Yellowstone National Park (Yellowstone) weather in May
May in Yellowstone National Park: cold, a little rain, with reliable snow — a great time to visit.
Updated September 2026 · climate normals from ERA5 reanalysis
#5 of 12 months in Yellowstone National Park · #841 of 1413 destinations to visit in May · comfort 78/100 (tier B)
- Days
- 12°C
- Nights
- -4°C
- Wet days
- 12
- Sun
- 12 h
- Humidity
- 73%
- Daylight
- 15 h

Traveller notes on Yellowstone National Park in May
Yellowstone-forum threads on a May visit describe the stretch from the third Friday of April through most of May as genuinely cold, posters calling not all roads and sights open yet during this window. Regulars recommend avoiding anything much earlier than May 20 for a spring trip, real risk of snow on roads and trails before that point. Regulars call lodging inside the park a genuine advantage for anyone touring multiple areas, cutting down drive time between geyser basins and wildlife-viewing stretches. Posters recommend planning a loop that balances lodges rather than backtracking, several forum regulars offering specific route suggestions based on which roads have reopened. Regulars call real layers essential regardless of a sunny afternoon, May mornings here still capable of a hard freeze. The record: 11.5C days feeling like 10C, -4C nights, an extraordinarily high 58.3mm across over 12 days and 58 percent humidity.
Other months in Yellowstone National Park
Yellowstone-forum threads on an April visit describe interior roads as genuinely opening on a staggered basis, posters naming the third Friday of the month as the historical start. Regulars call Mammoth Hotel and Cabins along with Old Faithful Snow Lodge as typically opening around the twenty-fourth, several posters naming this the real point when more lodging becomes available. Posters call the Lamar Valley road between Mammoth and Cooke City the real standout for wildlife, several regulars naming it the best route for wolf viewing alongside bears, bison, bighorn sheep, elk and coyotes. Regulars call the park genuinely not fully open in April, several threads naming closed gates, lodging and visitor centers as real limitations this early. Posters recommend May instead if bear sightings matter most, several regulars calling this the honest tradeoff for visiting in April rather than waiting. The record: 6.6C days, -9.3C nights, 57.4mm across over 11 days and 73 percent humidity.
Yellowstone-forum threads on February describe this as genuinely one of the most scenic months for a winter visit, posters calling the geothermal features dramatically more striking with steam rising against snow and ice. Regulars call most roads closed to regular vehicles this time of year, a snow coach the standard way to reach Old Faithful and Norris Geyser Basin. Regulars describe wildlife as considerably more visible in February, animals pushed into lower valleys like Lamar making sightings genuinely easier than in summer. Posters call this the start of wolf mating season, pack activity and territorial behavior both more observable now. Regulars recommend a proper expedition-grade coat and real layers regardless of how short outdoor stops are, wind chill genuinely severe. Posters call a guided snow coach tour worth the cost for anyone unfamiliar with winter logistics. The record: -2.6C days feeling like -8C, -15.4C nights, 70.5mm across nearly 12 days and 80 percent humidity.
Yellowstone-forum threads on July weather call it the most reliable stretch of the year here, warm, sunny days that regulars still pair with a genuine overnight chill - temperatures can drop right near freezing after dark even as the afternoon runs comfortably warm. Posters describe a fairly common daily arc: a clear, mild morning, a warm midday, an afternoon thunderstorm that can drop hail with little warning, then a cool evening. The standing packing advice across threads is real layers regardless of the forecast - shorts and a t-shirt for the hike, a proper jacket for camp once the sun drops. July is also repeatedly named the best-weather month of the surrounding season, ahead of both June's lingering snowmelt and August's afternoon smoke risk some years. The record: 23.8C days feeling like 21C, 4.1C nights, just 22mm across 5.9 days, 47 percent humidity and 13.5 hours of sun.
August in Yellowstone starts at the hottest the park gets and cools steadily from there - warm days, nights that drop hard, and, regulars are careful to add, snow flurries and freezing nights entirely possible in mid-August. Our row backs them: a 22.3C day against a 4.4C night that feels like 2C, and 0.3cm of snow inside the monthly normal. The crowd shape is the other reason to read the month in halves. The first three weeks are very busy with families; the crowds thin from mid-month as school and college start, and the last week sees roughly 100,000 fewer visitors than July. The wildlife follows the same curve, animals coming back down as the high country cools. The record: 7 precipitation days carrying 37.3mm, humidity 51 percent and 12 hours of sun.
Year-round notes are on Yellowstone National Park's overview. Add your own note from Yellowstone National Park's card on the map.
Yellowstone National Park climate normals — May
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Yellowstone National Park in May
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
BusyMemorial Day weekend(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Yellowstone National Park's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherYellowstone National Park's weather peaks June–August.
Best weatherFair weatherToughest weather
What's on in Yellowstone National Park in May
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Rule
Bear management area closures
10 Mar – 10 Nov · usuallyClosuresParts of the backcountry shut on fixed spring and autumn dates to keep people off carcass sites and berry slopes. The dates are published and do not move for the weather, so check before planning a route. Source ↗
- Opening
Roads reopen to cars
15 Apr – 30 May · usuallyTrail seasonThe road system is ploughed open in phases from the third week of April, with the high passes last in late May. Late April gives you geyser basins with snow on them and almost no traffic. Source ↗
- Nature
Spring wildlife on the northern range
15 Apr – 15 Jun · usuallyWildlife seasonBison calves in the Lamar Valley from late April, bears out of the den on the lower slopes, and wolves visible against the last snow. The best wildlife weeks of the year, before the crowds.
- Opening
Beartooth Highway open
22 May – 12 Oct · usuallyTrail seasonClosuresThe road over the 3,300-metre pass to the northeast gate opens around the end of May and closes in mid-October, earlier if it snows. It is the best drive in the region and the first thing shut. Source ↗
- Holiday
Memorial Day weekend
23–25 MayNational holidayCrowdedBook earlyMemorial Day, the last Monday of May, opens the summer travel season: over the long weekend campsites and lodging book out, roads are slow, and parking at the most popular spots fills early in the day. Source ↗
Nearby, and something's on
Within 300 km of Yellowstone National Park — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Yellowstone National Park?
Yellowstone National Park in May — FAQ
- Is May a good time to visit Yellowstone National Park?
- May in Yellowstone National Park: cold, a little rain, with reliable snow — a great time to visit. It ranks #5 of 12 months for Yellowstone National Park on SeasonMap's comfort score (78/100).
- What is the weather like in Yellowstone National Park in May?
- In May, Yellowstone National Park averages a daily high of 11.5°C and a low of -4°C, with about 58.3 mm of rain over roughly 12.3 rainy days.
- What is the air quality in Yellowstone National Park in May?
- Yellowstone National Park has a mean US Air Quality Index of about 58 in May.
- Does it snow in Yellowstone National Park in May?
- Yellowstone National Park sees roughly 25.6 cm of snowfall in May.
Within 300 km: Big Sky's Yellowstone roads open around 15 Apr – 5 Nov, and Grand Teton National Park's Memorial Day weekend on 23–25 May.