ILLINOIS CLIMATE

Probability of last spring freeze (32° or lower) after date shown by districts
Probability NW NE* W C E WSW ESE SW SE
3 years in 4 Apr. 21 Apr. 19 Apr. 13 Apr. 16 Apr. 16 Apr. 10 Apr. 11 Apr. 2 Apr. 3
1 year in 2 Apr. 30 Apr. 28 Apr. 22 Apr. 25 Apr. 25 Apr. 19 Apr. 20 Apr. 11 Apr. 12
1 year in 4 May 9 May 7 May 1 May 4 May 4 Apr. 28 Apr. 29 Apr. 20 Apr. 21
1 year in 10 May 17 May 15 May 9 May 12 May 12 May 6 May 7 Apr. 28 Apr. 29
1 year in 20 May 22 May 20 May 14 May 17 May 17 May 11 May 12 May 3 May 4
* Last spring freeze averages approximately ten days earlier in Cook County near Lake Michigan.
Source: Illinois State Water Survey.

Probability of first fall freeze (32° or lower) before date shown by districts
Probability NW NE* W C E WSW ESE SW SE
3 years in 4 Oct. 17 Oct. 18 Oct. 25 Oct. 26 Oct. 25 Oct. 28 Oct. 28 Nov. 3 Nov. 4
1 year in 2 Oct. 8 Oct. 9 Oct. 16 Oct. 17 Oct. 16 Oct. 19 Oct. 19 Oct. 25 Oct. 26
1 year in 4 Sep. 29 Sep. 30 Oct. 7 Oct. 8 Oct. 7 Oct. 10 Oct. 10 Oct. 16 Oct. 17
1 year in 10 Sep. 22 Sep. 23 Sep. 30 Oct. 1 Sep. 30 Oct. 3 Oct. 3 Oct. 9 Oct. 10
1 year in 20 Sep. 17 Sep. 18 Sep. 25 Sep. 26 Sep. 25 Sep. 28 Sep. 28 Oct. 4 Oct. 5
*First fall freeze averages approximately ten days later in Cook County near Lake Michigan. Source: Illinois State Water Survey

MONTHLY PRECIPITATION: Avg. number of inches and departures from long term means by districts, 1996


Month		 NW NE W C E WSW ESE SW SE
Prec. Dep. Prec. Dep. Prec. Dep. Prec. Dep. Prec. Dep. Prec. Dep. Prec. Dep. Prec. Dep. Prec. Dep.
Jan. 1.65 0.32 1.40 -0.17 2.36 0.91 1.58 0.01 1.67 0.02 2.02 0.35 4.03 2.00 3.56 1.20 3.56 0.87
Feb. 0.73 -0.41 0.78 -0.55 0.83 -0.58 0.82 -0.69 0.84 -0.79 1.08 -0.79 0.75 -1.46 0.72 -2.07 0.87 -2.18
March 0.77 -1.83 0.93 -1.75 1.63 -1.46 1.76 -1.32 1.75 -1.24 2.52 -0.86 2.70 -1.04 3.32 -1.01 4.02 -0.73
April 2.57 -1.11 2.89 -0.84 2.46 -1.30 2.89 -0.86 3.07 -0.71 5.90 2.20 7.33 3.50 9.26 5.33 9.59 5.20
May 9.09 5.21 7.20 3.56 10.11 6.01 7.50 3.52 7.46 3.46 7.73 3.45 7.94 3.71 5.73 1.29 5.65 0.76
June 4.51 0.33 4.99 0.94 3.02 -0.96 2.83 -0.99 5.09 1.24 3.08 -0.64 4.18 0.37 4.52 0.78 5.70 1.84
July 4.65 0.66 8.17 4.19 3.89 -0.50 4.71 0.76 5.86 1.65 3.20 -0.71 2.23 -2.00 3.36 -0.49 4.74 0.69
August 3.36 -0.72 2.00 -1.96 2.55 -1.19 1.41 -2.04 1.66 -1.97 2.17 -1.20 1.58 -1.78 1.32 -2.19 1.58 -1.79
Sept. 1.95 -1.92 2.37 -1.42 2.29 -1.99 2.05 -1.70 2.47 -0.94 2.27 1.23 3.96 0.81 4.87 1.59 4.96 1.88
Oct. 3.39 0.64 2.50 0.00 1.60 -1.41 2.23 -0.49 2.18 -0.46 2.19 -0.63 2.24 -0.62 2.77 -0.19 3.00 -0.01
Nov. 1.14 -1.35 1.56 -1.27 1.53 -1.10 2.75 -0.02 2.94 0.03 3.93 0.87 4.66 1.16 5.09 1.25 5.53 1.52
Dec. 1.36 -0.68 1.65 -0.73 0.56 -1.72 1.26 -1.42 1.43 -1.35 0.87 -2.08 2.17 -1.25 2.99 -0.78 4.06 0.01
Annual 35.17 -0.86 36.44 0.00 32.83 -5.29 31.79 -5.24 36.42 -1.06 36.96 -1.27 43.77 3.40 47.51 4.71 53.26 8.06
Source: National Weather Service

MONTHLY TEMPERATURES: Average temperature and departures from long term means by district, 1996


Month		 NW NE W C E WSW ESE SW SE
Temp. Dep. Temp. Dep. Temp. Dep. Temp. Dep. Temp. Dep. Temp. Dep. Temp. Dep. Temp. Dep. Temp. Dep.
Jan. 19.2 0.0 21.7 1.0 22.3 -0.9 23.0 0.0 22.9 -0.1 24.9 -1.0 25.9 -0.8 30.6 0.3 30.9 0.3
Feb. 23.6 -0.4 25.0 -0.2 28.0 0.0 29.4 1.8 28.7 1.4 31.5 1.1 32.8 1.6 36.6 1.9 36.2 1.2
March 30.1 -6.3 30.2 -6.5 32.9 -7.1 33.6 -6.2 32.9 -6.5 35.3 -6.8 36.5 -6.3 39.4 -6.3 38.8 -7.2
April 45.6 -3.8 44.8 -3.9 48.1 -4.5 48.3 -3.9 47.2 -4.1 49.5 -4.7 50.5 -3.8 52.7 -4.0 52.3 -4.4
May 56.1 -4.5 55.1 -4.5 60.4 -2.4 60.3 -2.3 59.5 -2.6 63.7 -0.2 65.2 1.1 68.0 2.3 68.0 2.3
June 69.1 -0.8 68.3 -1.0 71.4 -0.6 71.3 -0.6 70.9 -0.6 72.1 -0.7 73.3 0.3 74.1 -0.2 73.9 -0.3
July 70.1 -3.7 70.0 -3.5 72.7 -3.4 72.3 -3.0 72.0 -2.7 73.5 -3.1 74.6 -1.9 75.6 -2.5 75.1 -2.8
August 71.1 -0.3 71.8 0.2 73.2 -0.2 72.9 -0.1 72.6 0.3 74.4 0.3 75.5 1.2 76.6 0.6 76.4 0.4
Sept. 62.0 -1.8 63.0 -1.4 63.6 -2.7 64.0 -2.3 63.7 -2.3 64.6 -2.9 65.7 -2.2 66.5 -2.8 66.6 -2.9
Oct. 52.0 -0.3 52.2 -0.7 54.8 -0.1 54.4 -0.1 54.3 0.3 55.9 -0.1 56.7 0.6 57.7 -0.3 57.4 -0.5
Nov. 30.9 -8.0 31.9 -8.2 33.6 -8.2 33.8 -7.9 33.8 -7.8 35.7 -8.0 37.2 -7.0 39.8 -6.7 40.1 -6.8
Dec. 24.0 -0.8 26.5 0.0 27.6 -0.6 29.2 0.9 29.1 0.6 31.8 0.8 33.9 2.0 37.1 2.2 37.5 2.1
Annual 46.2 -2.5 46.7 -2.3 49.1 -2.5 49.4 -1.9 49.0 -1.9 51.1 -2.0 52.3 -1.2 54.6 -1.2 54.4 -1.5
Source: National Weather Service

Illinois Agricultural Statistics Service
Annual Summary - 1997		 Page 17


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