Illinois weather

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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Recommended for Illinois

The weather guide for Illinois (Chicago) 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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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

When is the best time to go to Illinois?

The best time to go to Illinois (Chicago) is June based on the following average weather conditions.

Maximum daytime temperature = 22 - 30°C [remove]
Daily hours of sunshine = 10 hours or more [remove]

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Max Day Temperature (°C)

  • -1°C maximum daytime temperature in January in Illinois (Chicago)-1
  • 1°C maximum daytime temperature in February in Illinois (Chicago)1
  • 8°C maximum daytime temperature in March in Illinois (Chicago)8
  • 15°C maximum daytime temperature in April in Illinois (Chicago)15
  • 21°C maximum daytime temperature in May in Illinois (Chicago)21
  • 27°C maximum daytime temperature in June in Illinois (Chicago)27
  • 29°C maximum daytime temperature in July in Illinois (Chicago)29
  • 28°C maximum daytime temperature in August in Illinois (Chicago)28
  • 24°C maximum daytime temperature in September in Illinois (Chicago)24
  • 17°C maximum daytime temperature in October in Illinois (Chicago)17
  • 9°C maximum daytime temperature in November in Illinois (Chicago)9
  • 2°C maximum daytime temperature in December in Illinois (Chicago)2

Hours of Sunshine (daily)

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

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More about the USA

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.

What is the flight time to Illinois from the UK?

The flight time to Illinois from the UK is typically 8.5 hours.

What is the time difference between Illinois and the UK?

The time difference between Illinois and the UK is GMT-6 hours.

What is the main language spoken in Illinois?

The main language spoken in Illinois is English.

Learn a language for Illinois with Busuu*, Lingoda* and Rocket Languages*.

What is the currency in Illinois?

The currency in Illinois is the US Dollar (USD).

Send money to Illinois with Monito*, Wise* and World Remit*.

Which plugs are used in Illinois?

Illinois uses electrical plug type A + B (120 Volts).

Which side of the road do they drive on in Illinois?

They drive on the right side of the road in Illinois.

Do you need a visa for Illinois?

Yes, UK passport holders do need a visa to enter Illinois.

Check USA visa requirements for all passport holders with VisaHQ* and*.

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)

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

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