Average Temperatures for Illinois in December





Average temperatures for December at 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 temperatures based on weather data collected from 1991 to 2020 by the US National Centers for Environmental Information.

Chicago Area

Average temperatures in December
High °F Low °F Place High °C Low °C
36 22 Aurora 2 -6
38 22 Chicago Botanical Garden 3 -5
38 25 Chicago Midway Airport 3 -4
37 24 Chicago O'Hare Airport 3 -4
36 20 Elgin 2 -7
36 22 Joliet 2 -5
34 18 Rochelle 1 -8

Northern Illinois

Average December temperatures
High °F Low °F Place High °C Low °C
35 21 Antioch 2 -6
34 19 DeKalb 1 -7
35 20 Dixon 1 -7
33 18 Freeport 1 -8
37 21 Moline 3 -6
34 20 Rockford 1 -7
36 22 Waukegan 2 -6

Central Illinois

Normal temperatures for December
High °F Low °F Place High °C Low °C
44 27 Alton 6 -3
35 21 Bloomington 2 -6
44 29 Cahokia 7 -2
39 24 Champaign 4 -5
42 26 Charleston 6 -3
40 25 Danville 4 -4
39 25 Decatur 4 -4
38 22 Kankakee 3 -6
36 21 Ottawa 2 -6
39 23 Peoria 4 -5
39 24 Quincy 4 -5
41 25 Springfield 5 -4

Southern Illinois

Average December temperatures
High °F Low °F Place High °C Low °C
46 28 Belleville 8 -2
47 30 Cairo 8 -1
45 27 Carbondale 7 -3
43 26 Mt Vernon 6 -3
Reference

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

Illinois Temperatures
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