El Niño winter snowfall forecast map points to above-average rain and snow across much of the Southwest during December 2026 through February 2027. The same setup could boost the Sierra snowpack and help recharge Lake Mead and Lake Powell by next spring.
California gets about 75% of its annual precipitation during the wet season from November through March, and some parts get as much as 90%. That makes the winter track more than a forecast line for the state: the Sierra snowpack supplies about one-third of California’s water.
California and the Sierra Nevada
The Sierra Nevada and the Rockies are likely to see a lot of help from the Pineapple Express, a jet stream that moves moisture from around Hawaii to the West Coast of the U.S. and Canada in winter. When that flow lines up, it can push Pacific moisture farther inland and drop rain and snow across the Southwest, the Four Corners and Rockies.
For California, the practical effect is straightforward. More of the season’s water arrives as snow in the Sierra, where it can be stored and released later rather than falling all at once. That is why the forecast matters most to water users watching the state’s snowpack and not just its immediate storm totals.
Lake Mead and Lake Powell
The same storm pattern could also improve levels at Lake Mead and Lake Powell. Years of diminishing winter snowpack and lowering lake levels in the West form the backdrop for the outlook, and a wetter winter would offer the first real chance in this setup to reverse some of that decline.
El Niño tilts the odds toward a wetter pattern, but it does not decide where the precipitation lands. Pacific storm systems still move from west to east across the West Coast, and the most useful reading of the map is not a guarantee of snow everywhere but a higher chance that the Sierra and nearby basins do better than in a dry winter.
The Weather Channel and ForecastWatch
The Weather Channel was found to be the world’s most accurate forecaster in ForecastWatch’s Global and Regional Weather Forecast Accuracy Overview, 2021-2024. The overview was commissioned by The Weather Company, which adds weight to the seasonal outlook but does not remove the usual uncertainty in how much snow each mountain region will actually receive.
The next test is simple: whether winter storm tracks deliver enough rain and snow to feed the Sierra snowpack and move water into Lake Mead and Lake Powell by next spring. For readers in California and the broader West, the map is less a promise than a bet on where the season’s moisture will land.
