What is the weather like in Big Sky vs Sun Valley in September?

In September, Big Sky averages 19°C high / 7°C low with about 63 mm of rain; Sun Valley averages 22°C high / 3°C low with about 30 mm.

Big Sky vs Sun Valley in September

Big Sky is the better pick in September — 23 vs 18 on SeasonMap's comfort score. Big Sky is nice, a little rain, clean air, while Sun Valley is nice, dry, clean air.

Big Sky vs Sun Valley — September climate, side by side

	Big Sky	Sun Valley
Comfort score	23/100 (F)	18/100 (F)
Feels-like high	17°C	19°C
Avg high / low	19° / 7°	22° / 3°
Rainfall	63 mm	30 mm
Rainy days	10	5
Humidity	60%	52%
Air quality (AQI)	39	40

Monthly climate normals (ERA5 reanalysis). Comfort scores are SeasonMap estimates.

Big Sky vs Sun Valley in September — FAQ

Is September better in Big Sky or Sun Valley?: Big Sky is the better pick in September — 23 vs 18 on SeasonMap's comfort score. Big Sky is nice, a little rain, clean air, while Sun Valley is nice, dry, clean air.
What is the weather like in Big Sky vs Sun Valley in September?: In September, Big Sky averages 19°C high / 7°C low with about 63 mm of rain; Sun Valley averages 22°C high / 3°C low with about 30 mm.