Montana weather in September 2025

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

  • 20°C maximum daytime temperature in September in Montana (Helena)20
    20°C max day temperature
  • 8 hours of sunshine per day
  • 7 days with some rainfall in September in Montana (Helena)7
    7 days with some rainfall
  • 4°C minimum night-time temperature in September in Montana (Helena)4
    4°C min night temperature
  • 13 hours of daylight per day in September in Montana (Helena)13
    13 hours of daylight per day
  • No heat & humidity in September in Montana (Helena)0
    No heat & humidity
  • 30 mm monthly rainfall in September in Montana (Helena)30
    30 mm of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Montana (Helena)5
    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.

Top Montana destinations

Below are average maximum temperatures at popular countries, regions and places in Montana in September. Select a holiday destination to see more weather parameters.

All Montana destinations

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

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How hot is it in Montana in September?

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

How sunny is it in Montana in September?

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

Does it rain in Montana in September?

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

Montana September sunrise & sunset times

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

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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