Official 1981-2010 Climate Normals City: CAHOKIA State: IL ID: 111160 Latitude: 38.5669 Longitude: -90.1942 Elevation: 399.8 ft Temperature-Related Normals Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec High: 39.8 45.4 55.6 67.0 75.5 84.0 88.0 87.0 79.6 69.1 56.2 42.6 Mean: 30.7 35.1 45.2 56.3 65.4 74.2 78.4 76.9 68.7 57.4 45.8 33.8 Low: 21.5 24.9 34.7 45.5 55.3 64.5 68.7 66.7 57.8 45.7 35.5 24.9 CDD: 0 0 5 29 103 285 414 369 162 29 3 0 HDD: 1065 836 621 291 90 7 0 2 51 265 577 969 Number of Days T090: 0.0 0.0 0.0 0.2 0.8 5.3 12.4 10.0 2.8 0.2 0.0 0.0 T100: 0.0 0.0 0.0 0.0 0.0 0.0 0.5 0.5 0.0 0.0 0.0 0.0 T000: 1.2 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.4 T032: 26.1 21.1 12.8 2.0 0.0 0.0 0.0 0.0 0.0 2.4 11.4 23.3 ------------------------------------------------------------------------------------------ Annual Values High Temp: 65.9 F Mean Temp: 55.7 F Low Temp: 45.6 F Cooling DD: 1399 Heating DD: 4774 Days above 90 (T090): 31.6 Days above 100 (T100): 1.1 Days below 0 (T000): 2.0 Days below 32 (T032): 99.2 ------------------------------------------------------------------------------------------ Precipitation-Related Normals Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Prcp: 2.62 2.54 3.34 3.83 4.65 4.10 4.44 3.40 3.40 3.42 3.92 3.07 Snow: 5.0 3.6 1.7 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.6 4.0 Number of Days P001: 8.1 7.7 10.3 10.6 11.6 9.8 8.5 7.8 6.8 8.4 8.9 9.3 P010: 5.2 5.3 7.0 7.5 8.2 6.7 6.5 5.8 5.0 5.8 6.5 5.9 P100: 0.6 0.6 0.9 0.8 1.1 1.1 1.6 1.0 1.0 1.0 1.0 0.8 S001: 2.7 2.1 0.9 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.3 2.2 S010: 1.7 1.0 0.6 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.2 1.2 S100: 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ------------------------------------------------------------------------------------------ Annual Values Precipitation: 42.73 inches Snowfall: 15.1 inches Days precipitation at or above 0 inches (P000): 107.8 Days precipitation at or above 0.10 inches (P010): 75.4 Days Precipitation at or above 1.00 inches (P100): 11.5 Days Snowfall at or above 0.1 inches (S001): 8.3 Days Snowfall at or above 1.0 inches (S010): 4.8 Days Snowfall at or above 10.0 inches (S100): 0.0 ------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------ KEY: High - average daily high temperature, degrees F Mean - average daily mean temperature, degrees F Low - average daily low temperature, degrees F CDD - cooling degree days, base 50F HDD - heating degree days, base 50F T090 - number of Days with Temperatures above 90 degrees F T100 - number of Days with Temperatures above 100 degrees F T000 - number of Days with Temperatures below 0 degrees F T032 - number of Days with Temperatures below 32 degrees F Prcp - precipitation, inches Snow - snowfall, inches P001 - number of Days with Precipitation of 0.01 inches or more P010 - number of Days with Precipitation of 0.10 inches or more P100 - number of Days with Precipitation of 1.00 inches or more S001 - number of Days with Snowfall of 0.1 inches or more S010 - number of Days with Snowfall of 1.0 inches or more S100 - number of Days with Snowfall of 10.0 inches or more Page Source: Dr. Jim Angel, State Climatologist Illinois State Water Survey Prairie Research Institute University of Illinois Data Source: NOAA National Climatic Data Center