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Illinois weather by month
Check out Illinois weather averages by month. Compare detailed monthly climate statistics including temperature, rainfall and sunshine figures.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Maximum daytime temperature °C | ||||||||||||
| Hours of sunshine (daily) | ||||||||||||
| Days with some rainfall | ||||||||||||
| Sea temperature °C |
More about Illinois
Illinois by month
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Recommended for Illinois
The climate guide for Illinois (Chicago) shows long term monthly weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.
Top Illinois destinations
Below are average maximum temperatures at popular countries, regions and places in Illinois for next month - December. Select a destination to see the climate guide for all months of the year.
All Illinois destinations
Metric (°C / mm) | Imperial (°F / inches)
Tropical storm risk: Illinois hurricane season
% of month affected by tropical storms
Jan
Feb
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Aug
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Dec
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Compare Illinois with the USA
Below the Illinois chart shows average maximum daytime temperature for Illinois, USA (Chicago) and the USA (Washington).
Maximum daytime temperature (°C)
Illinois, USA (Chicago)
USA (Washington)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Metric (°C / mm) | Imperial (°F / inches)
Compare more Illinois weather >>
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