Average Annual Precipitation for Illinois





The tables below give yearly averages for rainfall plus snowfall at cities in Illinois.

Each place has a total for the amount of precipitation it usually receives in a year. There is also a count of the number of days with wet weather, when precipitation amounts to 0.01 inches (0.25 millimetres) or more.

The annual precipitation totals are averages based on weather data collected from 1991 to 2020 for the US National Centers for Environmental Information.

You can jump to a separate table for each region of the state: Chicago Area, Northern Illinois, Central Illinois and Southern Illinois.

Chicago Area

Average yearly precipitation
Days Place Inches Milli­metres
116 Aurora 39.5 1003
130 Chicago Botanical Garden 39.5 1004
127 Chicago Midway Airport 40.9 1038
126 Chicago O'Hare Airport 37.9 962
124 Elgin 39.9 1012
123 Joliet 38.0 966
111 Rochelle 36.6 929

Northern Illinois

Annual averages for rainfall plus snowfall
Days Place Inches Milli­metres
121 DeKalb 37.3 946
97 Dixon 40.5 1029
116 Freeport 38.4 974
117 Moline 38.3 972
121 Rockford 37.2 946
129 Waukegan 35.3 897

Central Illinois

Average amount of rain and snow a year
Days Place Inches Milli­metres
99 Alton 41.9 1063
96 Bloomington 38.5 979
111 Cahokia 42.8 1087
123 Champaign 40.9 1039
120 Charleston 43.8 1111
126 Danville 43.2 1098
116 Decatur 40.4 1027
113 Kankakee 41.7 1058
112 Ottawa 36.2 919
117 Peoria 37.6 954
109 Quincy 36.4 925
115 Springfield 38.0 966

Southern Illinois

Average annual precipitation
Days Place Inches Milli­metres
100 Belleville 43.4 1101
121 Carbondale 49.0 1243
115 Mt Vernon 45.0 1142
Reference

NOAA National Centers for Environmental Information (NCEI). Climate Normals.

Illinois Precipitation
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