Average Annual Temperatures in Illinois





Average annual temperatures for cities throughout Illinois are listed below.

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

The tables give the normal maximum and minimum yearly temperatures based on weather data collected from 1991 to 2020 by the US National Centers for Environmental Information.

Chicago Area

Average annual temperatures
High °F Low °F Place High °C Low °C
59 41 Aurora 15 5
59 40 Chicago Botanical Garden 15 5
61 44 Chicago Midway Airport 16 7
60 43 Chicago O'Hare Airport 15 6
59 39 Elgin 15 4
60 41 Joliet 15 5
58 38 Rochelle 14 3

Northern Illinois

Average temperatures for the year
High °F Low °F Place High °C Low °C
57 40 Antioch 14 4
58 39 DeKalb 14 4
59 40 Dixon 15 5
58 38 Freeport 14 3
62 41 Moline 16 5
59 40 Rockford 15 4
57 39 Waukegan 14 4

Central Illinois

Average yearly temperatures
High °F Low °F Place High °C Low °C
65 46 Alton 18 8
60 40 Bloomington 16 5
67 46 Cahokia 19 8
62 43 Champaign 17 6
66 45 Charleston 19 7
63 43 Danville 17 6
62 44 Decatur 17 7
61 41 Kankakee 16 5
60 41 Ottawa 15 5
62 43 Peoria 17 6
63 44 Quincy 17 6
64 44 Springfield 18 7

Southern Illinois

Annual average temperature
High °F Low °F Place High °C Low °C
69 46 Belleville 21 8
68 48 Cairo 20 9
67 45 Carbondale 19 7
64 45 Mt Vernon 18 7
Reference

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

Illinois Temperatures
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