Historical Climate Data

Precipitation Summary

Station: 117636 SALEM, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 2.46 2.53 3.98 4.01 4.37 4.15 3.90 3.43 3.22 3.10 4.12 3.26 42.53

Precipitation Extremes

Period of Record: 1915-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 9.43 1949 0.13 1986 2.76 01-30-1916
Feb 6.14 1950 0.01 1947 2.54 02-13-1946
Mar 10.91 1945 0.48 1917 2.75 03-09-1964
Apr 11.05 1994 1.02 1976 3.42 04-21-1984
May 15.07 1995 0.99 2005 4.55 05-08-1961
Jun 10.66 1970 0.22 1933 4.40 06-15-1957
Jul 10.63 1942 0.23 1930 4.42 07-09-1942
Aug 10.23 1920 0.24 1955 4.90 08-04-1998
Sep 9.81 1984 0.30 1963 3.19 09-01-1959
Oct 14.08 1919 0.15 1944 4.26 10-26-1919
Nov 11.90 1985 0.26 1976 4.85 11-14-1993
Dec 10.57 1967 0.42 1955 4.27 12-21-1967
             
Annual 61.14 1957 27.54 1947 4.90 08-04-1998
Winter 18.70 1950 2.99 1931 4.27 12-21-1967
Spring 22.68 1945 5.11 1936 4.55 05-08-1961
Summer 23.47 1942 4.03 1933 4.90 08-04-1998
Fall 20.80 1984 3.04 1999 4.85 11-14-1993

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 9.3 5.1 1.6 0.5
Feb 7.9 4.9 1.8 0.5
Mar 10.5 7.4 2.9 1.1
Apr 10.8 7.6 2.7 0.9
May 11.3 7.9 2.9 1.0
Jun 9.7 7.0 2.8 1.1
Jul 8.3 5.6 2.8 1.2
Aug 8.4 5.9 2.3 0.8
Sep 7.3 5.0 2.2 1.0
Oct 8.7 5.3 2.3 0.8
Nov 9.9 6.8 3.0 1.1
Dec 9.5 6.2 2.2 0.7
         
Annual 111.6 74.8 29.5 10.6
Winter 26.7 16.2 5.6 1.6
Spring 32.6 22.8 8.5 3.0
Summer 26.4 18.6 7.9 3.1
Fall 25.9 17.2 7.5 2.9

Temperature Summary

Station 117636 SALEM, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 36.8 42.7 54.1 65.4 75.3 84.2 88.2 86.6 79.6 68.6 53.7 41.6 64.7
Low °F 18.1 22.3 32.5 43.6 53.7 63.2 68.1 66.0 57.2 45.1 33.9 23.9 44.0
Mean °F 27.5 32.5 43.3 54.5 64.5 73.7 78.2 76.3 68.4 56.9 43.8 32.8 54.4
HDD 1166 910 674 326 122 7 0 3 46 279 636 1000 5169
CDD 0 0 0 11 108 269 408 353 146 25 0 0 1320

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

Temperature Extremes

Period of Record: 1958-2006


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 40.9 1990 14.4 1977 70 01-23-1967 -23 01-19-1994
Feb 43.9 1976 21.5 1978 78 02-13-1962 -23 02-10-1982
Mar 51.3 1973 29.0 1960 85 03-30-1986 -8 03-05-1978
Apr 62.6 1981 49.7 1983 91 04-29-1987 20 04-07-1990
May 73.1 1962 60.5 1961 94 05-20-1987 31 05-01-1960
Jun 78.2 1984 68.9 2003 101 06-24-1988 38 06-03-1969
Jul 82.0 1980 73.7 1971 104 07-15-1980 48 07-27-1962
Aug 82.7 1983 70.4 1967 105 08-20-1983 44 08-13-1964
Sep 73.6 1960 63.3 1974 100 09-06-1960 33 09-23-1974
Oct 65.8 1963 51.0 1987 93 10-11-1963 21 10-24-1981
Nov 51.7 1990 36.8 1976 82 11-02-1987 2 11-17-1959
Dec 41.9 1982 20.4 2000 74 12-02-1982 -20 12-22-1989
                 
Annual 60.6 1958 53.3 1979 105 08-20-1983 -23 01-19-1994
Winter 37.7 1992 24.6 1978 78 02-13-1962 -23 01-19-1994
Spring 60.8 1991 49.5 1960 94 05-20-1987 -8 03-05-1978
Summer 79.2 1983 72.5 2004 105 08-20-1983 38 06-03-1969
Fall 61.5 1973 51.6 1976 100 09-06-1960 2 11-17-1959

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 10.1 26.6 2.2
Feb 0.0 5.6 20.3 1.2
Mar 0.0 0.9 13.9 0.1
Apr 0.1 0.0 3.9 0.0
May 1.3 0.0 0.1 0.0
Jun 8.1 0.0 0.0 0.0
Jul 14.8 0.0 0.0 0.0
Aug 10.8 0.0 0.0 0.0
Sep 3.7 0.0 0.0 0.0
Oct 0.0 0.0 2.9 0.0
Nov 0.0 0.4 12.4 0.0
Dec 0.0 5.4 22.7 1.1
         
Annual 38.7 22.4 102.9 4.6
Winter 0.0 21.1 69.6 4.5
Spring 1.3 0.9 17.9 0.1
Summer 33.6 0.0 0.0 0.0
Fall 3.8 0.4 15.4 0.0

Snowfall Summary

Station: 117636 SALEM, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 5.3 3.3 1.5 0.3 0.0 0.0 0.0 0.0 0.0 0.1 0.6 3.3 14.4

Snowfall Extremes

Period of Record: 1915-2006

Month High (in) Year 1-Day Max (in) Date
Jan 17.4 1977 13.5 01-31-1982
Feb 16.0 1984 10.0 02-27-1984
Mar 16.0 1960 10.5 03-12-2000
Apr 6.3 1971 6.3 04-06-1971
May 0.0 - - -
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 2.5 1993 2.5 10-31-1993
Nov 5.5 1958 5.5 11-28-1958
Dec 16.7 2000 11.0 12-06-1950
Season (Jul-Jun) 28.7 2002-2003 13.5 01-31-1982

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 2.0 1.1 0.8 0.1
Feb 2.0 1.1 0.8 0.1
Mar 0.8 0.4 0.3 0.1
Apr 0.1 0.1 0.1 0.0
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 0.0 0.0 0.0 0.0
Nov 0.4 0.2 0.2 0.0
Dec 2.1 1.3 0.6 0.2
Annual 8.8 5.1 2.9 0.6

Growing Season Summary

Station: 117636 SALEM, 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 31 72 225 475 785 1028 1184 1122 867 546 218 60 6618
45 12 34 136 338 630 878 1029 967 717 398 131 28 5304
50 4 13 74 219 476 728 874 812 567 264 70 12 4118
55 1 4 34 125 329 578 719 657 421 155 31 4 3063
60 0 1 13 62 200 429 564 502 285 76 10 0 2146
50** 18 45 138 289 500 697 811 766 569 340 124 32 4335

**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 4/12 3/24 3/29 4/24 5/05 10/20 10/02 10/06 11/05 11/10
30 4/10 3/18 3/26 4/21 4/29 10/25 10/03 10/10 11/09 11/23
28 4/06 3/07 3/16 4/14 4/20 11/03 10/03 10/14 11/22 11/28
24 3/20 2/28 3/09 4/10 4/18 11/13 10/20 10/28 12/05 12/11
20 3/10 2/09 2/21 3/25 4/07 11/25 11/02 11/08 12/14 12/22
16 2/26 1/15 2/07 3/16 3/25 12/08 11/03 11/11 12/22 12/25

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 190 167 170 212 226
30 199 174 177 226 235
28 212 177 189 242 252
24 235 199 217 256 271
20 259 228 237 287 289
16 284 237 260 305 340

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