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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
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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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Apr
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Aug
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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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