Average Precipitation for Illinois in May





The tables below give monthly averages for rainfall plus snowfall during May at cities in Illinois.

Each place has a total for the amount of precipitation it usually receives this month. 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 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 monthly precipitation in May
Days Place Inches Milli­metres
13 Aurora 4.9 123
13 Chicago Botanical Garden 4.8 123
12 Chicago Midway Airport 4.8 121
13 Chicago O'Hare Airport 4.5 114
13 Elgin 5.1 130
12 Joliet 4.5 115
13 Rochelle 4.7 119

Northern Illinois

May averages for total rainfall plus snowfall
Days Place Inches Milli­metres
13 DeKalb 4.8 122
11 Dixon 4.8 122
13 Freeport 4.4 111
12 Moline 4.7 119
13 Rockford 4.2 106
14 Waukegan 3.9 100

Central Illinois

Average amount of rain and snow in May
Days Place Inches Milli­metres
11 Alton 5.5 139
11 Bloomington 4.5 114
12 Cahokia 4.8 122
13 Champaign 4.8 121
13 Charleston 4.5 115
13 Danville 4.6 118
13 Decatur 5.0 126
12 Kankakee 5.2 131
12 Ottawa 4.5 114
13 Peoria 4.7 119
13 Quincy 4.6 116
13 Springfield 4.5 115

Southern Illinois

Precipitation totals for May
Days Place Inches Milli­metres
12 Belleville 5.1 128
13 Carbondale 5.2 132
13 Mt Vernon 5.1 129
Reference

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

Illinois Precipitation
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