Green Bay weather in September 2025

Expect 21°C daytime maximum temperatures in the shade with on average 7 hours of sunshine per day in Green Bay in September. Check more long-term weather averages for Green Bay in September before you book your next holiday to Wisconsin in 2025/2026.

  • 21°C maximum daytime temperature in September in Green Bay21
    21°C max day temperature
  • 7 hours of sunshine per day
  • 10 days with some rainfall in September in Green Bay10
    10 days with some rainfall
  • 10°C minimum night-time temperature in September in Green Bay10
    10°C min night temperature
  • 12 hours of daylight per day in September in Green Bay12
    12 hours of daylight per day
  • No heat & humidity in September in Green Bay0
    No heat & humidity
  • 88 mm monthly rainfall in September in Green Bay88
    88 mm of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Green Bay5
    5 (Moderate) UV index
  • 18°C sea temperature in September in Green Bay18
    18°C sea temperature

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The September weather guide for Wisconsin (Green Bay) 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 Green Bay in September?

Daytime temperatures usually reach 21°C in Green Bay in September, falling to 10°C at night.

How sunny is it in Green Bay in September?

There are normally 7 hours of bright sunshine each day in Green Bay in September - that's 54% of daylight hours.

How warm is the sea around Green Bay in September?

The average sea temperature around Green Bay in September is 18°C.

Does it rain in Green Bay in September?

There are usually 10 days with some rain in Green Bay in September and the average monthly rainfall is 88mm.

Green Bay September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:15 18:28
Monday, 15th September 2025 05:31 18:02
Tuesday, 30th September 2025 05:49 17:34

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