Helena weather in September 2025

Expect 20°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Helena in September. Check more long-term weather averages for Helena in September before you book your next holiday to Montana in 2025/2026.

  • 20°C maximum daytime temperature in September in Helena20
    20°C max day temperature
  • 8 hours of sunshine per day
  • 7 days with some rainfall in September in Helena7
    7 days with some rainfall
  • 4°C minimum night-time temperature in September in Helena4
    4°C min night temperature
  • 13 hours of daylight per day in September in Helena13
    13 hours of daylight per day
  • No heat & humidity in September in Helena0
    No heat & humidity
  • 30 mm monthly rainfall in September in Helena30
    30 mm of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Helena5
    5 (Moderate) UV index

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

Daytime temperatures usually reach 20°C in Helena in September, falling to 4°C at night.

How sunny is it in Helena in September?

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

Does it rain in Helena in September?

There are usually 7 days with some rain in Helena in September and the average monthly rainfall is 30mm.

Helena September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:49 19:06
Monday, 15th September 2025 06:06 18:39
Tuesday, 30th September 2025 06:26 18:09

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