Historical Climate Data

Precipitation Summary

Station: 116526 OTTAWA 5SW, IL


1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 1.45 1.32 2.60 3.44 4.00 4.13 3.64 3.78 3.50 2.59 2.95 2.27 35.67

Precipitation Extremes

Period of Record: 1889-2006


Month

High (in)

Year

Low (in)

Year
1-Day
Max (in)

Date
Jan 5.98 1897 0.00 1917 2.02 01-03-1897
Feb 4.76 1997 0.00 1987 2.85 02-21-1997
Mar 6.79 1948 0.12 1917 3.65 03-19-1948
Apr 9.67 1950 0.00 1917 2.81 04-25-1950
May 13.09 1892 0.00 1917 3.20 05-17-1974
Jun 10.56 1892 0.29 1988 3.57 06-23-1897
Jul 14.85 1958 0.08 1916 8.77 07-14-1958
Aug 11.21 1924 0.27 1950 6.61 08-09-1924
Sep 14.28 1926 0.31 1956 4.30 09-01-1977
Oct 9.67 1941 0.01 1964 2.66 10-11-1931
Nov 9.66 1985 0.08 1904 2.20 11-05-1902
Dec 5.75 1895 0.21 1893 2.79 12-24-1965
             
Annual 55.45 1902 21.84 1893 8.77 07-14-1958
Winter 11.20 1950 1.20 2003 2.85 02-21-1997
Spring 16.60 1947 0.12 1917 3.65 03-19-1948
Summer 26.47 1958 3.61 1991 8.77 07-14-1958
Fall 20.20 1926 1.49 1956 4.30 09-01-1977


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 8.6 4.1 0.7 0.2
Feb 6.8 3.3 0.8 0.1
Mar 9.8 6.0 1.8 0.4
Apr 11.0 6.8 2.3 0.9
May 10.8 6.9 2.6 1.2
Jun 9.7 6.6 2.6 1.2
Jul 8.7 5.8 2.5 1.0
Aug 9.0 6.1 2.3 1.2
Sep 7.7 5.4 2.0 1.0
Oct 7.9 5.0 1.8 0.4
Nov 9.2 5.9 2.0 0.7
Dec 9.0 5.2 1.3 0.6
         
Annual 108.3 67.3 22.8 8.9
Winter 24.4 12.6 2.8 0.9
Spring 31.7 19.8 6.7 2.5
Summer 27.4 18.5 7.4 3.4
Fall 24.8 16.3 5.8 2.1


Temperature Summary

Station 116526 OTTAWA 5SW, IL


1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 30.5 36.4 48.6 61.8 73.1 82.0 84.9 83.2 76.9 65.4 49.0 35.8 60.6
Low °F 12.2 17.5 28.6 38.7 49.6 59.3 63.4 61.3 52.8 40.9 29.7 18.2 39.4
Mean °F 21.4 27.0 38.6 50.3 61.4 70.7 74.2 72.3 64.9 53.2 39.4 27.0 50.0
HDD 1353 1066 820 447 186 19 3 19 90 381 769 1178 6331
CDD 0 0 0 4 72 189 287 243 85 14 0 0 894

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


Temperature Extremes

Period of Record: 1890-2006


Month
High
Mean °F

Year
Low
Mean °F

Year
1-Day
Max °F

Date
1-Day
Min °F

Date
Jan 36.6 1933 10.3 1893 68 01-23-1909 -26 01-17-1893
Feb 38.7 1998 13.6 1936 73 02-15-1921 -23 02-09-1899
Mar 50.0 1945 25.7 1960 85 03-23-1910 -8 03-08-1943
Apr 59.1 1915 43.7 1926 93 04-11-1930 12 04-02-1899
May 70.4 1977 54.6 1917 106 05-31-1934 26 05-10-1923
Jun 78.3 1934 65.7 1958 107 06-01-1934 35 06-04-1929
Jul 83.3 1901 70.2 1992 112 07-21-1901 39 07-19-1920
Aug 82.6 1947 65.2 1915 107 08-05-1918 33 08-30-1915
Sep 72.5 1978 59.8 1918 102 09-05-1899 25 09-26-1928
Oct 65.5 1963 44.0 1925 94 10-06-1963 13 10-30-1895
Nov 50.8 2001 32.4 1996 83 11-01-1950 -6 11-28-1930
Dec 38.8 1982 15.1 1983 70 12-03-1970 -23 12-28-1924
                 
Annual 59.4 1918 48.1 1893 112 07-21-1901 -26 01-17-1993
Winter 35.6 1932 18.4 1936 73 02-15-1921 -26 01-17-1993
Spring 58.2 1977 45.8 1984 106 05-31-1934 -8 03-08-1943
Summer 77.9 1901 68.4 1915 112 07-21-1901 33 08-30-1915
Fall 59.8 1963 49.1 1896 102 09-05-1999 -6 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 15.6 28.9 5.9
Feb 0.0 9.6 24.1 2.8
Mar 0.0 2.5 19.0 0.1
Apr 0.1 0.0 6.2 0.0
May 1.6 0.0 0.4 0.0
Jun 4.9 0.0 0.0 0.0
Jul 7.9 0.0 0.0 0.0
Aug 5.9 0.0 0.0 0.0
Sep 2.6 0.0 0.1 0.0
Oct 0.2 0.0 4.3 0.0
Nov 0.0 1.6 16.5 0.1
Dec 0.0 9.8 27.0 3.1
         
Annual 23.2 38.7 125.9 11.7
Winter 0.0 34.8 80.0 11.7
Spring 1.7 2.6 25.7 0.1
Summer 18.7 0.0 0.0 0.0
Fall 2.8 1.6 20.8 0.1


Snowfall Summary

Station: 116526 OTTAWA 5SW, IL


1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 8.7 5.1 2.9 0.6 0.0 0.0 0.0 0.0 0.0 0.0 1.0 6.0 24.3

Snowfall Extremes

Period of Record: 1889-2006

Month High (in) Year 1-Day Max (in) Date
Jan 30.5 1979 12.0 01-13-1979
Feb 21.5 1901 11.0 02-04-1901
Mar 24.9 1926 9.0 03-31-1926
Apr 22.4 1926 11.1 04-18-1926
May 0.3 1923 0.3 05-09-1923
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.2 1942 0.2 09-25-1942
Oct 2.0 1967 2.0 10-27-1967
Nov 9.3 1951 5.6 11-17-1926
Dec 21.2 1951 12.0 12-23-1961
Season (Jul-Jun) 72.6 1925-1926 12.0 12-23-1961

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 3.3 2.3 1.2 0.0
Feb 3.3 2.3 1.2 0.0
Mar 1.6 1.0 0.5 0.2
Apr 0.3 0.2 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 0.6 0.3 0.2 0.1
Dec 3.5 2.3 1.3 0.2
Annual 14.4 9.2 4.9 0.9


Growing Season Summary

Station: 116526 OTTAWA 5SW, 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 5 23 124 354 689 936 1071 1016 770 441 132 21 5578
45 1 7 67 233 537 788 918 863 622 303 70 9 4417
50 0 1 34 137 390 640 766 710 477 188 33 3 3378
55 0 0 14 71 256 493 614 558 336 103 13 1 2459
60 0 0 5 32 148 348 461 406 213 45 3 0 1664
50** 3 14 77 214 427 625 732 687 491 269 74 11 3626

**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 4/21 3/27 4/07 5/10 5/29 10/16 9/23 10/04 11/03 11/04
30 4/14 3/26 4/04 4/28 5/08 10/21 9/22 10/05 11/09 11/20
28 4/10 3/20 3/24 4/23 4/26 11/01 10/02 10/11 11/17 11/20
24 4/03 2/22 3/15 4/10 4/22 11/06 10/20 10/24 11/21 11/25
20 3/20 2/21 3/04 4/08 4/09 11/20 10/31 11/04 12/08 12/22
16 3/12 2/13 2/18 4/01 4/09 12/02 11/02 11/13 12/16 12/22

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 177 142 153 200 207
30 194 150 165 212 225
28 204 161 178 225 245
24 219 194 203 249 256
20 246 208 218 268 283
16 265 229 237 286 304

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