Chicago weather in September 2025

Expect 75°F 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.

  • 75°F maximum daytime temperature in September in Chicago75
    75°F max day temperature
  • 8 hours of sunshine per day
  • 9 days with some rainfall in September in Chicago9
    9 days with some rainfall
  • 54°F minimum night-time temperature in September in Chicago54
    54°F 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
  • 3.4 inches monthly rainfall in September in Chicago3.4
    3.4 inches of monthly rainfall
  • UV (maximum) index 6 (High) in September in Chicago6
    6 (High) UV index
  • 66°F sea temperature in September in Chicago66
    66°F 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)  |  Imperial (°F)

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More about the USA

How hot is it in Chicago in September?

Daytime temperatures usually reach 75°F in Chicago in September, falling to 54°F 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 66°F.

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 3.4 inches.

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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