The snow line in the U.S. varies dramatically by region, ranging from as low as about 2,300 feet in the Washington Cascades to over 8,200 feet in the Colorado Rockies. There is no single line drawn across the country. Instead, the snow line shifts with latitude, proximity to moisture sources, and which side of a mountain range you’re standing on.
What “Snow Line” Actually Means
The snow line is the elevation above which snow remains on the ground consistently, either year-round (a permanent snow line) or through a given season. In most of the lower 48 states, you’re dealing with a seasonal snow line, meaning the lowest elevation where snow accumulates and persists through winter and into spring. True permanent snow lines, where snow never fully melts, exist only on the highest peaks and glaciers in places like Alaska, the Cascades, and parts of the Rockies and Sierra Nevada.
A useful way researchers measure this is by finding the elevation where at least 50% of the ground is snow-covered on average during early April, which captures the tail end of winter accumulation before spring melt kicks in.
Snow Line Elevations Across the West
The western U.S. is where the snow line is most clearly defined, because the mountain ranges are tall enough and cold enough to hold snow for months. A clear northwest-to-southeast gradient exists: the snow line is lowest in the Pacific Northwest and highest in the southern Rockies. Here’s what that looks like in early April, broken out by the west-facing and east-facing slopes of each range:
- Washington Cascades: roughly 2,300 feet on the west slope, 3,300 feet on the east slope
- Montana Rockies: roughly 3,000 feet on the west slope, 4,600 feet on the east slope
- Sierra Nevada: roughly 5,200 feet on the west slope, 7,500 feet on the east slope
- Colorado Rockies: roughly 8,200 feet on both slopes
The Washington Cascades have the lowest and longest-lasting snow cover of these regions, thanks to a combination of cold temperatures and heavy precipitation rolling in from the Pacific. Colorado’s Rockies, despite their height, receive less winter moisture than the Pacific ranges, which pushes the snow line much higher. You need to get above 8,000 feet in Colorado before snow reliably sticks around through the season.
The difference between west-facing and east-facing slopes matters more than many people realize. In the Sierra Nevada, for example, the snow line on the drier eastern side sits nearly 2,300 feet higher than on the moisture-rich western side. West-facing slopes catch storms first, so they accumulate more snow at lower elevations. The east side, sitting in a rain shadow, stays drier and needs more altitude to keep snow from melting.
How Latitude Shapes the Snow Line
Across North America, snow line elevations follow a predictable pattern tied to latitude. Below about 35 to 40 degrees north (roughly the latitude of Albuquerque or Denver), snow lines are relatively consistent between continents at the same latitude, sitting at higher elevations because temperatures are warmer. Above 40 degrees north, snow lines drop sharply, falling below roughly 4,900 feet. North America, with its enormous high-latitude land mass, has some of the lowest average snow lines of any continent at these northern latitudes.
This is why a place like northern Montana can hold snow at 3,000 feet while southern Colorado needs 8,200 feet. Every degree of latitude you move north effectively lowers the elevation at which snow can persist, because average temperatures drop and the sun angle decreases.
The Eastern U.S. and Appalachians
East of the Rockies, the snow line becomes much harder to pin down because the mountains are lower and the climate is more variable. The Appalachian range tops out below 6,700 feet (Mount Mitchell in North Carolina), and the White Mountains of New Hampshire peak around 6,300 feet. These summits do hold seasonal snow, but the pattern is less consistent than in the West.
In the Northeast, snow cover at lower elevations depends heavily on latitude and storm tracks rather than a clean elevation threshold. Northern Maine and the Adirondacks can hold snow at valley floors (under 1,500 feet) for months, while the southern Appalachians may only see persistent snow above 4,000 to 5,000 feet during colder winters. The concept of a fixed snow line is less useful in the East because moisture comes from multiple directions and temperatures fluctuate more than in the consistently cold, high-altitude West.
Alaska’s Snow Line
Alaska is in a category of its own. With glaciers stretching from the Brooks Range in the north to the coastal mountains of the southeast, permanent snow lines exist at far lower elevations than anywhere in the lower 48. In southeastern Alaska, where maritime moisture is abundant, glaciers descend nearly to sea level. In the interior and northern ranges, permanent snow and ice persist at moderate elevations, though the Brooks Range glaciers tend to be small with limited mass turnover due to extremely short ablation seasons.
The Alaska Range, home to Denali, carries permanent snow and ice well below its 20,310-foot summit. Glaciers in this region maintain snow year-round at elevations that would be completely bare in Colorado or even the Sierra Nevada, purely because of how far north they sit.
Why the Snow Line Keeps Shifting
The snow line is not a fixed boundary. It moves up and down through the year, dropping during winter storms and rising as temperatures warm in spring. In practical terms, someone planning a hike, a drive over a mountain pass, or a ski trip cares about the transient snow line: the current elevation where rain turns to snow or where snow is accumulating on the ground. This can change by thousands of feet within a single storm system.
Over longer periods, the seasonal snow line reflects the balance between how much snow falls and how fast it melts. The spring snow line, measured in early April, captures the moment right before rapid melt begins and gives the best snapshot of where snow has persisted through winter. The tree line on a mountain is closely linked to this snow line. Research shows that the elevation of spring snow cover and the number of days snow stays on the ground are the strongest predictors of where trees stop growing on a mountainside, outweighing even temperature and precipitation alone.
Climate trends are pushing snow lines higher across the West. As average temperatures rise, the elevation at which snow reliably persists through winter climbs, which has cascading effects on water supply, wildfire risk, and ecosystems that depend on snowmelt.