Illinois weather in October 2025

Expect 17°C daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in Illinois in October. Check more long-term weather averages for Illinois in October before you book your next holiday to Illinois in 2025/2026.

  • 17°C maximum daytime temperature in October in Illinois (Chicago)17
    17°C max day temperature
  • 6 hours of sunshine per day
  • 9 days with some rainfall in October in Illinois (Chicago)9
    9 days with some rainfall
  • 6°C minimum night-time temperature in October in Illinois (Chicago)6
    6°C min night temperature
  • 11 hours of daylight per day in October in Illinois (Chicago)11
    11 hours of daylight per day
  • No heat & humidity in October in Illinois (Chicago)0
    No heat & humidity
  • 68 mm monthly rainfall in October in Illinois (Chicago)68
    68 mm of monthly rainfall
  • UV (maximum) index 4 (Moderate) in October in Illinois (Chicago)4
    4 (Moderate) UV index
  • 14°C sea temperature in October in Illinois (Chicago)14
    14°C sea temperature

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The October weather guide for Illinois (Chicago) shows long term 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 in October. Select a holiday destination to see more weather parameters.

All Illinois destinations

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

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More about the USA

How warm is it in Illinois in October?

Daytime temperatures usually reach 17°C in Chicago, Illinois in October, falling to 6°C at night.

How sunny is it in Illinois in October?

There are normally 6 hours of bright sunshine each day in Chicago, Illinois in October - that's 56% of daylight hours.

How warm is the sea around Illinois in October?

The average sea temperature around Chicago, Illinois in October is 14°C.

Does it rain in Illinois in October?

There are usually 9 days with some rain in Chicago, Illinois in October and the average monthly rainfall is 68mm.

Illinois October sunrise & sunset times

Browse the sunrise and sunset times for Illinois in October 2025. Select a month to view Illinois sunrise and sunset times for the next 12 months. The Illinois sunrise and sunset times shown below are for Chicago.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Wednesday, 1st October 2025 05:48 17:32
Thursday, 16th October 2025 06:04 17:07
Friday, 31st October 2025 06:22 16:46

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