The Weather Reality
Here's the thing about Yellowstone national park weather that catches most first-time visitors off guard: it can snow during any month of the year. July included. August included. You can stand at a boardwalk in shorts watching Old Faithful erupt while six miles away, a cold front drops an inch of snow on Dunraven Pass. The park sits at an average elevation of 8,000 feet, and that altitude does not care what month the calendar says.
The range is genuinely absurd. Summer daytime highs can exceed 70°F (21°C), only to drop 20 or more degrees when a thunderstorm rolls through. Winter lows frequently drop below 0°F (-18°C), especially at night. The official forecast for "Yellowstone" is almost useless because the park covers nearly 3,500 square miles - conditions at the West Entrance near West Yellowstone can be completely different from what's happening at the Northeast Entrance near Cooke City.
I'll walk you through each month's conditions, what you can actually do, and the details the forecasts skip. Whether you're hiking in July or watching wolves in January, timing matters more here than in almost any other park in the lower 48.
Month by Month
January
Temperature range: Highs around 20°F (-7°C), lows near -10°F (-23°C). Often colder. What's open: Only the North Entrance near Gardiner, Montana, stays open to regular vehicles. The road from Gardiner through Mammoth Hot Springs to Cooke City remains plowed. Everything else requires oversnow vehicles - snowmobiles or snowcoaches. What's happening: This is deep winter. Snowpack exceeds 100 inches in some areas. The park averages 150 inches of snow annually, and January is peak accumulation. Expect frozen waterfalls, steaming thermal features contrasting against snow, and some of the best wolf viewing of the year. The Lamar Valley becomes a winter wildlife corridor. Crowd level: Very low. You will share the park with a few hundred other visitors, not the tens of thousands of summer. The catch: Daylight is short. Sunrise around 7:45 AM, sunset before 5:30 PM. Roads between Gardiner and Cooke City can close temporarily during storms. Cell service drops out at the park boundary - plan accordingly.February
Nearly identical to January. Slightly more daylight. Slightly less brutal cold by the end of the month. The oversnow season continues through March 15 for most roads. If you want Yellowstone without crowds, this is it. Bring a parka rated for -20°F and expect to layer aggressively.
March
Temperature range: Highs 30-40°F (-1 to 4°C), lows 10-20°F (-12 to -7°C). Transition month. Oversnow vehicles run through March 15 on most routes. After that, the park enters a weird limbo where many interior roads are closed entirely - no cars, no snowmobiles - while crews clear snow. The plowing process takes about six weeks and involves moving snow that's 10-15 feet deep in some stretches.The West Entrance reopens to regular vehicles on the third Friday in April in a normal year. But March? You're limited to the North Entrance road and whatever sections have been plowed. Wildlife activity picks up as bison and elk move to lower elevations.
April
Temperature range: Highs 40-50°F (4-10°C), lows 20-30°F (-7 to -1°C).The most unpredictable month. The park could get a foot of snow or 60-degree sunshine. Probably both in the same week. Road plowing continues, and the West Entrance typically reopens mid-month. The East and South Entrances stay closed until May.
Mud season. Lower-elevation trails become slippery, boot-sucking muck. Higher trails stay buried. This is the least popular time to visit for good reason: limited access, limited activities, and weather that can't make up its mind.
What makes April worth it: Solitude. If you can handle the uncertainty, you might have sections of the park entirely to yourself. The North Entrance road stays open, and Mammoth Hot Springs is accessible year-round.May
Temperature range: Highs 50-65°F (10-18°C), lows 30-40°F (-1 to 4°C).The park wakes up. All entrances open by mid-May in most years. The East Entrance opens the first Friday in May, the South Entrance the second Friday. Most interior roads follow shortly after.
Snow is still possible. Common. Expect at least one storm that drops 3-6 inches somewhere in the park. But the lower elevations - Mammoth, Gardiner, the Lamar Valley - start showing green. Wildflower season begins at low elevations around mid-May.
Wildlife highlight: Grizzly bears emerge from dens in March and April, and May is prime time for seeing them in the Lamar Valley and Hayden Valley. Bison calves appear. Elk calves follow in late May. Trail conditions: Anything above 7,500 feet is still snow-covered. Lower trails are muddy. Bring waterproof boots and expect to posthole through snowbanks if you try higher routes.June
Temperature range: Highs 60-75°F (15-24°C), lows 35-45°F (2-7°C).The sweet spot for many visitors. Snow is possible but uncommon at lower elevations. Most park roads are fully open by early June. The Beartooth Highway (US 212) from the Northeast Entrance typically opens late May to mid-June, weather depending.
Trail conditions: Rapidly improving. Snow lingers on north-facing slopes and above 8,000 feet, but the main hiking Yellowstone national park trails become passable. The Yellowstone Lake Overlook Trail and Storm Point Trail are usually clear by mid-June. Crowd level: Moderate and increasing. June sees about 800,000 visitors - busy but not July/August insane. What the park website doesn't mention: The mosquitoes. June is peak mosquito season in Yellowstone, especially around marshes, lakes, and slow-moving rivers. Bring repellent. The insects are aggressive enough to ruin an evening at a campsite.July
Temperature range: Highs 70-85°F (21-29°C), lows 40-50°F (4-10°C).Peak summer. Also peak crowds. July is the busiest month in Yellowstone, with over a million visitors. Expect traffic jams near Old Faithful, the Grand Canyon of the Yellowstone, and anywhere bison are visible from the road.
The afternoon thunderstorm reality: Almost every July day follows the same pattern. Clear morning. Clouds build by noon. Thunderstorms roll through between 2 PM and 5 PM. Lightning is real - the park sees about 25,000 cloud-to-ground strikes annually. If you're above treeline when thunder starts, you are in a dangerous position. Plan hikes to finish by early afternoon. Wildlife highlight: Elk are common in meadows. Bison are everywhere. Wolf viewing in Lamar Valley remains good in early morning. Pronghorn antelope on the northern range. Trail conditions: All trails are snow-free except a few high-elevation routes. The park's 900+ miles of trails are fully accessible. Wildflowers peak at high elevations - alpine meadows explode with color in late July.August
Nearly identical to July. Slightly cooler by the end of the month. Crowds remain at peak levels through mid-August, then begin a gradual decline. The same afternoon thunderstorm pattern holds.
What's different: Smoke from wildfires becomes a possibility. Yellowstone has had major fire seasons - 1988 burned 793,000 acres - and even moderate fire years bring hazy skies. Check air quality forecasts before booking. Some years are fine. Some years the smoke settles into the Yellowstone Caldera and doesn't clear for weeks.September
Temperature range: Highs 55-70°F (13-21°C), lows 30-40°F (-1 to 4°C).The best month for hiking. Crowds drop significantly after Labor Day. The afternoon thunderstorm pattern weakens. Temperatures are comfortable. Mosquitoes disappear. Trail conditions remain excellent through most of the month.
Fall color: Aspens and cottonwoods turn gold in mid-to-late September. The northern range and Lamar Valley show the best color. The timing varies by elevation - higher areas turn first. Wildlife highlight: Elk rut. September is when bull elk gather harems and bugle - an unforgettable sound echoing through the Lamar Valley and Mammoth area. Bring binoculars. Keep your distance. Bulls are aggressive during rut. Snow returns: Late September can bring the first significant snowfall of the season, especially at higher elevations. Dunraven Pass and the Beartooth Highway may close temporarily. By early October, winter starts reasserting itself.October
Temperature range: Highs 40-55°F (4-13°C), lows 20-30°F (-7 to -1°C).Shoulder season. Most park services begin shutting down. The East, South, and West Entrances close to regular vehicles in early November. Many Yellowstone national park lodges close by mid-October. The campgrounds at higher elevations close for the season.
What makes October worth it: Solitude. Fall color lingers in lower elevations. Wildlife viewing remains excellent. You might see your first significant snow accumulation of the season. The elk rut continues into early October. What's challenging: Limited services. Many facilities are closed. Weather is highly variable - you could get 60-degree sunshine or a blizzard. Bring everything.November
Temperature range: Highs 30-40°F (-1 to 4°C), lows 10-20°F (-12 to -7°C).The park goes quiet. Most entrances close to regular vehicles by early November. The North Entrance remains open, and the road from Gardiner to Cooke City stays plowed. Everything else becomes accessible only by oversnow vehicles starting December 15.
Snow season begins in earnest. The park averages 50+ inches in November at higher elevations. Winter sports enthusiasts start arriving. Cross-country skiing and snowshoeing are possible on unplowed roads.December
Temperature range: Highs 20-30°F (-7 to -1°C), lows 0-10°F (-18 to -12°C).Winter operations begin December 15. Snowmobiles and snowcoaches start running on interior roads. The park enters its quietest period - a few thousand visitors per month instead of a million.
What's open: North Entrance year-round. Oversnow access to Old Faithful, Canyon, and other interior areas. The Old Faithful Snow Lodge is one of the few lodges open in winter. Wildlife highlight: Wolves. December through February is the best time for wolf watching in the Lamar Valley. Bison are visible along the Gardner River and in the Madison area.
Best Times for Specific Activities
Hiking the high country
July through mid-September. The high-elevation trails - anything above 8,500 feet - don't clear until July in most years. September offers the best combination of snow-free trails, comfortable temperatures, and fewer people. By late September, snow can return to the high country.Wildlife viewing
Wolves: December through February in Lamar Valley. Early morning, before the snowcoaches arrive. Grizzly bears: May and June in Lamar Valley and Hayden Valley. Dawn and dusk. Bison: Year-round, but the largest herds concentrate in Hayden Valley and Lamar Valley during summer. Winter bison gather near thermal areas and the Gardner River. Elk: September for the rut. May and June for calves. Year-round in the northern range. Birds: May and June for songbirds. September and October for migrating waterfowl.Wildflower peak
Low elevations: mid-May through June. High elevations: late July through early August. The alpine tundra of Mount Washburn and Dunraven Pass puts on a show in late July that rivals any garden.
Fall color
Mid-September through early October. The northern range and Lamar Valley have the best aspen displays. The drive from Mammoth to Tower-Roosevelt is particularly good.
Stargazing
Year-round, but summer offers the most comfortable conditions. September through April has the darkest skies due to fewer visitors and less light pollution. The park is an International Dark Sky Park. The Milky Way is visible on moonless nights from almost anywhere away from the developed areas.
Winter sports
December 15 through March 15 for oversnow vehicle access. Cross-country skiing and snowshoeing are possible on unplowed roads from November through April. The park has no downhill ski areas - this is backcountry touring only. The groomed trails near Mammoth and Old Faithful are popular for classic cross-country skiing.
What to Pack by Season
Summer (June-August)
The temperature swing is the thing. You will experience 70°F at midday and 40°F by evening, with potential rain, hail, or graupel in between.
Pack: A warm jacket (fleece or light puffy), rain gear (jacket and pants - ponchos are useless in wind), hiking boots with good tread, sun hat, sunscreen, sunglasses, insect repellent, and a headlamp. That last one seems odd for summer, but if you get caught out after sunset on a hike, you will need it. What first-timers miss: The UV intensity at 8,000 feet is significantly higher than at sea level. Sunburn happens fast, even on overcast days. And the afternoon thunderstorm reality means your rain jacket should live on top of your pack, not buried at the bottom.Fall (September-October)
Layers are everything. Mornings can be below freezing. Afternoons can hit 70°F early in September.
Pack: Base layer (merino wool or synthetic), insulating mid-layer, windproof outer shell, warm hat, gloves, waterproof boots. By October, add a heavy winter coat and hand warmers.Winter (November-April)
This is serious cold. Not "I'll just wear an extra sweater" cold. Hypothermia-in-minutes-if-you-get-wet cold.
Pack: Heavy parka rated for -20°F, insulated pants or snow pants, wool base layers, multiple pairs of gloves (one lightweight for dexterity, one heavy for warmth), insulated waterproof boots rated for at least -20°F, balaclava or face mask, goggles for snowmobile travel, hand and foot warmers. Do not underestimate winter conditions. People die in Yellowstone winters from exposure.Spring (April-May)
The mud season demands waterproof everything. Waterproof boots with gaiters. Rain pants. Quick-drying pants, not jeans - wet denim at 40°F is miserable and dangerous. Warm layers for morning, lighter layers for afternoon, and a shell for the inevitable rain or snow.
What the Forecast Doesn't Tell You
1. The "partly cloudy" forecast at Mammoth means nothing at Old Faithful.The park is large enough that weather systems move through differently in different sections. Check the forecast for the specific area you'll be in, not the generic "Yellowstone" forecast.
2. The afternoon thunderstorm pattern is predictable but ignored by most visitors.Every clear summer morning, visitors start long hikes at 10 AM without considering where they'll be at 2 PM. Rangers will tell you the number of lightning-related rescues each year is higher than it should be. Start early. Be below treeline by early afternoon. It's that simple.
3. Snow can close roads in June.Not common, but it happens. In 2022, Dunraven Pass didn't open until June 10. In 2023, the Beartooth Highway opened May 26. Plan flexibility into your itinerary. If you're booking Yellowstone national park camping reservations for early June, have a backup plan for road closures.
4. The temperature drops 3-5°F for every 1,000 feet of elevation gain.The West Entrance sits at 6,700 feet. Dunraven Pass tops out at 8,859 feet. That's a 10-15°F difference, minimum. A comfortable 70°F at the entrance can be a windy 55°F at the pass, with snow flurries.
5. Wind is a bigger comfort factor than temperature in many areas.The Lamar Valley and Hayden Valley are wind tunnels. A 35°F day with 20 mph wind feels like 20°F. The exposed areas around Yellowstone Lake are particularly brutal. Wind chill matters more here than in most parks.
6. Thermal area weather is its own microclimate.Standing near a large hot spring or geyser basin, you'll feel the humidity spike. Your glasses fog. Your clothes feel damp. Then you walk 50 feet away and it's dry and cold. The temperature fluctuation around thermal features is disorienting and can make layering decisions tricky.
7. The "best" weather window is narrower than you think.For optimal conditions - snow-free trails, comfortable temperatures, minimal crowds, no smoke, no mosquitoes - you're looking at roughly September 1 through September 20. That's it. Three weeks. Everything else involves compromise.
Practical Takeaways
- If you want to hike high-elevation trails, come between July 1 and September 15. Anything earlier risks snow. Anything later risks snow returning.
- If wildlife is your priority, come in September for elk rut or December-February for wolves. Summer wildlife viewing is good but diluted by crowds.
- If you hate crowds, avoid July and August entirely. September, October, May, and June offer far better experiences with far fewer people.
- Pack for 40°F temperature swings year-round. The person who shows up in August with only shorts and t-shirts will be cold. The person who shows up in May with only a heavy parka will overheat.
- Check road status before you arrive, not during. The park website updates road conditions daily. As of 2026, the Gardner River High Bridge has traffic delays with up to 15-minute waits - plan extra time.
- The North Entrance is your year-round lifeline. If you're visiting in winter or early spring, this is your only vehicle access point. The town of Gardiner, Montana, has services year-round.
- Buy an America the Beautiful pass if you're visiting more than one park. The standard Yellowstone national park entrance fee for a private vehicle is $35 for seven days. The annual pass costs $80 and covers all federal recreation lands. Do the math.
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For more information, see our complete National Park Guide. Related: Yellowstone national park lodges guide Related: Yellowstone national park hotels guide