ClimateExplore the planning map
Climate · Sun Valley

Sun Valley in September

Warm and mostly dry, as the days shorten.

Typical weather, averaged over 30 years

September in Sun Valley is warm: highs near 74°F, lows near 44°F. Rain falls on about one day a week, and the days shorten by 1 hour 5 minutes from the first week to the last.September in Sun Valley is warm: highs near 23°C, lows near 7°C. Rain falls on about one day a week, and the days shorten by 1 hour 5 minutes from the first week to the last.

High
74°F23°Caverage
Low
44°F7°Caverage
Wet days
1a week · 21% of days
Daylight
12h 25mon average

Is September a good time to visit Sun Valley?

Yes. September is one of Sun Valley's best months (July to September).

How we judge it: every month is scored on how close its typical high comes to the range from 70°F to 80°F, how mild its nights are, and how rarely it rains. The best months are the run of months that scores best.How we judge it: every month is scored on how close its typical high comes to the range from 21°C to 27°C, how mild its nights are, and how rarely it rains. The best months are the run of months that scores best.

How September sits in the year

week by week

Temperature

Highs near 74°F in September, against 34°F to 84°F through the year.Highs near 23°C in September, against 1°C to 29°C through the year.

Chance of a wet day

21% of days in September, against 14% to 41% through the year.

Cloud cover

36% cover in September, against 24% to 63% through the year.

Daylight

12h 25m in September, against 8h 59m to 15h 23m through the year.

Week by week, lightly smoothed, with September shaded. The olive line marks the best months. Hover or tap a week for its figures.

Either side

  1. August84°29°low 51°low 11°1 wet day a weekRain on about one day a week.
  2. September74°23°low 44°low 7°1 wet day a weekRain on about one day a week.
  3. October61°16°low 34°low 1°2 wet days a weekRain on about two days a week.

Where Sun Valley sits, in September

America/Boise
this place
typical high in September 40°F4°C95°F35°C
Sunrise, mid-September
7:15 AMsets 7:50 PM
Above the sea
1,734 mhigh country
Latitude
43.7°Nnorthern hemisphere
Nearest of ours
Stanley75 km north-west

The land around Sun Valley, shaded by its typical high in September, the planning map's own layer. Hover the map for the figure at that spot; tap it on a phone. Clock times are local, for the 15th.

Elsewhere in United States in September

high · low · wet days
See September on the planning mapThe whole year in Sun Valley

Typical weather, averaged over 30 years (1995–2024), from the 11 km grid square nearest Sun Valley. Temperatures are adjusted against 66 weather stations: daytime highs read about 3.1°F cold in the source data and are raised to match, and both highs and lows are adjusted for the town's height (1,734 m) against the climate model's (2,154 m).Temperatures are adjusted against 66 weather stations: daytime highs read about 1.7°C cold in the source data and are raised to match, and both highs and lows are adjusted for the town's height (1,734 m) against the climate model's (2,154 m). Daylight is calculated from latitude. Charts are lightly smoothed week to week; the figures in the table are not. Source: Copernicus ERA5-Land reanalysis; cloud cover from NASA's MERRA-2 reanalysis, on a coarser grid of about 50 km. Contains modified Copernicus Climate Change Service information 2026; neither the European Commission nor ECMWF is responsible for any use of it. These are averages, not a forecast.

Daylight is calculated from latitude. Charts are lightly smoothed week to week; the figures in the table are not.

Source: Copernicus ERA5-Land reanalysis; cloud cover from NASA's MERRA-2 reanalysis, on a coarser grid of about 50 km. Contains modified Copernicus Climate Change Service information 2026; neither the European Commission nor ECMWF is responsible for any use of it. These are averages, not a forecast.