Official 1981-2010 Climate Normals City: ROMEOVILLE WFO State: IL ID: 117457 Latitude: 41.6044 Longitude: -88.0858 Elevation: 639.9 ft Temperature-Related Normals Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec High: 30.6 35.5 47.8 60.8 71.1 80.2 84.0 82.0 75.6 62.9 48.5 34.7 Mean: 23.2 27.6 38.6 50.2 60.5 69.9 74.0 72.3 65.1 52.9 40.6 27.4 Low: 15.8 19.7 29.5 39.6 49.9 59.6 64.1 62.7 54.6 43.0 32.7 20.0 CDD: 0 0 0 5 53 180 282 233 94 15 0 0 HDD: 1295 1047 817 449 192 33 2 6 91 388 732 1167 Number of Days T090: 0.0 0.0 0.0 0.0 0.8 2.9 3.9 2.0 0.8 0.0 0.0 0.0 T100: 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 T000: 3.5 1.5 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.6 T032: 28.6 25.2 20.2 5.6 0.2 0.0 0.0 0.0 0.0 3.4 13.8 26.6 ------------------------------------------------------------------------------------------ Annual Values High Temp: 59.6 F Mean Temp: 50.3 F Low Temp: 41.0 F Cooling DD: 862 Heating DD: 6220 Days above 90 (T090): 10.4 Days above 100 (T100): 0.1 Days below 0 (T000): 6.8 Days below 32 (T032): 123.6 ------------------------------------------------------------------------------------------ Precipitation-Related Normals Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Prcp: 1.93 1.78 2.77 3.96 4.26 4.34 4.71 4.07 3.13 3.41 3.46 2.25 Snow: 10.8 6.4 4.4 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.9 9.3 Number of Days P001: 10.2 8.4 11.4 11.5 12.8 11.3 9.8 9.9 7.5 10.0 9.7 10.9 P010: 5.3 4.0 6.2 7.2 7.7 7.6 6.9 7.4 4.8 5.9 4.9 5.5 P100: 0.4 0.2 0.5 1.2 1.3 1.3 0.9 1.4 0.9 0.9 0.6 0.4 S001: 7.3 5.2 3.4 0.5 0.0 0.0 0.0 0.0 0.0 0.0 1.2 7.8 S010: 3.8 1.7 1.2 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.2 3.2 S100: 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 ------------------------------------------------------------------------------------------ Annual Values Precipitation: 40.07 inches Snowfall: 32.3 inches Days precipitation at or above 0 inches (P000): 123.4 Days precipitation at or above 0.10 inches (P010): 73.4 Days Precipitation at or above 1.00 inches (P100): 10.0 Days Snowfall at or above 0.1 inches (S001): 25.4 Days Snowfall at or above 1.0 inches (S010): 10.4 Days Snowfall at or above 10.0 inches (S100): 0.2 ------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------ 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