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 |
Copyright 2007 Illinois State Water Survey
Last Modified: September 11, 2007