Sun Valley weather in September 2025

Expect 68°F daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in Sun Valley in September. Check more long-term weather averages for Sun Valley in September before you book your next holiday to Idaho in 2025/2026.

  • 68°F maximum daytime temperature in September in Sun Valley68
    68°F max day temperature
  • 9 hours of sunshine per day
  • 8 days with some rainfall in September in Sun Valley8
    8 days with some rainfall
  • 34°F minimum night-time temperature in September in Sun Valley34
    34°F min night temperature
  • 12 hours of daylight per day in September in Sun Valley12
    12 hours of daylight per day
  • No heat & humidity in September in Sun Valley0
    No heat & humidity
  • 1.0 inches monthly rainfall in September in Sun Valley1.0
    1.0 inches of monthly rainfall
  • UV (maximum) index 6 (High) in September in Sun Valley6
    6 (High) UV index

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The September weather guide for Idaho (Sun Valley) 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 Sun Valley in September?

Daytime temperatures usually reach 68°F in Sun Valley in September, falling to 34°F at night.

How sunny is it in Sun Valley in September?

There are normally 9 hours of bright sunshine each day in Sun Valley in September - that's 73% of daylight hours.

Does it rain in Sun Valley in September?

There are usually 8 days with some rain in Sun Valley in September and the average monthly rainfall is 1.0 inches.

Sun Valley September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 06:01 19:12
Monday, 15th September 2025 06:17 18:47
Tuesday, 30th September 2025 06:34 18:19

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