Mountains & snow — the Sierra, the passes and California's ski areas

The Sierra Nevada is a single tilted fault block: a long, gentle western slope and an abrupt eastern escarpment dropping 10,000 feet into the Owens Valley. Pacific storms arrive from the west and are lifted continuously as they climb the ramp, condensing out moisture the whole way — so by the time an air mass crosses the crest, it has already given up most of what it was carrying.

That geometry is why elevation alone will mislead you about where the snow is. Which side of the crest you are on matters more than how high you are. Blue Canyon sits at 5,300 feet on the western slope and takes about 62 inches of precipitation a year; Bishop sits at 4,150 feet on the far side and takes under five.

And the snowpack is not scenery. It is the state's largest single store of water, releasing through spring at exactly the time of year when nothing is falling from the sky — see Water.

The mountain regions. Gold dots are the ski areas — plotted at their region's centre, not their exact coordinates.

The ski areas, by elevation

BASE TO SUMMIT — THE NUMBER THAT DECIDES SNOW OR RAIN

Each bar runs from an area's base to its summit. It is the most useful single figure about a California ski area, because in a state where the snow level routinely sits between 5,000 and 8,000 feet during a storm, a few hundred feet of base elevation is the difference between a good day and rain in the parking lot.

Elevations as published by the areas themselves. No snowfall averages appear here deliberately — resort-published snowfall figures are marketing numbers rather than measurements, they are not measured the same way between areas, and this site does not carry numbers it cannot source. What California's snowpack is actually judged on is water content, measured by the state's snow courses and pillows.

The transect, west to east

ONE AIR MASS, CROSSING THE RANGE

Ordered by longitude rather than elevation, because the story is crossing the range. Watch the precipitation column climb the western slope and then collapse the moment it passes the crest.

NOAA/NCEI 1991–2020 normals. Most Sierra co-op stations do not publish a snowfall normal — precipitation is shown instead, which is the more meaningful number anyway, since what the snowpack stores is water and not depth.
Place	Elevation ft	Annual precip ″	Jan mean low	Side

What decides a mountain season

Few storms, not steady snow

Sierra snow arrives in a handful of very large events rather than continuously. Four or five atmospheric rivers can make a season; their absence unmakes it. A December that looks quiet is not a slow start, it is a large fraction of the year that will not be recovered.

Snow level is everything

The same storm total arriving warm rains on ground that should be collecting snow. It runs off in days instead of releasing over months, and a resort at 6,300 feet gets rain while one at 7,900 gets three feet. This is why base elevation matters more here than in the Rockies.

Passes close

Donner Pass on I-80 at 7,056 feet, Tejon Pass on I-5 at 4,144, and Tioga at 9,945 — the highest highway pass in the state, shut by snow from roughly November to late May. Chain controls are a routine part of a Sierra winter, not an emergency.

The east side is different

Mammoth sits on the crest rather than behind it, which is why it holds snow and a long season while Bishop, forty minutes down the escarpment, is in a desert. The Eastern Sierra is not a colder version of the west side; it is a different climate.

Southern California has real snow

Big Bear and Wrightwood sit above 6,600 feet in the Transverse Ranges, two hours from beaches that have never seen any. They are also the most rain-vulnerable areas in the state, because their summits are lower than most Sierra bases.

Dust ends it early

Dust deposited on the snowpack darkens it, so it absorbs more sunlight and melts weeks earlier than it otherwise would. Early melt means the water arrives before the demand does, and passes through.

Analysis

FILED UNDER MOUNTAINS & SNOW

Heading into the mountains?

This page explains the climate. It carries no snow depth, no road status and no avalanche forecast, and none of those should be taken from a page that is not updated hourly.

Live snowpack and reservoir data: DWR / CDEC snow surveys. Avalanche forecasts: Sierra Avalanche Center, Eastern Sierra Avalanche Center. Roads and chain controls: Caltrans QuickMap. Forecasts and Winter Storm Warnings: the National Weather Service.