Historical Climate Data

Precipitation Summary

Station: 118916 WALNUT, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 1.31 1.35 2.65 3.49 4.43 4.52 3.61 4.36 3.45 2.80 2.57 2.03 36.57

Precipitation Extremes

Period of Record: 1893-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 5.25 1916 0.06 1961 2.51 01-24-1938
Feb 3.91 1909 0.10 1969 2.43 02-21-1997
Mar 6.08 1973 0.27 1958 2.34 03-25-1954
Apr 8.12 1967 0.51 1901 2.55 04-01-1983
May 11.14 1974 0.64 1992 5.31 05-10-1951
Jun 10.99 1998 0.32 1988 6.38 06-24-1994
Jul 11.01 1902 0.26 1894 3.66 07-21-1948
Aug 13.54 1987 0.48 1893 4.57 08-20-1979
Sep 12.83 1926 0.00 1979 4.08 09-01-1926
Oct 10.93 1941 0.00 1964 5.20 10-03-1941
Nov 7.65 1985 0.06 1904 2.76 11-17-1928
Dec 5.73 1971 0.00 1939 3.30 12-10-2003
             
Annual 51.99 1998 16.24 2005 6.38 06-24-1994
Winter 8.57 1974 1.09 1961 3.30 12-10-2003
Spring 18.14 1973 2.72 1934 5.31 05-10-1951
Summer 24.53 1902 4.25 1988 6.38 06-24-1994
Fall 20.56 1941 2.73 1956 5.20 10-03-1941

Precipitation Threshold Climatology

Derived from 1971-2000 Averages:

*Annual/seasonal totals may differ from the sum of the monthly totals due to rounding.


Month 		# Days
Total ≥ 0.01" 		# Days
Total ≥ 0.10" 		# Days
Total ≥ 0.50" 		# Days
Total ≥ 1.00"
Jan 6.4 4.3 0.5 0.1
Feb 5.2 3.8 0.7 0.2
Mar 8.2 6.3 1.9 0.4
Apr 8.8 7.1 2.3 0.8
May 9.5 7.8 3.1 1.1
Jun 8.5 7.0 3.2 1.1
Jul 8.1 6.4 2.7 1.0
Aug 8.3 6.8 2.6 1.3
Sep 7.2 5.9 2.5 0.9
Oct 6.9 5.4 1.9 0.8
Nov 7.0 5.7 1.8 0.4
Dec 6.7 5.1 1.0 0.4
         
Annual 90.8 71.7 24.3 8.5
Winter 18.3 13.2 2.3 0.7
Spring 26.5 21.3 7.3 2.3
Summer 24.8 20.2 8.5 3.4
Fall 21.1 17.0 6.2 2.1

Temperature Summary

Station 118916 WALNUT, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 28.0 33.1 45.7 59.3 71.3 80.5 83.4 81.4 74.5 62.9 46.1 33.0 58.3
Low °F 10.7 16.7 28.1 38.7 50.6 59.7 63.6 61.3 52.8 40.9 29.4 17.2 39.1
Mean °F 19.4 24.9 36.9 49.0 61.0 70.1 73.5 71.4 63.7 51.9 37.8 25.1 48.7
HDD 1415 1122 870 484 202 18 6 22 105 413 818 1237 6712
CDD 0 0 0 4 76 171 270 220 63 7 0 0 811

HDD - heating degree days (base 65F); CDD - cooling degree days (base 65F)

Temperature Extremes

Period of Record: 1893-2006


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 35.4 1933 7.0 1977 73 01-26-1942 -27 01-20-1985
Feb 37.0 1930 11.6 1936 70 02-26-2000 -26 02-13-1905
Mar 50.0 1910 22.4 1960 87 03-29-1986 -13 03-01-1962
Apr 58.4 1955 43.4 1950 94 04-30-1895 6 04-06-1982
May 69.4 1977 54.3 1917 105 05-31-1934 24 05-03-2005
Jun 79.2 1934 64.8 1916 106 06-01-1934 37 06-06-1894
Jul 82.6 1936 69.1 1992 111 07-14-1936 44 07-02-1904
Aug 81.9 1947 65.4 1992 105 08-18-1936 36 08-27-1923
Sep 73.9 1897 58.7 1924 103 09-13-1897 22 09-30-1899
Oct 63.9 1963 42.8 1925 98 10-01-1897 10 10-28-1925
Nov 48.8 1931 30.7 1996 81 11-01-1950 -8 11-29-1976
Dec 37.3 1923 11.7 1983 68 12-05-1998 -23 12-28-1924
                 
Annual 54.5 1931 45.4 1989 111 07-14-1936 -27 01-20-1985
Winter 34.0 1932 15.6 1979 73 01-26-1942 -27 01-20-1985
Spring 56.4 1977 43.7 1960 105 05-31-1934 -13 03-01-1962
Summer 77.3 1934 67.4 1992 111 07-14-1936 36 08-27-1923
Fall 59.3 1931 47.2 1976 103 09-13-1997 -8 11-29-1976

Temperature Threshold Climatology

Derived from 1971-2000 Averages:

*Annual/seasonal values may differ from the sum of the monthly values due to rounding.


Month 		# Days
High ≥ 90°F 		# Days
High ≤ 32°F 		# Days
Low ≤ 32°F 		# Days
Low ≤ 0°F
Jan 0.0 18.0 30.3 8.3
Feb 0.0 12.2 25.7 4.4
Mar 0.0 3.7 22.2 0.3
Apr 0.1 0.1 8.3 0.0
May 1.0 0.0 0.5 0.0
Jun 3.9 0.0 0.0 0.0
Jul 7.3 0.0 0.0 0.0
Aug 4.1 0.0 0.0 0.0
Sep 1.4 0.0 0.6 0.0
Oct 0.1 0.0 6.7 0.0
Nov 0.0 3.1 19.1 0.2
Dec 0.0 12.5 28.7 4.2
         
Annual 17.8 50.0 142.5 17.5
Winter 0.0 42.9 84.6 16.9
Spring 1.1 3.8 31.0 0.3
Summer 15.4 0.0 0.0 0.0
Fall 1.4 3.1 26.3 0.2

Snowfall Summary

Station: 118916 WALNUT, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 10.5 6.8 3.9 1.0 0.0 0.0 0.0 0.0 0.0 0.1 1.9 8.7 32.9

Snowfall Extremes

Period of Record: 1893-2006

Month High (in) Year 1-Day Max (in) Date
Jan 31.9 1979 18.0 01-13-1979
Feb 19.0 1994 12.0 02-19-2000
Mar 22.6 1972 9.8 03-31-1926
Apr 12.6 1926 8.5 04-17-1926
May 0.0 - - -
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 6.3 1929 6.0 10-27-1967
Nov 11.0 1926 6.6 11-18-1926
Dec 29.5 2000 14.0 12-01-2006
Season (Jul-Jun) 69.4 1978-1979 18.0 01-13-1979

Snowfall Threshold Climatology

Derived from 1971-2000 Averages

*Annual values may differ from the sum of the monthly values due to rounding.


Month 		# Days
Total ≥ 0.1" 		# Days
Total ≥ 1.0" 		# Days
Total ≥ 2.0" 		# Days
Total ≥ 5.0"
Jan 2.9 2.7 1.8 0.2
Feb 2.9 2.7 1.8 0.2
Mar 1.8 1.5 0.7 0.2
Apr 0.4 0.4 0.2 0.1
May 0.0 0.0 0.0 0.0
Jun 0.0 0.0 0.0 0.0
Jul 0.0 0.0 0.0 0.0
Aug 0.0 0.0 0.0 0.0
Sep 0.0 0.0 0.0 0.0
Oct 0.1 0.1 0.0 0.0
Nov 1.1 0.9 0.5 0.0
Dec 3.7 3.4 1.9 0.5
Annual 14.6 13.1 7.2 1.5

Growing Season Summary

Station: 118916 WALNUT, IL

Growing Degree Day Averages

Derived from 1971-2000 Data

Base Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
40 3 15 96 308 668 913 1055 989 723 399 101 13 5225
45 0 4 52 195 515 764 900 835 575 267 51 5 4114
50 0 0 26 110 368 615 746 680 431 161 23 2 3120
55 0 0 10 54 238 466 591 525 294 84 9 0 2241
60 0 0 3 24 137 322 437 372 178 35 2 0 1488
50** 2 9 63 188 411 604 715 663 460 245 57 7 3387

**Modified Growing Degree Days: Base 50, Ceiling 86.

Growing Season Summary

Derived from 1971-2000 Averages

Date of Last Spring Occurrence Date of First Fall Occurrence
Temp °F Median Early 90% 10% Late Median Early 90% 10% Late
32 4/27 3/29 4/10 5/10 5/27 10/08 9/20 9/22 10/17 11/03
30 4/22 3/28 4/07 5/03 5/27 10/13 9/20 9/23 11/03 11/10
28 4/13 3/27 4/03 4/25 5/03 10/19 10/02 10/02 11/05 11/14
24 4/06 3/22 3/25 4/19 4/22 11/02 10/02 10/12 11/17 11/20
20 3/25 2/22 3/14 4/09 4/22 11/10 10/20 10/24 11/23 11/30
16 3/14 2/09 2/19 4/06 4/09 11/20 10/30 11/07 12/08 12/22

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 166 136 145 185 199
30 176 137 152 199 207
28 189 161 170 208 219
24 206 176 192 229 234
20 224 194 209 253 259
16 251 217 222 282 299

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Copyright 2007 Illinois State Water Survey
Jim Angel, State Climatologist, jimangel@illinois.edu
Last Modified: September 11, 2007