Rocky Mountain National Park in September
September at Rocky Mountain National Park averages a daytime high near 70°F and an overnight low around 39°F, with about 1.7" of precipitation. Visitation runs about 1.8× the park's average month, which makes September a very busy month here.
- Average low
- 39°F
- Average high
- 70°F
Range across the year: 16°F to 80°F
- Precipitation
- 1.7 in
- Daylight
- 12.3 hours
Roughly 15% of the park's yearly visitors come in September: about 653,000 recreation visits in a typical year, based on National Park Service monthly counts from 1979 to 2025.
That makes September the 4th-busiest of the park's twelve months, sitting between the July peak (2.4×) and the February low (0.3×).
September is our recommended month at Rocky Mountain: the lightest crowds of the park's good-weather months.
The daily average of about 54°F is a comfortable range for hiking and being outdoors all day. These figures are 1991–2020 NOAA climate normals from the nearest station, about 9.3 miles from the park.
Because June, July and August together draw about 52% of annual visitors, choosing September instead steps outside that summer crush — the single biggest lever on how crowded the park feels.
You'll have about 12.3 hours of daylight in September to explore — between the 9.1-hour midwinter low and the 14.9-hour summer high.
Park-wide, 2025 drew 4,171,431 recreation visits, about flat from 4,154,349 in 2024.
How September compares with the months around it
| Month | Avg high / low | Crowds | Best-time score |
|---|---|---|---|
| August | 78°F / 46°F | 2.0× Very busy | 53 Fair |
| September | 70°F / 39°F | 1.8× Very busy | 46 Fair |
| October | 57°F / 30°F | 1.0× Average | 35 Poor |
All twelve months at Rocky Mountain, with the best time to visit.
Frequently Asked Questions
September averages a daytime high near 70°F and an overnight low around 39°F at Rocky Mountain National Park, with about 1.7 inches of precipitation. These are 1991–2020 NOAA climate normals from the nearest station, about 9.3 miles from the park, so conditions inside the park can differ, especially at other elevations.
September is very busy at Rocky Mountain National Park (about 1.8× the average month). Our best-time score rates it "Fair" at 46/100. September is our recommended month for this park.
The busiest month is July and the quietest is February. September sits at about 1.8× the park's average, or 15% of annual visitation.
A typical September sees about 653,000 recreation visits at Rocky Mountain National Park, based on National Park Service monthly counts from 1979–2025.
Where to stay near Rocky Mountain in September
Booking a September trip to Rocky Mountain National Park? Compare hotels, cabins and vacation rentals near the park with live September availability and prices.
Top-rated places to stay near Rocky Mountain
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See the full ranking of the best national parks to visit in September.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-10-11.