Yellowstone in September: Crowds, Weather & What to Pack
Peak crowds · VisitWhen score 64/100 · #7 of 12 months
September is peak season — the 4th-busiest month of the year, 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).
- Sturdy, broken-in hiking bootsSee it on AmazonWhy: every park, every month.
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Yellowstone in September: what the park service says
September is the last full month with every Yellowstone road open. On the projected 2027 schedule, Dunraven Pass and the Beartooth Highway close first, on October 11 (Dunraven may stay open longer if the weather allows), and most of the rest of the park road system closes to cars on October 31. So a late-September trip can still use every road, but check the road status page if an early storm moves in.
Source: NPS, checked 2026-11-05.
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). See every month at Yellowstone.
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). Compare it with other national parks in September.
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. Going in October instead? Yellowstone in October has its own list.
See also: the best national parks to visit in September · Last verified 2026-09-24