Illinois weather

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Below are the temperatures expected today at popular destinations in Illinois. Select a destination to compare today's forecast with average weather conditions.

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

The weather guide for Illinois shows long term weather averages processed from data supplied by CRU (University of East Anglia) & today's weather forecast provided by MeteoBlue. Find out more about our data sources.

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Which is the hottest month in Illinois?

The hottest time of year in Chicago, Illinois is normally July. Expect maximum daytime temperatures to reach 29°C with moderate heat and humidity.

Which month has the most rain in Illinois?

In terms of rainfall, July is usually the wettest month in Chicago, Illinois with 100mm on average. There are normally 10 days in July with some rain.

When is it sunniest in Illinois?

The sunniest time of year in Chicago, Illinois is normally July with bright sunshine on average for 69% of daylight hours; that's 10 hours of sunshine per day.

When is the sea warmest in Illinois?

The sea is usually at its warmest in Chicago, Illinois in August when the water temperature reaches 21°C.

Metric (°C / mm)  |  Imperial (°F / inches)

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Compare Illinois weather with the USA

Below the Illinois weather 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)

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