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.

Best time to visit Illinois

Q: When is the best time to visit Illinois?

The best time to visit Illinois (Chicago) is June based on the following average weather conditions. Maximum daytime temperature = 22 - 30°C. Daily hours of sunshine = 10 hours or more.

Q: 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.

Q: 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.

Q: 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.

Find the best time to visit Illinois and plan your perfect trip in 2025/2026. Get holiday inspiration, weather guides, travel advice and find great deals.

Illinois by month

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

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Destination

Top Illinois destinations

Below are the temperatures expected today at popular countries, regions and places in Illinois. Select a destination to compare today's forecast with average weather conditions.

26
Springfield
23
Chicago

All Illinois destinations

When is the best time to visit Illinois?

The best time to visit 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]

Change the criteria to reflect your weather preferences.

0.5
Jan
1
Feb
1.5
Mar
1.5
Apr
4
May
5
Jun
4.5
Jul
4.5
Aug
4
Sep
1.5
Oct
0.5
Nov
0
Dec

Change criteria

Max Day Temperature (°C)

-1
Jan
1
Feb
8
Mar
15
Apr
21
May
27
Jun
29
Jul
28
Aug
24
Sep
17
Oct
9
Nov
2
Dec

Hours of Sunshine (daily)

4
Jan
5
Feb
6
Mar
7
Apr
9
May
10
Jun
10
Jul
9
Aug
8
Sep
6
Oct
4
Nov
3
Dec

Best time to visit

Destination

Daytime temperature

Sunshine hours

Sea temperature

Monthly rainfall

Days with some rain

Heat & humidity

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.

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

More about Illinois

Explore our complete guide to Illinois with the latest travel advice for travellers and holidaymakers including official updates and local travel tips for Illinois.

Essential travel guide
Travel guidance
Travel health
Travel features
Top travel deals
FAQs

Illinois travel guide - essential info

Below is a beginner's guide to Illinois with essential travel facts such as dominant language spoken, typical flight time from the UK and the local currency. You can also check whether visas are required and what plug adapter you need to pack.

Illinois - quick facts
Flight time^✝	8.5 hours
Time difference	UK -6 hours
Language(s)	English
Currency	US Dollar
Electricity	A + B plug (120V)
Driving side	Right
Visa^✝	Yes

Why visit Illinois?

Considering a holiday to the Illinois? Here are some of the very good reasons it makes such a wonderful holiday destination such as for its culture to ensure you get the most out of your 2025/2026 escape.

Culture

Illinois tourist information

Illinois Department of Commerce

✝ = Typical flight time from the UK and visa requirements for UK travellers.

Travelling to Illinois?
Holidays Hotels Flights eSIMs Travel insurance

Illinois travel guidance

Check the latest travel guidance and advice on visiting Illinois from official government sources (in english) from around the world including entry requirements and travel restrictions.

UK traveller advice for the Illinois - UK FCDO
Irish traveller advice for the Illinois - Department of Foreign Affairs, Ireland
Canadian travel advice for the Illinois - Government of Canada
Safe travel advisories for the Illinois - Ministry of Foreign Affairs, New Zealand
Smarter traveller advice for the Illinois - Department of Foreign Affairs, Australia

Learn more about the current safety and security risks from terrorism, natural disasters and more. Read about the local laws and customs to consider when travelling around Illinois.

Note: UK FCDO - UK Foreign, Commonwealth & Development Office

Illinois travel health

Find out more about staying safe when travelling to Illinois with the latest guidance on required vaccinations and recommended medication to take with you.

Vaccines & medicines for the Illinois - CDC
Health & vaccinations for the Illinois - TravelHealthPro, NaTHNac
How to stay safe & healthy in the Illinois - Fit for Travel, Public Health Scotland

Check out the general travel tips for staying safe and healthy in Illinois, risks of preventable diseases and what to pack.

Note: CDC - Centers for Disease Control and Prevention

Illinois travel features

Do you want to learn more about Illinois? Read our latest features covering travel tips and insider destination guides on where to go and what to do in Illinois.

11 things to do in Chicago

Illinois FAQs

Read our frequently asked questions about travelling to Illinois including the current entry restrictions, driving side, electrical plugs used and much more.

Which month has the most rain in Illinois?

In terms of rainfall, January is usually the wettest month in Chicago, Illinois with 0mm on average. There are normally no days in January with some rain.

When is it sunniest in Illinois?

The sunniest time of year in Chicago, Illinois is normally January with bright sunshine on average for 0% of daylight hours; that's 0 hours of sunshine per day.

When is the sea warmest in Illinois?

The sea is usually at its warmest in Chicago, Illinois in January when the water temperature reaches 0°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 UK time-6 hours.

What is the main language spoken in Illinois?

The main language spoken in Illinois is English.

Learn a language for Illinois with Rosetta Stone^*, Busuu^* and Rocket Languages^*.

What is the currency in Illinois?

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

Send money to Illinois with TransferGo^*.

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.

Find out more about driving in USA with International Drivers Association^*.

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^*.

Illinois travel deals

Holidays to Illinois

Check out the latest deals, discount codes and special offers on holidays to Illinois in 2025/2026. Pay low deposits and save with last minute holiday availability and free kids places.