Historical Climate Data

Precipitation Summary

Station: 116446 OLNEY 2S, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 2.84 2.73 4.35 4.38 4.76 4.07 4.13 3.55 3.09 3.34 4.39 3.65 45.28

Precipitation Extremes

Period of Record: 1890-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 12.02 1950 0.10 1986 3.17 01-01-1948
Feb 7.03 1950 0.05 1947 3.35 02-20-1891
Mar 12.04 1945 0.27 1910 6.30 03-25-1904
Apr 13.31 1893 0.99 1899 3.75 04-19-1959
May 12.79 1943 0.77 1914 5.37 05-07-1961
Jun 9.59 1945 0.46 1978 4.43 06-18-1911
Jul 11.73 1958 0.25 1901 4.55 07-10-1933
Aug 11.17 2000 0.39 1943 4.12 08-03-1924
Sep 12.23 1911 0.03 1963 6.43 09-03-1926
Oct 12.32 1919 0.13 1895 4.60 10-18-1905
Nov 12.21 1985 0.22 1999 5.34 11-14-1993
Dec 9.98 1982 0.46 1896 3.95 12-03-1982
             
Annual 63.75 1945 25.56 1936 6.43 09-03-1926
Winter 24.10 1950 3.57 1931 3.95 12-03-1982
Spring 24.60 1996 3.91 1930 6.30 03-25-1904
Summer 27.24 2000 3.61 1936 4.55 07-10-1933
Fall 19.62 1919 2.92 1999 6.43 09-03-1926

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 9.4 5.7 1.9 0.6
Feb 8.0 5.1 1.8 0.7
Mar 11.4 7.7 3.3 1.1
Apr 11.8 8.3 3.1 1.0
May 10.8 7.4 3.2 1.4
Jun 9.5 6.7 3.0 1.1
Jul 8.6 6.0 2.7 1.2
Aug 8.2 5.6 2.7 1.1
Sep 7.5 5.1 2.0 0.9
Oct 8.0 5.0 2.2 0.9
Nov 9.7 6.8 3.1 1.3
Dec 10.1 6.4 2.6 0.9
         
Annual 112.9 75.7 31.5 12.2
Winter 27.5 17.2 6.3 2.2
Spring 34.0 23.4 9.5 3.5
Summer 26.3 18.2 8.4 3.4
Fall 25.1 16.9 7.3 3.1

Temperature Summary

Station 116446 OLNEY 2S, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 36.4 42.2 53.5 64.9 74.9 84.2 87.5 85.9 79.8 68.6 53.7 41.4 64.4
Low °F 18.7 22.5 31.8 41.9 51.8 62.0 65.5 63.2 55.0 43.6 33.8 24.3 42.8
Mean °F 27.6 32.4 42.7 53.4 63.4 73.1 76.5 74.6 67.4 56.1 43.8 32.9 53.7
HDD 1161 915 693 353 141 7 0 4 53 303 638 996 5264
CDD 0 0 0 5 90 250 356 300 125 26 0 0 1152

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

Temperature Extremes

Period of Record: 1896-2006


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 41.6 1933 13.2 1918 75 01-24-1943 -24 01-19-1994
Feb 44.0 1938 20.0 1978 78 02-29-1972 -25 02-02-1951
Mar 57.3 1946 31.0 1960 89 03-24-1910 -15 03-05-1978
Apr 61.8 1925 45.4 1907 91 04-11-1930 21 04-05-1944
May 72.5 1962 57.6 1917 98 05-27-1911 29 05-01-1963
Jun 79.8 1952 68.2 1916 106 06-29-1931 36 06-16-1917
Jul 85.1 1936 72.9 1967 112 07-14-1936 45 07-01-1937
Aug 83.1 1936 68.8 1915 109 08-08-1930 41 08-31-1915
Sep 76.7 1925 60.3 1918 106 09-05-1925 27 09-30-1899
Oct 65.1 1947 47.9 1917 97 10-02-1953 17 10-29-1952
Nov 54.9 1909 36.8 1976 89 11-23-1923 -2 11-30-1929
Dec 45.3 1923 20.7 1989 74 12-02-1982 -19 12-22-1989
                 
Annual 59.9 1921 48.8 1912 112 07-14-1936 -25 02-02-1951
Winter 42.4 1932 22.0 1918 78 02-29-1972 -25 02-02-1951
Spring 59.9 1921 50.6 1984 98 05-27-1911 -15 03-05-1978
Summer 81.1 1936 71.3 1915 112 07-14-1936 36 06-16-1917
Fall 63.0 1931 51.3 1976 106 09-05-1925 -2 11-30-1929

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 11.0 25.5 2.4
Feb 0.0 5.7 19.6 1.6
Mar 0.0 1.1 14.2 0.1
Apr 0.0 0.0 4.1 0.0
May 0.9 0.0 0.2 0.0
Jun 7.3 0.0 0.0 0.0
Jul 12.5 0.0 0.0 0.0
Aug 9.0 0.0 0.0 0.0
Sep 3.8 0.0 0.0 0.0
Oct 0.1 0.0 4.1 0.0
Nov 0.0 0.5 12.6 0.0
Dec 0.0 5.9 22.1 1.1
         
Annual 33.6 24.4 103.4 5.3
Winter 0.0 22.5 67.1 5.1
Spring 0.9 1.1 18.8 0.1
Summer 29.0 0.0 0.0 0.0
Fall 3.9 0.5 16.6 0.0

Snowfall Summary

Station: 116446 OLNEY 2S, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 4.2 3.1 1.9 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.7 3.3 13.4

Snowfall Extremes

Period of Record: 1890-2006

Month High (in) Year 1-Day Max (in) Date
Jan 24.5 1918 12.0 01-15-1918
Feb 18.5 1910 11.5 02-16-1910
Mar 17.0 1960 10.0 03-13-1937
Apr 6.0 1917 5.0 04-09-1917
May 0.0 - - -
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 2.2 1925 1.5 10-23-1917
Nov 6.1 1932 5.3 11-26-1902
Dec 13.6 2000 7.3 12-25-2002
Season (Jul-Jun) 37.0 1917-1918 12.0 01-15-1918

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 1.6 1.0 0.5 0.2
Feb 1.6 1.0 0.5 0.2
Mar 1.0 0.7 0.3 0.2
Apr 0.1 0.1 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 0.4 0.3 0.2 0.0
Dec 1.7 1.1 0.7 0.2
Annual 7.1 4.9 2.7 0.7

Growing Season Summary

Station: 116446 OLNEY 2S, 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 34 70 223 465 778 1016 1164 1101 859 544 225 62 6356
45 14 33 135 328 623 866 1009 947 710 397 137 29 5080
50 5 12 75 210 469 716 854 792 561 266 75 13 3935
55 1 3 35 120 323 567 699 638 416 159 34 4 2916
60 0 0 13 57 195 418 544 483 280 79 12 0 2027
50** 17 40 133 283 499 690 802 754 567 343 126 31 4165

**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 4/14 3/25 3/31 5/08 5/12 10/11 9/22 10/02 10/21 10/25
30 4/10 3/24 3/29 4/23 5/05 10/21 10/02 10/05 11/05 11/13
28 4/07 3/18 3/24 4/18 4/23 10/24 10/04 10/13 11/12 11/23
24 3/22 2/28 3/08 4/10 4/19 11/04 10/08 10/16 11/28 12/04
20 3/12 2/22 2/27 3/20 3/26 11/19 10/24 11/02 12/10 12/22
16 2/21 12/13 2/02 3/14 3/25 12/05 11/05 11/07 12/22 1/02

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 181 144 152 198 212
30 193 163 170 214 225
28 204 175 188 225 235
24 224 191 204 257 266
20 254 222 230 283 292
16 283 238 260 317 343

Back to the Station List

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