Yellowstone National Park, a vast high-altitude plateau with an average elevation of approximately 8,000 feet, experiences significant snowfall throughout the year. Its continental climate, far from the moderating influence of oceans, ensures that cold temperatures and winter precipitation are the norm for many months. Snow is a major factor shaping the ecosystem, dictating visitor access, and defining the park’s seasons.
The Seasonal Timeline of Snowfall
The main period of heavy snow generally spans from November through April, when the majority of the park’s roads are closed to wheeled vehicles. Snow accumulation typically begins in mid-to-late October, with the winter season lasting nearly eight months. December is often the month with the highest average snowfall, with certain measuring stations recording an average of 13.0 inches of new snow. The shoulder seasons, May and October, feature unpredictable conditions where a snowstorm is common. Even during the summer months of June, July, and August, snow is possible, especially at the park’s higher elevations.
Geographic Differences in Accumulation
Snow accumulation is not uniform across the park, showing significant variation based on elevation and local topography. The highest plateaus and mountain ranges receive substantially more snow than the lower-elevation valleys. Annual snowfall averages around 150 inches across much of the park, but certain areas at higher elevations can record between 200 and 400 inches.
Regional Variation
This difference is clearly seen when comparing the park’s north and west sides. The North Entrance area near Gardiner, Montana, sits at a lower elevation and receives the least annual precipitation, sometimes as little as 11 inches. Conversely, the higher Yellowstone Plateau and western mountain slopes experience a strong orographic effect, dropping large amounts of moisture as snow. The Pitchstone Plateau, for instance, can receive total annual precipitation exceeding 70 inches, primarily due to winter snowfall.
Navigating the Park During Snow Conditions
The park’s interior roads close to regular private vehicles in early November and remain closed until late April or early May. From mid-December through mid-March, most of the park is only accessible via commercially guided snowmobiles or snowcoaches during the “over-the-snow” season. Only the road connecting the North Entrance at Gardiner, Montana, to the Northeast Entrance at Cooke City, Montana, remains open to private automobiles year-round, weather permitting.
Winter Driving and Access
Visitors driving during the spring or fall shoulder seasons must be prepared for winter conditions. Park regulations often advise or require winter-rated tires on vehicles, particularly when roads are icy or snow-covered. While the park service clears roads quickly, temporary closures can occur, and carrying chains is strongly advised for safety. Accessing main features like Old Faithful during deep winter requires booking a guided tour.