Chicago weather in September 2025

Expect 24°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Chicago in September. Check more long-term weather averages for Chicago in September before you book your next holiday to Illinois in 2025/2026.

  • 24°C maximum daytime temperature in September in Chicago24
    24°C max day temperature
  • 8 hours of sunshine per day
  • 9 days with some rainfall in September in Chicago9
    9 days with some rainfall
  • 12°C minimum night-time temperature in September in Chicago12
    12°C min night temperature
  • 12 hours of daylight per day in September in Chicago12
    12 hours of daylight per day
  • No heat & humidity in September in Chicago0
    No heat & humidity
  • 87 mm monthly rainfall in September in Chicago87
    87 mm of monthly rainfall
  • UV (maximum) index 6 (High) in September in Chicago6
    6 (High) UV index
  • 19°C sea temperature in September in Chicago19
    19°C sea temperature

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The September 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.

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

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More about the USA

How hot is it in Chicago in September?

Daytime temperatures usually reach 24°C in Chicago in September, falling to 12°C at night.

How sunny is it in Chicago in September?

There are normally 8 hours of bright sunshine each day in Chicago in September - that's 61% of daylight hours.

How warm is the sea around Chicago in September?

The average sea temperature around Chicago in September is 19°C.

Does it rain in Chicago in September?

There are usually 9 days with some rain in Chicago in September and the average monthly rainfall is 87mm.

Chicago September sunrise & sunset times

Browse the sunrise and sunset times for Chicago in September 2025. Select a month to view Chicago sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:17 18:23
Monday, 15th September 2025 05:31 17:59
Tuesday, 30th September 2025 05:47 17:33

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