Idaho weather in September 2025

Expect 25°C daytime maximum temperatures in the shade with on average 10 hours of sunshine per day in Idaho in September. Check more long-term weather averages for Idaho in September before you book your next holiday to Idaho in 2025/2026.

  • 25°C maximum daytime temperature in September in Idaho (Boise)25
    25°C max day temperature
  • 10 hours of sunshine per day
  • 4 days with some rainfall in September in Idaho (Boise)4
    4 days with some rainfall
  • 8°C minimum night-time temperature in September in Idaho (Boise)8
    8°C min night temperature
  • 12 hours of daylight per day in September in Idaho (Boise)12
    12 hours of daylight per day
  • No heat & humidity in September in Idaho (Boise)0
    No heat & humidity
  • 19 mm monthly rainfall in September in Idaho (Boise)19
    19 mm of monthly rainfall
  • UV (maximum) index 6 (High) in September in Idaho (Boise)6
    6 (High) UV index

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The September weather guide for Idaho (Boise) 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 Idaho destinations

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

All Idaho destinations

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

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How hot is it in Idaho in September?

Daytime temperatures usually reach 25°C in Boise, Idaho in September with no heat and humidity, falling to 8°C at night.

How sunny is it in Idaho in September?

There are normally 10 hours of bright sunshine each day in Boise, Idaho in September - that's 80% of daylight hours.

Does it rain in Idaho in September?

There are usually 4 days with some rain in Boise, Idaho in September and the average monthly rainfall is 19mm.

Idaho September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 06:09 19:19
Monday, 15th September 2025 06:25 18:54
Tuesday, 30th September 2025 06:42 18:27

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