Why is a summit forecast different from the town forecast?

Air cools with height, by about 3.6°F per 1,000 feet on average, and wind over a ridge blows at the speed of the free atmosphere. A summit page gives the wind, temperature and freezing level at the summit's own height from the GFS model, next to the National Weather Service forecast at the peak's coordinates.

What is the freezing level?

The height where the air temperature is 32°F (0°C). Above it precipitation falls as snow and wet rock freezes.

Mountain forecasts

631 summits in 30 states

A forecast for the summit, not the valley: the National Weather Service’s forecast at each peak’s own coordinates, the wind, temperature and freezing level at the summit’s height from the GFS model, wind chill, the cloud base against the summit, snow, and sunrise and sunset.

By state Live map with slope angles

The summits on the map

Every summit with a forecast page, Alaska’s and Hawaii’s off the frame. Select one.

Summit

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The highest

Summit	State	Elevation	Prominence
Denali	Alaska	20,308 ft	20,194 ft
Mount Saint Elias	Alaska	18,015 ft	11,312 ft
Mount Foraker	Alaska	17,402 ft	7,201 ft
Mount Bona	Alaska	16,358 ft	6,772 ft
Mount Blackburn	Alaska	16,352 ft	11,591 ft
Mount Sanford	Alaska	16,237 ft	7,638 ft
Mount Vancouver	Alaska	15,787 ft	8,832 ft
Mount Churchill	Alaska	15,564 ft	1,188 ft
Mount Fairweather	Alaska	15,325 ft	12,979 ft
Mount Hubbard	Alaska	14,951 ft	8,061 ft
Mount Bear	Alaska	14,829 ft	5,056 ft
Mount Hunter	Alaska	14,573 ft	4,623 ft
Mount Whitney	California	14,505 ft	10,082 ft
Mount Alverstone	Alaska	14,501 ft	1,903 ft
University Peak	Alaska	14,469 ft	3,209 ft
Aello Peak	Alaska	14,442 ft	1,444 ft
Mount Elbert	Colorado	14,439 ft	9,072 ft
Mount Harvard	Colorado	14,426 ft
Mount Massive	Colorado	14,419 ft	1,982 ft
Mount Williamson	California	14,403 ft
Mount Rainier	Washington	14,400 ft	13,222 ft
Blanca Peak	Colorado	14,350 ft
La Plata Peak	Colorado	14,334 ft
Uncompahgre Peak	Colorado	14,308 ft	4,242 ft
Crestone Peak	Colorado	14,295 ft

What this means

Why a summit forecast differs: The air cools with height, by about 3.6°F per 1,000 feet on average, and the wind above a ridge blows at the speed of the free atmosphere rather than slowed by the valley floor. A town’s forecast says little about the top of the mountain above it.
Freezing level: The height where the air is at 32°F (0°C). Above it precipitation falls as snow and wet rock freezes; the snow line usually sits a few hundred to a thousand feet below it.
Wind chill: How cold the air feels on exposed skin, from the temperature and the wind, by the National Weather Service’s 2001 formula.
Cloud base: Where cloud begins. When it is below the summit, the top is in cloud: no view, and in cold air, rime ice and poor visibility.
Prominence: How far a summit rises above the lowest contour line that encircles it and no higher summit: the measure of a mountain’s own height, not its neighbors’.

Forecasts from the National Weather Service. Summit-height temperature, wind and freezing level from NOAA’s Global Forecast System on NOAA Open Data. Summits from Wikidata (CC0): prominence >= 600 m, or elevation >= 4267 m, or >= 12 Wikipedia editions; English Wikipedia article required; read 2026-09-25. Mountain weather changes fast; check the forecast again before you go.