Historical Climate Data

Precipitation Summary

Station: 110993 BROOKPORT DAM 52, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 3.51 3.91 4.42 4.70 4.76 4.03 4.28 3.00 3.27 3.23 4.45 4.37 47.93

Precipitation Extremes

Period of Record: 1928-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 19.03 1937 0.22 1943 5.22 01-25-1949
Feb 13.21 1989 0.36 1947 5.32 02-14-1989
Mar 10.89 1935 0.55 1941 4.64 03-31-1938
Apr 11.75 1983 1.20 1959 5.20 04-30-1983
May 9.86 1983 1.05 1932 4.46 05-11-1943
Jun 12.68 1935 0.17 1952 4.23 06-08-1979
Jul 12.01 1958 0.39 1970 3.76 07-16-1958
Aug 9.67 1942 0.47 1936 4.57 08-23-1942
Sep 9.76 1932 0.04 1998 4.35 09-20-1932
Oct 7.59 1985 0.01 1964 3.50 10-07-1998
Nov 12.07 1957 0.75 1949 4.45 11-22-1934
Dec 10.09 1982 0.36 1958 3.50 12-17-2001
             
Annual 68.80 2006 29.11 1963 5.32 02-14-1989
Winter 27.92 1950 3.79 1943 5.32 02-14-1989
Spring 27.79 1973 5.46 1930 5.20 04-30-1983
Summer 25.00 1958 4.14 1930 4.57 08-23-1942
Fall 20.52 2006 3.73 1963 4.45 11-22-1934

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 9.5 6.1 2.4 1.0
Feb 9.0 6.2 2.5 1.1
Mar 11.6 8.0 2.7 1.2
Apr 10.7 7.3 3.3 1.3
May 10.9 7.8 3.2 1.3
Jun 9.5 6.6 2.9 1.1
Jul 8.2 5.6 2.9 1.6
Aug 7.0 5.0 2.1 0.6
Sep 7.4 5.2 2.4 1.1
Oct 7.7 5.3 2.3 0.8
Nov 9.6 6.7 3.4 1.4
Dec 10.2 7.1 3.5 1.2
         
Annual 111.4 76.8 33.4 13.7
Winter 28.7 19.3 8.3 3.3
Spring 33.2 23.1 9.2 3.8
Summer 24.7 17.2 7.8 3.3
Fall 24.6 17.1 8.0 3.3

Temperature Summary

Station 110993 BROOKPORT DAM 52, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 42.3 48.3 58.4 68.8 77.5 85.9 89.5 88.4 81.7 71.1 57.7 46.5 68.0
Low °F 25.0 29.0 37.6 46.6 55.9 64.2 68.4 66.1 58.7 46.9 38.0 28.9 47.1
Mean °F 33.7 38.7 48.0 57.7 66.7 75.1 79.0 77.3 70.2 59.0 47.9 37.7 57.6
HDD 971 737 529 238 79 2 0 1 37 227 515 847 4183
CDD 0 0 1 19 132 304 432 381 192 39 1 0 1501

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

Temperature Extremes

Period of Record: 1962-2006


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 45.0 2006 20.5 1977 73 01-23-1967 -21 01-21-1984
Feb 46.8 1976 24.1 1978 74 02-25-1981 -9 02-03-1985
Mar 55.0 1976 40.2 1965 83 03-30-1986 0 03-05-1978
Apr 63.5 1981 51.0 1983 89 04-13-1967 21 04-10-1982
May 74.7 1962 62.8 1981 94 05-18-1962 32 05-04-1976
Jun 79.2 1971 71.0 1974 100 06-26-1971 42 06-01-1972
Jul 82.7 1980 74.6 1967 105 07-14-1966 48 07-06-1972
Aug 81.8 1980 72.1 1967 103 08-15-1965 42 08-29-1986
Sep 76.6 1998 63.4 1994 99 09-09-1980 29 09-22-1983
Oct 65.9 1971 53.5 1988 92 10-03-1969 18 10-24-1981
Nov 54.6 1999 40.1 1976 85 11-01-2000 9 11-22-1964
Dec 45.9 1971 25.8 1983 74 12-02-1982 -13 12-22-1989
                 
Annual 61.0 1962 54.4 1978 105 07-14-1966 -21 01-21-1984
Winter 41.9 2000 28.1 1978 74 12-02-1982 -21 01-21-1984
Spring 62.2 1977 53.5 1984 94 05-18-1962 0 03-05-1978
Summer 80.1 1980 73.9 1967 105 07-14-1966 42 06-01-1972
Fall 63.6 1973 54.6 1976 99 09-09-1980 9 11-22-1964

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 6.2 22.9 1.1
Feb 0.0 3.1 16.9 0.5
Mar 0.0 0.3 11.0 0.0
Apr 0.0 0.0 2.5 0.0
May 1.2 0.0 0.0 0.0
Jun 8.2 0.0 0.0 0.0
Jul 16.4 0.0 0.0 0.0
Aug 13.2 0.0 0.0 0.0
Sep 4.6 0.0 0.1 0.0
Oct 0.1 0.0 2.2 0.0
Nov 0.0 0.1 9.5 0.0
Dec 0.0 3.3 19.3 0.4
         
Annual 43.7 13.0 84.2 2.0
Winter 0.0 12.5 58.9 2.0
Spring 1.2 0.3 13.6 0.0
Summer 37.9 0.0 0.0 0.0
Fall 4.7 0.1 11.7 0.0

Snowfall Summary

Station: 110993 BROOKPORT DAM 52, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 3.4 2.8 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.2 8.3

Snowfall Extremes

Period of Record: 1928-2006

Month High (in) Year 1-Day Max (in) Date
Jan 19.6 1978 8.0 01-17-1978
Feb 13.0 1993 6.0 02-25-1965
Mar 15.5 1960 10.0 03-09-1994
Apr 0.0 - - -
May 0.0 - - -
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 0.0 - - -
Nov 4.5 1950 4.5 11-24-1950
Dec 13.0 2004 13.0 12-22-2004
Season (Jul-Jun) 35.3 1984-1985 13.0 12-22-2004

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 1.4 1.2 0.7 0.1
Feb 1.4 1.2 0.7 0.1
Mar 0.4 0.3 0.2 0.0
Apr 0.0 0.0 0.0 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 0.0 0.0 0.0 0.0
Dec 0.7 0.5 0.3 0.0
Annual 4.2 3.1 1.7 0.3

Growing Season Summary

Station: 110993 BROOKPORT DAM 52, 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 63 114 290 538 836 1054 1214 1158 909 598 279 99 7061
45 27 57 182 394 681 904 1059 1003 759 448 175 47 5663
50 9 23 101 263 526 754 904 849 610 308 97 19 4408
55 2 6 46 153 374 604 749 695 462 190 46 7 3293
60 0 0 16 74 234 455 594 540 321 98 16 1 2322
50** 32 64 170 327 541 723 837 796 604 377 160 50 4621

**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 4/09 3/23 3/29 4/24 5/05 10/21 9/21 10/05 11/07 11/13
30 4/06 3/18 3/19 4/16 4/23 10/23 9/21 10/13 11/13 12/03
28 4/02 2/28 3/16 4/11 4/23 11/07 10/13 10/21 11/27 12/03
24 3/14 2/09 3/02 4/09 4/18 11/14 10/24 10/31 12/07 12/09
20 2/27 1/30 2/08 3/16 3/24 11/30 10/24 11/08 12/22 12/25
16 2/15 1/10 1/29 3/11 3/24 12/13 11/03 11/19 12/28 1/16

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 193 149 171 211 223
30 204 154 186 228 247
28 223 195 202 246 251
24 247 206 213 271 274
20 278 235 244 300 303
16 296 237 276 328 346

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