Average Rainfall for Illinois in September





The tables below give monthly averages for rainfall during September at cities in Illinois.

Each place has a total for the amount of precipitation it usually receives this month. Most sites also have information on the number of days with wet weather. This includes the days when precipitation amounts to 0.01 inches (0.25 millimetres) or more.

The rainfall totals are averages based on weather data collected from 1981 to 2010 for the NOAA National Climatic Data Center.

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 monthly precipitation in September
Days Place Inches Milli­metres
8 Aurora 3.6 91
9 Chicago Botanical Garden 3.5 88
8 Chicago Midway Airport 3.3 84
8 Chicago O'Hare Airport 3.2 82
10 Chicago University 3.1 80
9 Elgin 3.4 86
8 Joliet 3.0 76

Northern Illinois

September averages for total rainfall
Days Place Inches Milli­metres
9 Antioch 3.5 90
9 DeKalb 3.3 83
7 Dixon 3.6 90
9 Freeport 3.7 93
8 Moline 3.1 78
8 Rockford 3.4 85
Waukegan 3.5 88

Central Illinois

Average amount of rain in September
Days Place Inches Milli­metres
7 Alton 3.3 84
7 Cahokia 3.4 86
8 Danville 2.9 74
8 Peoria 3.2 80
8 Quincy 3.3 84
7 Springfield 2.9 74
8 Urbana 3.1 80

Southern Illinois

Precipitation totals for September
Days Place Inches Milli­metres
6 Cairo 3.2 81
7 Marion 2.8 72
8 Mt Vernon 3.2 82
Reference

National Climatic Data Center. NOAA's 1981-2010 Climate Normals.

Illinois Precipitation
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