Official 1981-2010 Climate Normals City: CAHOKIA ST LOUIS State: IL ID: 003960 Latitude: 38.5714 Longitude: -90.1572 Elevation: 413.0 ft Temperature-Related Normals Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec High: 40.7 45.5 56.2 67.5 76.6 85.4 88.4 87.7 80.3 69.2 54.9 42.7 Mean: 31.7 36.1 45.2 55.9 65.8 74.0 77.8 76.2 67.7 57.0 45.1 34.3 Low: 22.7 26.7 34.2 44.3 55.0 62.6 67.2 64.7 55.1 44.7 35.3 26.0 CDD: 0 0 3 24 108 277 397 349 134 28 1 0 HDD: 1032 809 617 297 83 7 0 2 53 277 598 950 Number of Days T090: 0.0 0.0 0.0 0.2 1.1 8.3 12.6 9.9 3.1 0.2 0.0 0.0 T100: 0.0 0.0 0.0 0.0 0.0 0.1 0.4 0.4 0.0 0.0 0.0 0.0 T000: 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 T032: 25.4 20.3 13.3 2.7 0.0 0.0 0.0 0.0 0.0 2.8 12.3 22.5 ------------------------------------------------------------------------------------------ Annual Values High Temp: 66.3 F Mean Temp: 55.7 F Low Temp: 45.0 F Cooling DD: 1322 Heating DD: 4727 Days above 90 (T090): 35.3 Days above 100 (T100): 0.9 Days below 0 (T000): 0.8 Days below 32 (T032): 99.4 ------------------------------------------------------------------------------------------ Precipitation-Related Pseudonormals For stations with short records, linear combinations of normals from nearby sites were used to compute so-called pseudonormals. Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Prcp: 2.39 2.10 3.17 4.05 4.95 4.17 3.59 3.15 3.18 3.39 3.76 3.04 ------------------------------------------------------------------------------------------ Annual Values Precipitation: 40.94 inches ------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------ 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