What's the Weather In Yellowstone in August

Yellowstone Weather in Late August: What to Expect and How to Prepare

If you're headed to Yellowstone around this time, you're in for a beautiful—and sometimes unpredictable—experience. Late August sits right between summer's warmth and fall's crispness. Here’s how the weather usually unfolds and what you’ll want to pack.

Warm Days, Cool Nights

Late August in Yellowstone often brings pleasant, mild days. Daytime highs generally hover between 70°F and 80°F (about 21–27°C), especially in lower elevations. It’s the kind of weather perfect for hiking in a t-shirt, fishing by the river, or wandering the geyser basins.

But come evening, the air cools down fast. Nighttime temperatures tend to dip into the upper 30s to low 40s°F (around 4°C). If you're camping or planning early morning strolls, you’ll definitely appreciate a warmer layer when the sun’s not out yet.

Afternoon Showers Make an Appearance

August isn’t immune to those classic mountain weather moments. Afternoon thunderstorms can roll in quite suddenly—brief but often dramatic. They usually make a quick exit, so a lightweight rain jacket or poncho in your pack is a smart move, just in case.

Elevation Makes a Difference

Yellowstone isn’t flat. The park stretches from around 6,000 to over 11,000 feet in elevation. That means weather can change depending on where you are. Lower spots like Lamar or Hayden Valleys stay warmer, while higher trails—say, near Mount Washburn—feel noticeably cooler. The higher you go, the more wind and chill you’ll face. Layers become your best friend.

Long, Sunny Days—With High UV

August still offers generous hours of daylight—often around 14 hours total. That means long mornings and evenings to explore. But remember, at elevation, the sun’s intensity climbs. UV levels often rate as “very high,” so pack sunscreen, sunglasses, and maybe a wide-brimmed hat—even if temps don’t feel sweltering.

Wildlife Is Buzzing

Wildlife viewing is at its peak. Bison and elk are getting into their mating season, complete with bugles, tussles, and big herds moving across the valleys. It’s a breathtaking scene—but remember, these are wild animals. Give them space and keep your distance.

Bears, too, are busy foraging and can appear near roads or trails. Be thoughtful about food storage and always carry bear spray if you're hiking.

Meanwhile, other creatures—like wolves, mountain lions, and lynx—generally stay up in the higher, quieter country, though early mornings and evenings might offer rare glimpses.

What Should You Pack?

• T-shirts or light long-sleeve shirt for daytime warmth

• Fleece or jacket for chilly early mornings and evenings

• Rain shell or poncho for surprise showers

• Hat and sunglasses for UV protection

• Sunscreen

• Bear spray and bear-aware knowledge

• Reusable water bottle to stay hydrated at altitude

• Daypack with layers and snacks

• Optional: binoculars or camera for wildlife watching

Yellowstone is an unpredictable place, so you never quite know what to expect but it helps to have a general idea. Let Old Faithful and Friends help you plan your trip today!