 
 17 
 
 10 
 8 
 6 
 7 
 3 
 1 
 
 
 5 
 5 
 9 
 8 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July . 
 
 August. . . 
 Sept 
 Oct. . 
 
 Nov. . 
 
 Dec 
 Totals . . . 
 
 
 
 
 24 72 
 
 
 
 51 
 
 4.2 
 
 252 
 21 
 
 62 
 5.1 
 
 Average . 
 
 81 
 
 19.7 
 
 51.1 
 
 2.06 
 
 79.9 
 
 s. 
 
 * Record incomplete. 
 
74 
 
 BULLETIN No. 86. 
 
 [June, 
 
 METEOROLOGICAL SUMMARY FOR THE EXPERIMENT STATION Continued 
 
 1895. 
 
 TEMPERATURES. 
 
 Rainfall 
 in 
 inches. 
 
 Rela- 
 tive 
 humid- 
 ity. 
 
 Prevailing 
 wind, 
 directions. 
 
 No. of 
 clear 
 days. 
 
 No. of 
 partly 
 cloudy 
 days. 
 
 No. of 
 cloudy 
 days. 
 
 Max. 
 
 Min. 
 
 Mean. 
 
 Jan 
 Feb 
 March . . . 
 April .... 
 May 
 
 57 
 53 
 84 
 88 
 95 
 98.5 
 94 
 97 
 87.5 
 82 
 62 
 66 
 
 -2 
 7.5 
 7 
 27 
 28 
 42 
 43 
 48 
 32 
 25 
 4 
 15 
 
 29.28 
 23.36 
 35.9 
 52.3 
 59.4 
 73.3 
 71.3 
 73.2 
 61.32 
 47.26 
 36.82 
 42.71 
 
 1.36 
 .52 
 .70 
 2.42 
 2.20 
 2.24 
 3.61 
 1.81 
 5.27 
 .21 
 3.07 
 5.71 
 
 93.3 
 91.7 
 83.3 
 78.0 
 71.2 
 67.0. 
 75.8 
 72.2 
 75.0 
 65.2 
 81.1 
 87.5 
 
 n. W. 
 n. w. 
 n. w. 
 n. e. 
 
 s. 
 s. 
 s. 
 s. 
 s. 
 n. w. 
 s. 
 s. 
 
 9 
 8 
 7 
 7 
 14 
 10 
 5 
 6 
 12 
 14 
 3 
 2 
 
 14 
 17 
 17 
 17 
 16 
 18 
 22 
 21 
 15 
 15 
 14 
 13 
 
 8 
 3 
 7 
 6 
 1 
 2 
 4 
 4 
 3 
 2 
 13 
 16 
 
 June .... 
 July 
 
 August. . . 
 Sept. . 
 
 Oct 
 
 Nov 
 Dec 
 
 Totals . . . 
 
 
 
 
 29.12 
 
 
 
 97 
 
 8 
 
 199 
 16 
 
 69 
 
 5.7 
 
 Average . 
 
 80.3 
 
 18.7 
 
 55.1 
 
 2.42 
 
 78.4 
 
 s. 
 
 1896. 
 Jan. . 
 
 52 
 68 
 67 
 86 
 91 
 92 
 95 
 97 
 91 
 79 
 74 
 62 
 
 -5 
 -4 
 6 
 21 
 45 
 49 
 49 
 44 
 30 
 24 
 9 
 8 
 
 28.1 
 29.6 
 34.4 
 57.6 
 68.2 
 70.2 
 73.8 
 72 
 61.9 
 48.8 
 39.9 
 33.3 
 
 1.12 
 1.95 
 1.22 
 1.89 
 5.62 
 2.98 
 7.87 
 3.74 
 5.84 
 .42 
 2.87 
 .39 
 
 89.6 
 81.8 
 83.0 
 70.6 
 76.2 
 78.4 
 76.3 
 80.0 
 81.4 
 78.6 
 87.9 
 87.0 
 
 s. 
 s. w. & n. w. 
 
 n. w. 
 
 s. w. 
 s. 
 s. 
 s. 
 s. 
 s. 
 n. 
 s. 
 s. w. 
 
 2 
 3 
 5 
 10 
 7 
 1 
 5 
 12 
 5 
 18 
 6 
 3 
 
 13 
 14 
 19 
 19 
 19 
 24 
 19 
 17 
 14 
 9 
 13 
 20 
 
 16 
 12 
 7 
 1 
 5 
 5 
 7 
 2 
 11 
 4 
 11 
 8 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct. . 
 
 Nov 
 Dec 
 
 Total . 
 
 
 
 
 35 91 
 
 
 
 77 
 6.4 
 
 200 
 16 
 
 89 
 7.4 
 
 Average . 
 
 79 
 
 23 
 
 51.4 
 
 2.92 
 
 80.9 
 
 s. 
 
 1897. 
 Jan. . 
 
 59 
 59 
 66 
 79 
 83 
 93 
 98 
 97 
 97.5 
 92 
 69 
 59 
 
 -15 
 -2 
 20 
 21 
 31 
 44 
 53 
 42 
 32 
 32 
 11 
 1 
 
 22 
 30 
 40 
 48 
 58 
 69.5 
 75.8 
 70.0 
 69.4 
 59.1 
 39.5 
 26.3 
 
 4.53 
 1.17 
 4.10 
 3.69 
 1.8-1 
 5.16 
 4.68 
 0.63 
 0.31 
 0.42 
 4.91 
 2.67 
 
 95 
 90 
 88 
 82 
 77 
 79 
 80 
 79.2 
 68.5 
 71.0 
 86.8 
 93.7 
 
 n. w. 
 n. w. & n. 
 
 s. e. 
 s. w. 
 n. w. 
 s. e. 
 w. & n. w. 
 n. w. 
 s. w. 
 s. & s. e. 
 n. w. 
 n. w. 
 
 10 
 3 
 3 
 3 
 6 
 1 
 10 
 13 
 24 
 20 
 9 
 2 
 
 10 
 16 
 17 
 14 
 21 
 7 
 12 
 16 
 5 
 8 
 10 
 16 
 
 11 
 9 
 11 
 13 
 4 
 22 
 9 
 2 
 1 
 3 
 11 
 13 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July . . 
 
 August . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Total . 
 
 
 
 
 34 08 
 
 
 
 104 
 
 8.7 
 
 152 
 12.5 
 
 109 
 9.1 
 
 Average . 
 
 79.3 
 
 22.5 
 
 50.6 
 
 2.84 
 
 82.5 
 
 n. w. 
 
1903.] 
 
 CLIMATE OF ILLINOIS. 
 
 75 
 
 METEOROLOGICAL SUMMARY FOR THE EXPERIMENT STATION Continued. 
 
 1898. 
 
 TEMPERATURES. 
 
 Rainfall 
 in 
 inches. 
 
 Rela- 
 tive 
 humid- 
 ity. 
 
 Prevailing 
 _wind, 
 directions. 
 
 No. of 
 
 clear 
 days. 
 
 No. of 
 partly 
 cloudy 
 days. 
 
 No. of 
 cloudy 
 days. 
 
 Max. 
 
 Min. 
 
 Mean. 
 
 Jan. . 
 
 62, 
 65 
 69 
 
 79 
 82 
 90 
 96 
 94 
 94 
 86 
 68 
 55 
 
 5 
 -6 
 15 
 22 
 38 
 49 
 47 
 53 
 45 
 40 
 *. 
 
 *! '. 
 
 30.8 
 30.3 
 39.4 
 48.5 
 61.5 
 73.6 
 76.9 
 74.0 
 68.2 
 51.4 
 36.1 
 26.8 
 
 4.77 
 1.43 
 7.76 
 2.71 
 5.65 
 6.08 
 1.89 
 3.61 
 5.13 
 4.53 
 3.01 
 1.86 
 
 87.7 
 94.2 
 90.2 
 77.3 
 83.3 
 80.5 
 78.0 
 84.0 
 85.3 
 86.9 
 88.8 
 96.0 
 
 W. 
 
 n. w. 
 n. w. 
 n. w. 
 
 s. w. 
 s. w. 
 s. w. 
 s. w. 
 s. w. 
 s. 
 s. w. 
 n. w. 
 
 6 
 3 
 6 
 3 
 4 
 8 
 13 
 9 
 4 
 4 
 11 
 10 
 
 11 
 7 
 17 
 20 
 16 
 17 
 6 
 18 
 21 
 17 
 11 
 16 
 
 14 
 18 
 8 
 7 
 10 
 5 
 12 
 4 
 6 
 10 
 8 
 5 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July . 
 
 August. . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Total . . . 
 
 
 
 
 48 43 
 
 
 
 81 
 6.7 
 
 177 
 14.7 
 
 107 
 8.9 
 
 Average . 
 
 78.3 
 
 
 51.5 
 
 4.03 
 
 86.0 
 
 s. w. 
 
 
 1899. 
 Jan 
 
 53 
 58 
 65 
 90 
 86 
 93 
 94 
 96 
 99 
 87 
 69 
 60 
 
 -12 
 -25 
 -2 
 15 
 42 
 50 
 51 
 49 
 24 
 29 
 17 
 -6 
 
 25.5 
 18.4 
 32.4 
 53.1 
 63.8 
 71.4 
 74.4 
 75.3 
 63.1 
 57.2 
 43.8 
 27.8 
 
 1.97 
 2.33 
 1.78 
 0.50 
 6.09 
 2.29 
 2.65 
 2.29 
 1.07 
 5.10 
 "1.39 
 2.14 
 
 96.4 
 96.4 
 94.1 
 89.3 
 
 82.5 
 78.3 
 79.3 
 77.2 
 74.6 
 78.0 
 88.5 
 87.6 
 
 s. w. 
 s. w. 
 n. w. 
 s. w. & s. 
 s. w. 
 s. & s. w. 
 s. w. 
 s. w. 
 s. w. 
 s. w. 
 n. e. & s. w. 
 n. w. 
 
 5 
 6 
 5 
 5 
 3 
 3 
 7 
 15 
 11 
 6 
 
 
 
 19 
 16 
 10 
 20 
 19 
 25 
 19 
 11 
 14 
 17 
 19 
 17 
 
 7 
 6 
 16 
 5 
 9 
 2 
 5 
 5 
 5 
 8 
 11 
 14 
 
 Feb 
 March . . . 
 April 
 May. . 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Total . . . 
 
 
 
 
 29.60 
 
 
 
 66 
 5.5 
 
 206 
 17.2 
 
 93 
 
 7.8 
 
 Average . 
 
 79.2 
 
 19.3 
 
 50.5 
 
 2.47 
 
 85.2 
 
 s. w. 
 
 1900. 
 Jan 
 
 61 
 63 
 61 
 
 83 
 89 
 90 
 93 
 95 
 93 
 88 
 72 
 58 
 
 -5 
 
 -6 
 
 24 
 33 
 47 
 51 
 63 
 34 
 32 
 12 
 1 
 
 30.1 
 24.0 
 32.6 
 51.2 
 63.3 
 69.3 
 74.2 
 78.4 
 68.2 
 59.9 
 39.6 
 29.9 
 
 0.17 
 3.59 
 1.79 
 0.84 
 4.60 
 4.11 
 3.81 
 6.23 
 2.23 
 2.29 
 3.42 
 1.00 
 
 92.9 
 91.2 
 90.7 
 74.9 
 74.6 
 82.1 
 79.4 
 80.0 
 78.7 
 77.6 
 65.7 
 73.9 
 
 w. 
 
 n. w. 
 n. w. 
 n. e. 
 
 s. w. 
 n. e. 
 s. w. 
 s. 
 s. e. & s. w. 
 s. e. 
 s. w. 
 s. w. 
 
 1 
 
 
 3 
 1 
 
 2 
 4 
 1 
 1 
 
 2 
 
 20 
 16 
 17 
 16 
 24' 
 21 
 5 
 26 
 24 
 25 
 22 
 21 
 
 10 
 12 
 14 
 11 
 6 
 9 
 24 
 1 
 5 
 5 
 8 
 8 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July . . 
 
 August. . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Total 
 
 
 
 
 34.08 
 
 
 
 15 
 
 1.2 
 
 237 
 19.7 
 
 113 
 
 9.4 
 
 Average . 
 
 78.8 
 
 23.9 
 
 51.7 
 
 2.84 
 
 80.1 
 
 s. w. 
 
 * Record incomplete. 
 
76 
 
 BULLETIN No. 86. 
 
 [June, 1903.] 
 
 METEOROLOGICAL SUMMARY FOR THE EXPERIMENT STATION Continued. 
 
 1901. 
 
 TEMPERATURES. 
 
 Rainfall 
 in 
 inches. 
 
 Rela- 
 tive 
 humid- 
 ity. 
 
 Prevailing 
 wind, 
 directions. 
 
 No. of 
 clear 
 days. 
 
 No. of 
 partly 
 cloudy 
 days. 
 
 No. of 
 cloudy 
 days. 
 
 Max. 
 
 Min. 
 
 Mean. 
 
 Jan. . 
 
 61 
 47 
 70 
 87 , 
 89 
 95 
 104 
 101 
 94 
 88 
 69 
 60 
 
 -7 
 -2 
 5 
 28 
 38 
 44 
 48 
 54 
 33 
 29 
 16 
 -15 
 
 27.8 
 21.0 
 37.6 
 48.5 
 59.2 
 72.2 
 79.5 
 73.8 
 64.6 
 53.5 
 35.8 
 24.2 
 
 1.55 
 1.41 
 3.14 
 0.80 
 1.93 
 5.80 
 2.48 
 1.68 
 1.38 
 4.10 
 1.31 
 3.06 
 
 92.6 
 92.1 
 85.2 
 72.7 
 82.1 
 77.9 
 77.4 
 69.7 
 75.6 
 76.4 
 80.5 
 88.8 
 
 n. w. 
 n. w. 
 s. w. 
 s. e. 
 n. e. 
 s. w. 
 s. w. 
 n. e. 
 s. w. 
 s. w. 
 n. w. 
 n. w. 
 
 
 1 
 
 4 
 2 
 2 
 2 
 2 
 4 
 6 
 
 
 
 16 
 21 
 12 
 13 
 21 
 25 
 29 
 26 
 22 
 19 
 25 
 16 
 
 15 
 6 
 19 
 13 
 8 
 3 
 
 3 
 4 
 6 
 5 
 15 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct. . . 
 
 Nov 
 Dec 
 
 Total 
 
 
 
 
 28 64 
 
 
 
 23 
 1.9 
 
 245 
 20.4 
 
 97 
 8.1 
 
 Average . 
 
 80.4 
 
 22.7 
 
 49.8 
 
 2.39 
 
 80.9 
 
 s. w. 
 
 1902. 
 Jan. . 
 
 56 
 48 
 70 
 85 
 90 
 92 
 91 
 90 
 84 
 78 
 75 
 51 
 
 -7 
 -14 
 9 
 23 
 40 
 45 
 50 
 52 
 34 
 31 
 14 
 
 
 25.7 
 16.8 
 40.8 
 48.1 
 65.8 
 68.4 
 74.6 
 69.4 
 61.7 
 54.5 
 46.6 
 27.0 
 
 0.62 
 1.48 
 1.69 
 2.11 
 2.60 
 *11.73 
 4.02 
 9.80 
 4.90 
 2.10 
 2.42 
 2.94 
 
 83.5 
 86.3 
 81.4 
 73.9 
 75.0 
 78.1 
 77.1 
 80.1 
 82.5 
 80.8 
 83.0 
 89.3 
 
 n. w. 
 n. w. 
 s. w. 
 s. w. & n. w. 
 
 s. e. & s. w. 
 s. w. 
 s. w. 
 s. 
 s. 
 s. w. 
 s. w. 
 s. w. 
 
 
 1 
 
 
 2 
 1 
 13 
 6 
 3 
 1 
 
 1 
 
 25 
 21 
 18 
 26 
 25 
 21 
 14 
 19 
 15 
 24 
 18 
 15 
 
 6 
 6 
 13 
 4 
 4 
 8 
 4 
 6 
 12 
 6 
 12 
 15 
 
 Feb 
 March . . . 
 April .... 
 May 
 
 June .... 
 July 
 
 August. . . 
 Sept 
 Oct 
 
 Nov 
 Dec 
 
 Total 
 
 
 
 
 46.41 
 
 
 
 28 
 2.3 
 
 241 
 20.1 
 
 96 
 
 8 
 
 Average . 
 
 75.9 
 
 23.1 
 
 49.9 
 
 3.87 
 
 80.9 
 
 s. w. 
 
 * The storm during the night of June 10 blew the rain-gauge over, but .75 inch 
 is included, which was about the rainfall during the storm. 
 
 - 
 
UNIVERSITY OF ILLINOIS-URBANA