Great Falls weather in September 2025

Expect 70°F daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Great Falls in September. Check more long-term weather averages for Great Falls in September before you book your next holiday to Montana in 2025/2026.

  • 70°F maximum daytime temperature in September in Great Falls70
    70°F max day temperature
  • 8 hours of sunshine per day
  • 7 days with some rainfall in September in Great Falls7
    7 days with some rainfall
  • 43°F minimum night-time temperature in September in Great Falls43
    43°F min night temperature
  • 13 hours of daylight per day in September in Great Falls13
    13 hours of daylight per day
  • No heat & humidity in September in Great Falls0
    No heat & humidity
  • 1.0 inches monthly rainfall in September in Great Falls1.0
    1.0 inches of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Great Falls5
    5 (Moderate) UV index

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The September weather guide for Montana (Great Falls) 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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How hot is it in Great Falls in September?

Daytime temperatures usually reach 70°F in Great Falls in September, falling to 43°F at night.

How sunny is it in Great Falls in September?

There are normally 8 hours of bright sunshine each day in Great Falls in September - that's 66% of daylight hours.

Does it rain in Great Falls in September?

There are usually 7 days with some rain in Great Falls in September and the average monthly rainfall is 1.0 inches.

Great Falls September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:44 19:05
Monday, 15th September 2025 06:03 18:36
Tuesday, 30th September 2025 06:23 18:06

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