What the weather is like in September
Pleasant days and cold nights, with early snow possible up high. Roads stay open, the elk rut starts at Mammoth, bears return to roadside meadows and mosquitoes fade. Visits run about 30% below July, though some campgrounds and boat services start to close.
Against August, September runs 7°C cooler with much the same rainfall and 2.1 hours less sun a day.
These September averages are station normals for Mammoth, Yellowstone National Park (NOAA NCEI normals (sunshine: Billings, Montana, NOAA 1961-1990, via Wikipedia), 1991-2020); other parts of Yellowstone vary. Full sources below.
Yellowstone in September, on the ground
September brings pleasant days, cold nights and the first gold in the high country. Roads are typically all open, the elk rut begins at Mammoth Hot Springs and mosquitoes fade. Snow is possible at higher elevations, and frost at dawn is normal, so pack for winter mornings.
Crowds and prices in September
The National Park Service still rates September as busiest, with about 664,000 visits in an average year, but that is about 30% below July. Numbers fall through the month, so mid to late September is quieter than the first week. Rooms inside the park still sell out, so book ahead.
What to do in September
- Listen for bull elk bugling at Mammoth Hot Springs, keeping at least 25 yards away.
- Drive Lamar and Hayden valleys at dawn for bison, bears and raptors on migration.
- Hike at lower elevations, now that most trails are clear of snow and river levels have dropped.
- See fall color above 7,000 feet, which turns first.
Before you book: Campgrounds and Yellowstone Lake boat services begin closing this month, and some village services shut by mid-September, so check the operating dates for your exact week.
What to pack for Yellowstone in September
- Layers — warm afternoons, cool evenings
- A mid-weight jacket
What's on in September
- Elk rut (Mammoth Hot Springs, Grant Village) — Bull elk bugle and gather herds, often on the lawns at Mammoth. Give them extra room, and stay at least 25 yards back.
Is September the right month?
September is Yellowstone's best month of the year; the toughest, November, is two months after. If September does not fit, August is the closest month in the same best-season window. For the best balance of good conditions and smaller crowds, aim for May. See the full month-by-month breakdown for Yellowstone, or where else to go in September.
Where to stay in September
September is peak season in Yellowstone, so prices are at their highest. Book early for the best choice of rooms. For every area compared on airport trains and price, see the where to stay in Yellowstone.
- West Yellowstone$$Old Faithful and the geyser basinsThe town at the West Entrance, with the largest choice of rooms just outside the park. It is about 30 minutes to Madison Junction, then 35 to 45 minutes on to Old Faithful. Snowcoach tours also leave from here in winter.See hotels in West Yellowstone for 12–18 Sep 2027
- Gardiner$$Lamar Valley wildlife and winter tripsThe small town at the North Entrance, 15 minutes from Mammoth Hot Springs. It is on the only park road open to cars all year, so it is the best base for winter wildlife watching in Lamar Valley.See hotels in Gardiner for 12–18 Sep 2027
- Cody$$Yellowstone Lake and a town with museumsA larger town about 52 miles and 75 minutes east of the East Entrance, with its own year-round airport. It is a longer drive in, but the road through the Shoshone valley is scenic, and it works for a first or last night.See hotels in Cody for 12–18 Sep 2027
- Jackson$$Combining Yellowstone with Grand TetonThe town south of Grand Teton National Park, with a year-round airport. The South Entrance is about 57 miles and 90 minutes north, so it suits a two-park trip more than daily drives into Yellowstone.See hotels in Jackson for 12–18 Sep 2027
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Before you go
Book the rest of your September trip
Tours and tickets
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Frequently asked questions
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Sources: National Park Service: Yellowstone seasons · NOAA NCEI: Mammoth, 1991-2020 normals · National Park Service: Yellowstone safety · National Park Service: visitation statistics · National Park Service: park roads · NOAA: Billings, Montana sunshine, 1961-1990. Full provenance on the Yellowstone guide.
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