Yellowstone Weather in August: What to Expect and What to Pack
Monthly averages are NOAA 1991-2020 climate normals. Check the NPS alerts page for road and trail closures before you go.
By John Love I've been here · Sept 2025Facts checked against NPS.gov · Updated October 6, 2026August in Yellowstone80°F days, 46°F nights at Mammoth Hot Springs (6,195 ft), with about 1.1 inches of precipitation. Generally warm and very dry with occasional thunderstorms; wildfire smoke and haze are possible. Busy, with cool mornings at higher elevations.
How elevation changes the weather in Yellowstone
Estimated average high and low for each area in August, highest first. Air cools about 3.5°F for every 1,000 feet you climb, so the same day can feel like two different seasons.
- 8,859 ftDunraven Pass71° / 37°
- 7,782 ftYellowstone Lake74° / 40°
- 6,200 ftMammoth Hot Springs80° / 46°
Estimates based on the long-term average at Mammoth Hot Springs (6,195 ft). Check the live forecast for each area above before you go.
August compared with the months around it
| Month | Avg high | Avg low | Precipitation | Snowfall |
|---|---|---|---|---|
| July | 81°F | 48°F | 1.3 in | 0.0 in |
| August | 80°F | 46°F | 1.1 in | 0.0 in |
| September | 69°F | 39°F | 1.2 in | 0.6 in |
August is 1°F cooler than July by day, and September cools another 11°F.
Weather hazards to plan for
- Sudden snowstorms and whiteouts any month at high elevations, including Dunraven Pass and Sylvan Pass, can close roads with little notice.
- Afternoon lightning storms in July and August on exposed ridges, open valleys and lakeshores.
- Extreme winter cold, with nights well below 0°F at Lake, Old Faithful and West Yellowstone; frostbite and hypothermia risk for oversnow travelers.
- Cold water: Yellowstone Lake stays very cold year-round, and capsized boaters can quickly become hypothermic even in summer.
- Wildfire smoke and haze in mid-to-late summer, plus icy, snow-packed roads in spring and fall shoulder seasons.
What to pack for Yellowstone in August
Picked from Yellowstone's average weather in August.
Nights average 46°F at Mammoth Hot Springs, and higher campgrounds run colder. A bag rated about 10°F below the low keeps you warm.
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Afternoon thunderstorms are common here in August. A full-coverage rainfly keeps you and your gear dry, and a rain jacket belongs in every day pack.
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With nights near 46°F, hot meals and drinks make mornings much easier. Stoves are usually allowed even when campfires are banned.
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In bear country, coolers must go in your vehicle or a food locker when not in use.
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Yellowstone in August: questions
What is the weather like in Yellowstone in August?
At Mammoth Hot Springs (6,195 ft), August averages 80°F by day and 46°F at night, with about 1.1 inches of precipitation. Generally warm and very dry with occasional thunderstorms; wildfire smoke and haze are possible. Busy, with cool mornings at higher elevations.
How cold does Yellowstone get at night in August?
Nights average 46°F at Mammoth Hot Springs. Up at Dunraven Pass (8,859 ft) expect it about 9°F colder, near 37°F.
Does it snow in Yellowstone in August?
Not at Mammoth Hot Springs, where August averages no snowfall.
How does August compare with July?
August averages 80°F by day, 1°F cooler than July, and September averages 69°F.
What should I wear in Yellowstone in August?
Plan for light layers and a rain jacket. Check the forecast for each area you will visit a few days before you go.
More for your Yellowstone trip
- Yellowstone National Park guideFees, hours, maps, where to stay and a first-day plan.
- Best Time to Visit Yellowstone National ParkWhen to visit Yellowstone, month by month: road opening and closing dates, crowds, weather, wildlife timing and what is open in each season.
- How Many Days Do You Need in Yellowstone?How many days to spend in Yellowstone, with 1-, 2-, 3- and 4-day itineraries by area, NPS drive times around the Grand Loop and where to base yourself.
- Best Hikes in Yellowstone National ParkThe best day hikes in Yellowstone, from the Grand Prismatic Overlook to Mount Washburn and Avalanche Peak, with NPS distances, elevation gain and 2026 closures.
- Camping in Yellowstone National Park: Campgrounds, Reservations and TipsAll 11 Yellowstone campgrounds with 2026 dates, fees and RV limits, how six-month reservations work, the 2027 move to Recreation.gov and backcountry permits.