Historical Climate Data

Precipitation Summary

Station: 119002 WATERLOO, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 2.32 2.40 3.73 4.16 4.04 4.01 4.25 3.13 3.41 3.05 4.21 3.40 42.11

Precipitation Extremes

Period of Record: 1911-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 9.72 1916 0.07 2003 3.35 01-12-1916
Feb 5.28 1985 0.08 1917 3.00 02-01-1988
Mar 11.15 1945 0.50 1941 3.18 03-28-1977
Apr 12.81 1996 0.82 1955 6.79 04-29-1996
May 13.25 1995 0.18 1914 3.70 05-08-1961
Jun 10.08 2000 0.22 1991 5.41 06-11-1938
Jul 9.80 1958 0.07 2002 5.32 07-28-1979
Aug 12.38 1915 0.19 1930 7.03 08-20-1915
Sep 9.45 1984 0.00 2004 5.08 09-18-1986
Oct 11.79 1919 0.32 1952 6.24 10-26-1919
Nov 13.59 1985 0.39 1949 5.96 11-02-1972
Dec 9.34 1987 0.11 1955 3.80 12-10-1971
             
Annual 52.73 1973 20.04 1953 7.03 08-20-1915
Winter 17.19 1950 2.60 1954 3.80 12-10-1971
Spring 22.21 1945 3.78 1914 6.79 04-29-1996
Summer 24.47 1915 3.20 1930 7.03 08-20-1915
Fall 20.36 1984 2.31 1999 6.24 10-26-1919

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 7.5 4.8 1.3 0.5
Feb 6.8 4.5 1.5 0.6
Mar 9.9 7.1 2.7 0.8
Apr 10.4 7.4 2.5 1.1
May 10.4 7.2 2.9 1.0
Jun 9.2 6.4 2.8 1.0
Jul 8.0 5.8 2.6 1.4
Aug 7.4 5.3 2.0 0.9
Sep 7.0 4.7 2.0 0.9
Oct 8.2 5.4 2.2 0.8
Nov 9.5 6.7 2.6 1.0
Dec 8.2 5.7 2.4 1.0
         
Annual 102.7 71.1 27.6 10.9
Winter 22.5 14.9 5.1 2.1
Spring 30.7 21.7 8.1 2.9
Summer 24.7 17.6 7.5 3.2
Fall 24.6 16.7 6.8 2.7

Temperature Summary

Station 119002 WATERLOO, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 37.6 44.0 54.8 66.0 75.6 84.4 88.5 86.9 79.9 68.6 54.3 42.0 65.2
Low °F 20.3 25.1 35.1 44.6 54.7 63.8 68.1 66.2 58.6 47.0 36.2 25.1 45.4
Mean °F 29.0 34.6 45.0 55.3 65.2 74.1 78.3 76.6 69.3 57.8 45.3 33.6 55.3
HDD 1118 853 621 306 110 6 0 3 41 250 595 976 4879
CDD 0 0 0 15 114 279 412 361 168 27 1 0 1377

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

Temperature Extremes

Period of Record: 1948-2000


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 41.3 1990 15.5 1977 75 01-23-1967 -16 01-17-1977
Feb 42.7 1976 22.1 1978 83 02-13-1962 -12 02-03-1996
Mar 52.9 1973 36.5 1984 88 03-29-1985 0 03-02-1980
Apr 63.4 1948 49.3 1983 93 04-26-1989 21 04-10-1996
May 74.5 1962 60.4 1976 95 05-27-1978 30 05-03-1976
Jun 78.5 1971 69.9 1982 103 06-25-1988 42 06-01-1972
Jul 82.9 1966 74.7 1967 106 07-12-1966 47 07-06-1972
Aug 81.8 1983 70.8 1992 107 08-21-1962 45 08-13-1964
Sep 74.2 1998 63.3 1974 102 09-14-1971 34 09-23-1983
Oct 70.5 1963 51.2 1976 94 10-11-1963 22 10-25-1981
Nov 53.5 1999 36.9 1976 89 11-03-1987 3 11-30-1964
Dec 43.7 1965 20.2 1983 75 12-03-1970 -18 12-22-1989
                 
Annual 60.1 1961 53.0 1979 107 08-21-1962 -18 12-22-1989
Winter 37.3 2000 24.8 1978 83 02-13-1962 -18 12-22-1989
Spring 60.2 1977 50.9 1984 95 05-27-1978 0 03-02-1980
Summer 79.7 1980 72.8 1992 107 08-21-1962 42 06-01-1972
Fall 63.7 1963 52.2 1976 102 09-14-1971 3 11-30-1964

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 10.8 25.9 1.8
Feb 0.0 6.3 19.7 0.7
Mar 0.0 1.0 13.3 0.0
Apr 0.2 0.0 2.8 0.0
May 1.1 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 11.5 0.0 0.0 0.0
Sep 4.6 0.0 0.0 0.0
Oct 0.2 0.0 2.3 0.0
Nov 0.0 0.7 11.4 0.0
Dec 0.0 5.8 22.8 0.8
         
Annual 41.0 24.7 97.5 3.4
Winter 0.0 23.0 68.4 3.4
Spring 1.3 1.0 16.1 0.0
Summer 34.4 0.0 0.0 0.0
Fall 4.9 0.7 13.3 0.0

Snowfall Summary

Station: 119002 WATERLOO, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 4.7 3.0 1.9 0.7 0.0 0.0 0.0 0.0 0.0 0.0 1.3 3.0 14.6

Snowfall Extremes

Period of Record: 1911-2006

Month High (in) Year 1-Day Max (in) Date
Jan 18.9 1982 15.0 01-31-1982
Feb 18.5 1993 11.0 02-26-1993
Mar 23.1 1960 8.0 03-03-1960
Apr 9.0 1971 7.5 04-06-1971
May 0.0 - - -
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 0.0 - - -
Nov 12.0 1980 9.0 11-27-1980
Dec 17.9 1973 12.0 12-20-1973
Season (Jul-Jun) 40.4 1959-1960 15.0 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 1.9 0.9 0.5 0.1
Feb 1.9 0.9 0.5 0.1
Mar 1.1 0.7 0.4 0.1
Apr 0.2 0.2 0.2 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 0.6 0.4 0.3 0.1
Dec 1.5 1.0 0.6 0.1
Annual 8.1 4.6 2.9 0.6

Growing Season Summary

Station: 119002 WATERLOO, 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 37 84 240 477 787 1030 1187 1134 881 556 237 66 6685
45 15 43 148 342 633 880 1033 979 731 409 147 31 5374
50 5 18 84 224 481 730 878 824 583 278 82 13 4192
55 1 5 42 132 334 580 723 669 438 170 40 4 3140
60 0 1 18 68 205 431 569 514 302 87 15 0 2215
50** 22 52 142 282 498 700 815 775 577 336 132 38 4358

**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 4/10 3/24 3/25 4/22 5/04 10/20 10/01 10/04 11/05 11/10
30 4/07 3/18 3/23 4/19 5/04 10/27 10/09 10/12 11/07 11/12
28 4/05 3/07 3/16 4/11 4/19 11/06 10/11 10/20 12/01 12/09
24 3/20 3/06 3/09 4/09 4/11 11/16 10/23 11/03 12/03 12/22
20 3/09 2/03 2/08 3/25 3/27 11/24 11/02 11/08 12/19 12/22
16 2/18 1/10 2/03 3/12 3/25 12/09 11/02 11/10 12/22 1/12

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 193 160 175 215 226
30 207 167 187 218 235
28 215 191 197 247 269
24 239 213 218 265 284
20 265 228 238 295 311
16 286 237 254 317 348

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