Rocky Mountain National Park in September

Rocky Mountain National Park · crowd + weather almanac

September crowd level busy

about 633,000 visits in a typical September

The 4th-busiest month of the year · median of 2016–2025 official NPS counts

September is the 4th-busiest month of the year at Rocky Mountain National Park: about 633,000 recreation visits in a typical September (15% of the year's traffic, and 75% of what the peak month, July, sees). This is a busy month, though short of the summer-peak crush. Weather-wise, September days at the Estes Park 3 Sse, CO station typically top out around 70°F with nights near 39°F, and about 1.6 inches of precipitation falls over the month.

Typical September: 633,288 recreation visits (median 2016–2025); the range across those years ran 500,019 (2020) to 784,480 (2018).
Busier than 8 of the other 11 months.
1991–2020 September normals at Estes Park 3 Sse, CO: high 70°F, low 39°F, 1.65 in precipitation, 0.5 in snow.

Typical (median) monthly recreation visits at Rocky Mountain National Park, 2016–2025. September highlighted. Source: NPS Visitor Use Statistics.

September weather (1991–2020 normals)

Typical daytime high	70°F
Typical overnight low	39°F
Precipitation (monthly normal)	1.65 in
Snowfall (monthly normal)	0.5 in
Measured at	Estes Park 3 Sse, CO (USC00052761), 3.2 mi from the park reference point, elev. 7,812 ft

Every month at Rocky Mountain

Month	Typical visits	Crowds	High / Low	Precip
January	116,141	quietest stretch	37°F / 16°F	0.8 in
February	103,129	quietest stretch	38°F / 16°F	0.7 in
March	146,083	quiet	45°F / 21°F	1.6 in
April	158,630	quiet	52°F / 26°F	2.3 in
May	296,228	quiet	61°F / 35°F	2.3 in
June	656,255	busy	74°F / 43°F	1.4 in
July	848,669	busiest stretch	80°F / 48°F	2.5 in
August	711,030	busy	78°F / 46°F	1.7 in
September	633,288	busy	70°F / 39°F	1.6 in
October	378,083	moderate	57°F / 30°F	1.1 in
November	144,220	quiet	44°F / 24°F	0.7 in
December	121,697	quietest stretch	36°F / 16°F	0.7 in

Official NPS page for Rocky Mountain →