Early autumn · Weather & things to do

Rocky Mountain NP in September

Rocky Mountain NP cools off: highs slip to 63°F (17°C), from 71°F in August, with lows of 35°F (2°C) and about 1.7 in (42 mm) of rain.

At 93/100 for comfort (2nd of 12), it's one of the best months to visit.

What to do in September Compare all 12 months

Rocky Mountain NP, Colorado, United States

Avg high: 63°F (17°C)
Avg low: 35°F (2°C)
Rain: 1.7 in (42 mm)
Humidity: 52%
Cloud cover: 46%
Daylight: ~12 h 15 min
Comfort score: 93/100 · Great

What September feels like

Days are mild at around 63°F (17°C): comfortable for walking all day, with a layer for the evening.

There's a big swing between day and night, about 16°C (29°F), so mornings and evenings feel much cooler than the afternoon.

About 1.7 in (42 mm) of rain falls in a typical year's September.

Rocky Mountain NP: September compared with the months either side
	August	September	October
Avg high	71°F22°C	63°F17°C	48°F9°C
Avg low	43°F6°C	35°F2°C	24°F-4°C
Rain/snow	1.7 in44 mm	1.7 in42 mm	1.7 in43 mm
Daylight	13 h 36 min	12 h 15 min	10 h 54 min
Comfort	91	93	64

Plan around September

September is one of Rocky Mountain NP's best months on the climate data.

Last of the best-scoring months: by October, the score drops to 64/100.
Comfort holds steady from August (91 → 93/100).

September sits inside the Jun – Sep window our Colorado Rockies route recommends.

What to pack for September

A warm layer for eveningsnights drop to 35°F
Comfortable walking shoesmost picks involve some walking

What to do in Rocky Mountain NP in September

September is good outdoor weather here, so these picks lean toward the open air.

Photo: Arnold Thallheimer, HABS photographer · Public domain
Moraine Park
Wide meadow where elk gather, especially during the fall rut.
Why now Our curated notes say it's best dusk, Sep–Oct.
OutdoorsEast sideFree45 minDusk, Sep–Oct
Photo: martina gressani · Google
Trail Ridge Road
48-mile drive topping out at 12,183 feet, with tundra overlooks the whole way.
Why now Our curated notes say it's best Jun–Sep morning.
DoPark interiorFree180 minJun–Sep morning
Photo: Jacob West · Google
Bear Lake
Flat half-mile loop around a subalpine lake under Hallett Peak, and the trailhead for the park's classic hikes.
Why now September scores 93/100 for comfort, good conditions for being outside.
OutdoorsBear Lake RoadFree45 minEarly morning
Photo: Jeffrey Lebowski · Google
Estes Park Brewery
Estes Park's longtime brewpub, open since 1993, for post-hike pints and pub food.
DrinkEstes Park$60 minLate afternoon
Photo: Hank Johnson · Google
Bird & Jim
Estes Park restaurant near the Beaver Meadows entrance, with seasonal mountain cooking and a patio.
Why now Highs near 63°F and 1.7 in of monthly rain make this an easy outdoor pick.
EatEstes Park$$75 minDinner

Nearby in September

Denver in September~56 mi · highs 82°F, 1.4 in rain · 10°C (18°F) warmer by day, about as wet
Vail in September~60 mi · highs 67°F, 1.7 in rain · 2°C (4°F) warmer by day, about as wet
Breckenridge in September~62 mi · highs 62°F, 1.7 in rain · similar daytime temperatures, about as wet
Aspen in September~100 mi · highs 69°F, 1.8 in rain · 3°C (5°F) warmer by day, about as wet

NASA POWER 2001–2025 monthly averages on a ~50 km grid, temperatures adjusted from the grid cell's ~2,670 m to Rocky Mountain NP's ~2,918 m elevation (standard lapse rate). Comfort scores weigh temperature, rain, humidity and cloud: see how we score each month. Check a forecast before you go.