Sun Valley weather in September 2025

Expect 20°C 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.

  • 20°C maximum daytime temperature in September in Sun Valley20
    20°C max day temperature
  • 9 hours of sunshine per day
  • 8 days with some rainfall in September in Sun Valley8
    8 days with some rainfall
  • 1°C minimum night-time temperature in September in Sun Valley1
    1°C 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
  • 26 mm monthly rainfall in September in Sun Valley26
    26 mm of monthly rainfall
  • UV (maximum) index 6 (High) in September in Sun Valley6
    6 (High) UV index

More about Sun Valley

Sun Valley by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recommended for Idaho

  • Save on river cruises in 2024 with Avalon Waterways
  • Book river cruises in Europe, Asia, Africa & Americas
  • Filter deals by promotion, month, destination & more

Expires at 23:59 on Tuesday 31st Dec 2024 · View all Avalon Waterways offers

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 / mm)  |  Imperial (°F / inches)

Back to top

More about the USA

How hot is it in Sun Valley in September?

Daytime temperatures usually reach 20°C in Sun Valley in September, falling to 1°C 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 26mm.

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

Related posts

Popular travel offers

Explore holidays in the sun for less

More holidays

Airport parking

More parking

Airport lounges

More lounges

Top ^