What is the weather like in Rocky Mountain National Park vs Yellowstone National Park in September?

In September, Rocky Mountain National Park averages 18°C high / 6°C low with about 41 mm of rain; Yellowstone National Park averages 17°C high / 1°C low with about 59 mm.

Rocky Mountain National Park vs Yellowstone National Park in September

Rocky Mountain National Park is the better pick in September — 90 vs 84 on SeasonMap's comfort score. Rocky Mountain National Park is cool, a little rain, clean air, while Yellowstone National Park is cool, a little rain, clean air.

Rocky Mountain National Park vs Yellowstone National Park — September climate, side by side

	🇺🇸 Rocky Mountain National Park	🇺🇸 Yellowstone National Park
Comfort score	90/100 (S)	84/100 (A)
Feels-like high	15°C	14°C
Avg high / low	18° / 6°	17° / 1°
Rainfall	41 mm	59 mm
Rainy days	6	11
Humidity	57%	59%
Air quality (AQI)	40	43

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

Month by month

Rocky Mountain National Park 🇺🇸 United Statescool, a little rain, clean air · best August90
Yellowstone National Park 🇺🇸 United Statescool, a little rain, clean air · best August84

Rocky Mountain National Park vs Yellowstone National Park in September — FAQ

Is September better in Rocky Mountain National Park or Yellowstone National Park?: Rocky Mountain National Park is the better pick in September — 90 vs 84 on SeasonMap's comfort score. Rocky Mountain National Park is cool, a little rain, clean air, while Yellowstone National Park is cool, a little rain, clean air.
What is the weather like in Rocky Mountain National Park vs Yellowstone National Park in September?: In September, Rocky Mountain National Park averages 18°C high / 6°C low with about 41 mm of rain; Yellowstone National Park averages 17°C high / 1°C low with about 59 mm.