Mount Rainier in September: Crowds, Weather & What to Pack
Best window · VisitWhen score 68/100 · #3 of 12 months
September is one of the best months of the year to visit Mount Rainier National Park: crowds run 56% of the July peak (234,962 average visits), days average 57°F with 12.6 hours of daylight. Computed from NPS and NOAA data.
Crowds in September
Mount Rainier averages 234,962 recreation visits in September — 56% of what July, the peak month, draws. Trailheads and parking fill accordingly.
Weather & daylight
Days are cool (highs average 57°F), and mornings are chilly (lows average 41°F). This is one of the wetter months (4.4″ of precipitation on average). Mid-month daylight runs 12.6 hours.
NOAA 1991–2020 monthly normals, station RAINIER PARADISE RS, WA US (4 mi from park coordinates, 5,427 ft elevation) — conditions vary inside the park, especially with elevation. Daylight computed for the 15th of September.
What to pack for Mount Rainier in September
Computed from the month's weather normals above — not a generic list.
- Warm mid-layer (fleece or light puffy) — mornings average 41°F
- Rain shell + pack cover — 4.4″ of precipitation is normal this month
- Sturdy broken-in footwear, navigation and a basic first-aid kit — every park, every month
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Also at their best in September
Other parks whose computed September verdict is a best window — same NPS × NOAA formula:
- Big Bend in September — 26% of peak crowds, highs 79°F, score 84/100
- Wrangell–St. Elias in September — 25% of peak crowds, highs 56°F, score 84/100
- Guadalupe Mountains in September — 35% of peak crowds, highs 80°F, score 81/100
- Gateway Arch in September — 29% of peak crowds, highs 81°F, score 80/100
Common questions
Is Mount Rainier crowded in September?
Moderately: September runs 56% of the July peak, averaging 234,962 visits (NPS, 2021–2025).
What is the weather like in Mount Rainier in September?
Average highs of 57°F, lows of 41°F, 4.4″ of precipitation (NOAA 1991–2020 normals, RAINIER PARADISE RS, WA US station).
What should I pack for Mount Rainier in September?
Warm mid-layer (fleece or light puffy); Rain shell + pack cover; Sturdy broken-in footwear, navigation and a basic first-aid kit — the full weather-computed list is on this page.
See also: the best national parks to visit in September · Last verified 2026-09-12