Average Temperatures for Illinois in August





Average temperatures for August 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 August temperatures in °F
High °F Low °F Place High °C Low °C
82 63 Aurora 28 17
82 62 Chicago Botanical Garden 28 17
83 67 Chicago Midway Airport 28 19
83 65 Chicago O'Hare Airport 28 18
82 61 Elgin 28 16
82 63 Joliet 28 17
81 60 Rochelle 27 15

Northern Illinois

Average August temperatures
High °F Low °F Place High °C Low °C
81 63 Antioch 27 17
81 61 DeKalb 27 16
81 62 Dixon 27 17
81 60 Freeport 27 16
84 63 Moline 29 17
82 62 Rockford 28 17
80 61 Waukegan 27 16

Central Illinois

Normal temperatures for August
High °F Low °F Place High °C Low °C
86 67 Alton 30 20
83 61 Bloomington 28 16
88 66 Cahokia 31 19
84 64 Champaign 29 18
87 64 Charleston 30 18
84 63 Danville 29 17
84 65 Decatur 29 18
83 63 Kankakee 28 17
82 62 Ottawa 28 17
85 64 Peoria 29 18
85 65 Quincy 29 18
85 64 Springfield 30 18

Southern Illinois

Average temperatures in August
High °F Low °F Place High °C Low °C
89 65 Belleville 32 19
88 68 Cairo 31 20
87 65 Carbondale 31 18
85 65 Mt Vernon 29 18
Reference

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

Illinois Temperatures
Back to Top