Historical Climate Data

Precipitation Summary

Station: 111577 CHICAGO MIDWAY AP 3SW, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 1.95 1.78 2.83 3.82 3.86 4.16 3.82 3.91 3.45 2.79 3.22 2.76 38.35

Precipitation Extremes

Period of Record: 1928-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 5.32 2005 0.13 1981 2.76 01-12-1960
Feb 6.76 1997 0.25 1969 3.25 02-21-1997
Mar 5.37 1976 0.33 1958 2.50 03-31-1929
Apr 8.33 1947 0.45 1971 3.83 04-18-1975
May 7.59 1945 0.25 1992 3.30 05-11-1966
Jun 13.03 1993 0.78 1956 4.64 06-13-1976
Jul 10.29 1996 0.31 1936 6.16 07-12-1957
Aug 9.95 1987 0.76 1996 3.90 08-26-1987
Sep 14.17 1961 0.01 1979 4.16 09-11-2000
Oct 12.06 1954 0.20 1964 3.95 10-03-1954
Nov 7.63 1985 0.55 1976 3.49 11-10-1995
Dec 7.21 1982 0.30 1962 2.78 12-02-1982
             
Annual 49.64 1993 21.32 1943 6.16 07-12-1957
Winter 13.79 1950 1.45 1931 3.25 02-21-1997
Spring 17.02 1983 2.79 1934 3.83 04-18-1975
Summer 21.69 1993 4.58 2005 6.16 07-12-1957
Fall 19.32 1961 2.07 1956 4.16 09-11-2000

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 11.2 5.0 0.9 0.3
Feb 8.9 4.6 0.9 0.1
Mar 11.7 6.6 1.8 0.4
Apr 11.6 7.2 2.4 0.9
May 11.0 7.1 2.5 0.8
Jun 10.3 6.4 2.9 1.2
Jul 9.5 6.1 2.4 1.0
Aug 9.6 6.3 2.7 1.2
Sep 8.9 5.5 2.1 0.8
Oct 9.7 5.6 1.8 0.6
Nov 11.5 6.7 2.0 0.6
Dec 11.3 5.3 1.7 0.5
         
Annual 125.1 72.5 24.1 8.4
Winter 31.4 15.0 3.5 0.9
Spring 34.2 21.0 6.7 2.1
Summer 29.4 18.9 8.0 3.3
Fall 30.1 17.7 5.9 2.0

Temperature Summary

Station 111577 CHICAGO MIDWAY AP 3SW, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 30.7 36.1 47.4 59.2 71.3 80.8 84.7 82.3 75.1 63.2 48.0 35.6 59.5
Low °F 16.2 21.3 30.6 40.2 50.9 60.7 66.3 65.0 56.7 44.9 33.6 22.2 42.4
Mean °F 23.5 28.7 39.0 49.7 61.1 70.8 75.5 73.7 65.9 54.1 40.8 28.9 51.0
HDD 1288 1017 805 462 203 28 4 11 67 352 726 1120 6083
CDD 0 0 0 4 82 199 330 279 95 12 0 0 1001

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

Temperature Extremes

Period of Record: 1928-2006


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 36.5 2006 10.1 1977 67 01-25-1950 -25 01-20-1985
Feb 39.7 1998 13.6 1936 75 02-27-1976 -20 02-09-1933
Mar 48.6 1945 26.4 1960 86 03-29-1986 -7 03-08-1943
Apr 57.0 1955 41.7 1950 92 04-30-1942 10 04-07-1982
May 69.3 1977 53.0 1935 102 05-31-1934 28 05-12-1981
Jun 76.4 1933 63.0 1928 107 06-01-1934 35 06-04-1945
Jul 81.3 1999 70.6 1967 107 07-11-1936 46 07-05-1972
Aug 81.3 1995 69.2 1967 103 08-22-1936 43 08-29-1965
Sep 71.7 2005 60.4 1949 102 09-15-1939 29 09-28-1942
Oct 64.3 1963 48.2 1987 94 10-06-1963 20 10-20-1930
Nov 50.3 2001 32.8 1976 81 11-01-1950 -3 11-28-1930
Dec 37.1 1982 16.5 1983 71 12-03-1970 -20 12-24-1983
                 
Annual 55.0 1998 40.0 1929 107 06-01-1934 -25 01-20-1985
Winter 34.2 2002 18.5 1979 75 02-27-1976 -25 01-20-1985
Spring 56.2 1977 44.1 1947 102 05-31-1934 -7 03-08-1943
Summer 78.2 1995 69.8 1945 107 06-01-1934 35 06-04-1945
Fall 59.2 1963 48.6 1976 102 09-15-1939 -3 11-28-1930

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 16.3 28.1 4.6
Feb 0.0 10.7 22.9 1.8
Mar 0.0 3.4 18.4 0.0
Apr 0.1 0.1 5.3 0.0
May 1.3 0.0 0.4 0.0
Jun 4.6 0.0 0.0 0.0
Jul 8.4 0.0 0.0 0.0
Aug 5.0 0.0 0.0 0.0
Sep 1.9 0.0 0.0 0.0
Oct 0.1 0.0 2.0 0.0
Nov 0.0 1.9 13.7 0.0
Dec 0.0 10.0 25.3 1.8
         
Annual 21.4 42.6 116.1 8.3
Winter 0.0 37.1 76.2 8.2
Spring 1.4 3.5 24.2 0.0
Summer 17.9 0.0 0.0 0.0
Fall 2.0 1.8 15.4 0.0

Snowfall Summary

Station: 111577 CHICAGO MIDWAY AP 3SW, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 12.9 10.3 6.0 1.4 0.0 0.0 0.0 0.0 0.0 0.1 2.3 10.1 43.1

Snowfall Extremes

Period of Record: 1928-2006

Month High (in) Year 1-Day Max (in) Date
Jan 40.4 1979 17.6 01-02-1999
Feb 26.2 1994 11.0 02-07-1933
Mar 24.1 1930 16.5 03-25-1930
Apr 12.2 1982 9.8 04-05-1982
May 3.7 1940 3.2 05-01-1940
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 4.4 1967 3.0 10-20-1952
Nov 13.0 1951 8.0 11-06-1951
Dec 41.3 2000 14.5 12-11-2000
Season (Jul-Jun) 93.3 1978-1979 17.6 01-02-1999

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 6.2 3.0 1.9 0.4
Feb 6.2 3.0 1.9 0.4
Mar 4.5 1.9 1.0 0.2
Apr 1.0 0.3 0.1 0.1
May 0.1 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 0.2 0.0 0.0 0.0
Nov 2.7 0.8 0.4 0.0
Dec 7.2 2.8 1.4 0.4
Annual 30.5 12.9 6.9 1.5

Growing Season Summary

Station: 111577 CHICAGO MIDWAY AP 3SW, 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 7 23 115 317 656 927 1104 1053 789 449 137 25 5587
45 2 8 65 200 503 777 950 898 639 307 72 11 4423
50 0 2 34 112 357 627 795 743 491 188 35 4 3385
55 0 0 15 57 230 478 641 588 346 102 14 1 2473
60 0 0 6 26 133 334 487 434 219 46 4 0 1691
50** 3 12 66 174 390 611 760 722 496 244 64 11 3549

**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 4/17 3/26 4/06 5/10 5/16 10/23 10/01 10/07 11/12 11/19
30 4/10 3/23 3/27 4/23 5/12 11/02 10/02 10/17 11/13 11/19
28 4/08 3/18 3/22 4/17 5/12 11/04 10/02 10/21 11/20 11/27
24 3/24 3/08 3/13 4/10 4/19 11/13 10/24 11/03 12/03 12/21
20 3/16 2/12 2/24 4/06 4/09 11/22 10/24 11/07 12/11 12/21
16 3/03 1/27 2/09 4/01 4/07 12/03 11/02 11/16 12/20 12/24

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 187 143 157 215 226
30 205 160 179 221 228
28 212 164 193 239 251
24 234 207 213 257 281
20 250 222 229 283 285
16 275 222 240 297 324

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