Yellowstone weather

Elevation decides most of it. Mammoth Hot Springs sits at 6,200 feet, while Yellowstone Lake is at 7,782 feet, and the National Park Service's own table shows the gap: the lake's average high runs 6°F to 9°F below Mammoth's in every month, and in winter it gets two to three times the snow. So pack for the highest place on your route, not for the town you are staying in.

Summer (June to August). Daytime is often around 70°F and occasionally 80°F at lower elevations, with cool nights. Afternoon thunderstorms are common, so start hikes early, and wildfire haze is possible in July and August. See Yellowstone weather in June for the month when snow can still linger.

Fall (September and October). Days are pleasant in September but nights turn cold, and snow becomes common up high through October. A storm can drop a foot of snow in a day, which is enough to close a road for a while.

Winter (December to March). Expect heavy snow and temperatures that stay near or below freezing all day, and often well below zero at night. Most roads carry only guided snowcoaches and snowmobiles; our Yellowstone in winter guide explains how to get around.

Spring (April and May). Winter holds on in April, and May brings melt at low elevations while snow stays on the high passes. It is the wettest stretch of the year at Mammoth, running into June. For the overall call on when to go, see the best time to visit Yellowstone.

The National Park Service's advice holds for every month: a warm jacket, rain gear and lots of layers. Add these by season.

• Summer: a warm layer for evenings, a rain shell for afternoon storms, a sun hat and sunscreen, and bear spray for trails.
• Spring and fall: a winter hat and gloves, an insulated jacket, and waterproof boots, as snow and mud are both likely.
• Winter: insulated boots, thermal base layers, a heavy parka, and a face covering for wind on a snowcoach or trail.
• Any time: a paper map or downloaded maps, since cell service is patchy, plus a list of things to do in Yellowstone for when the weather turns.

The forecast comes live from the National Weather Service; the elevations beside it are those of its forecast grid. Mammoth averages are NOAA 1991-2020 normals. Yellowstone Lake figures, access and season notes are from the National Park Service's Seasons and Weather pages, read November 2, 2026.