Yellowstone in September: Crowds, Weather & What to Pack
Peak crowds · VisitWhen score 64/100 · #7 of 12 months
September is peak season — expect the year's biggest crowds at Yellowstone National Park: crowds run 86% of the July peak (796,027 average visits). Weather: highs average 61°F and lows 30°F, with 1.6″ of precipitation and 12.6 hours of daylight. Computed from NPS and NOAA data.
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Bring for Yellowstone in September
- Insulated jacket, beanie and glovesSee it on AmazonWhy: nights average 30°F, below freezing.
- Bear spraySee it on AmazonWhy: recommended by the park in grizzly country (check current park regulations before you carry).
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Crowds in September
Yellowstone averages 796,027 recreation visits in September — 86% of what July, the peak month, draws. Plan lodging and entries with that in mind — book early and start days at dawn.
Weather & daylight
Daytime temperatures are comfortable (highs average 61°F), and nights drop below freezing (lows average 30°F). It is typically dry (1.6″ of precipitation). Mid-month daylight runs 12.6 hours.
NOAA 1991–2020 monthly normals, station YELLOWSTONE LAKE, WY US (6 mi from park coordinates, 7,835 ft elevation) — conditions vary inside the park, especially with elevation. Daylight computed for the 15th of September.
What to pack for Yellowstone in September
Computed from the month's weather normals above — not a generic list.
- Insulated jacket, beanie and gloves — nights average 30°F, below freezing
- Sturdy broken-in footwear, navigation and a basic first-aid kit — every park, every month
- Bear spray — recommended by the park in grizzly country (check current park regulations before you carry)
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Looking for a better window? The computed best months for Yellowstone are May and June.
Also at their best in September
Other parks whose computed September verdict is a best window — same NPS × NOAA formula:
- 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
- Isle Royale in September — 39% of peak crowds, highs 65°F, score 79/100
Common questions
Is Yellowstone crowded in September?
Yes — September runs 86% of Yellowstone's peak, averaging 796,027 recreation visits (NPS, 2021–2025).
What is the weather like in Yellowstone in September?
Average highs of 61°F, lows of 30°F, 1.6″ of precipitation (NOAA 1991–2020 normals, YELLOWSTONE LAKE, WY US station).
What should I pack for Yellowstone in September?
Insulated jacket, beanie and gloves; Sturdy broken-in footwear, navigation and a basic first-aid kit; Bear spray — the full weather-computed list is on this page.
See also: the best national parks to visit in September · Last verified 2026-09-24