Average Temperatures and Rainfall for Illinois

Average annual temperatures for Illinois (11°C/52°F) are slightly below the average for United States (13°C/55°F).

Average annual rainfall for Illinois (1,154mm/45 inches) is significantly above the average for United States (1,039mm/41 inches).

What is the warmest or hottest month in Illinois?

July is the hottest or warmest month in Illinois, with an average maximum temperate of 30°C/86°F.

What is the coldest or coolest month in Illinois?

January is the coolest or coldest month in Illinois, with an average minimum temperate of -8°C/18°F.

What is the most rainy or wettest month in Illinois?

May is the wettest or most rainy month in Illinois, with an average rainfall of 145mm/6 inches.

What is the least rainy or driest month in Illinois?

January is the driest or least rainy month in Illinois, with an average rainfall of 56mm/2 inches.

What is the warmest or hottest place in Illinois?

Springfield is the hottest or warmest place in Illinois, with an average maximum temperate of 12°C/54°F.

What is the coldest place in Illinois?

Elgin is the coldest place in Illinois, with an average maximum temperate of 9°C/48°F.

What is the most rainy or wettest place in Illinois?

Chicago is the most rainy or wettest place in Illinois, with an average annual rainfall of 1,222mm/48 inches.

What is the least rainy or driest place in Illinois?

Wheaton is the least rainy or driest place in Illinois, with an average annual rainfall of 928mm/37 inches.

Average Monthly Temperatures
Average Maximum Temperature Average Minimum Temperature
Average Monthly Rainfall
PlaceMin TempMax TempAvg TempRainfall
Albany Park 7 16 12 1,012
Arlington Heights 4 14 9 1,133
Aurora 5 15 10 1,160
Belmont Cragin 7 16 12 1,012
Berwyn 7 16 11 1,222
Bloomington 5 17 11 1,101
Champaign 6 17 12 1,031
Chicago 7 16 11 1,222
Chicago Lawn 7 16 11 1,222
Cicero 7 16 11 1,222
Decatur 6 18 12 1,012
Des Plaines 6 15 11 1,132
Edgewater 7 16 12 1,012
Elgin 4 14 9 1,173
Evanston 6 15 11 1,132
Hoffman Estates 4 14 9 1,173
Irving Park 7 16 12 1,012
Joliet 6 16 11 1,185
Lincoln Park 7 16 11 1,222
Logan Square 7 16 11 1,222
Mount Prospect 4 14 9 1,173
Naperville 5 15 10 928
Near North Side 7 16 11 1,222
Normal 5 17 11 1,101
North Peoria 7 17 12 1,149
Oak Lawn 7 16 11 1,222
Oak Park 7 16 11 1,222
Palatine 4 14 9 1,133
Peoria 7 17 12 1,149
Portage Park 7 16 12 1,012
Rockford 3 15 9 1,097
Rogers Park 7 16 12 1,012
Schaumburg 4 14 9 1,173
Skokie 6 15 11 1,132
South Lawndale 7 16 11 1,222
South Shore 7 16 11 1,222
Springfield 7 18 12 1,129
Tinley Park 7 16 11 1,222
Uptown 7 16 12 1,012
Waukegan 4 14 9 1,133
West Ridge 7 16 12 1,012
West Town 7 16 11 1,222
Wheaton 5 15 10 928