San Francisco, Calif. – The West Coast faces an unpredictable winter as neutral ENSO conditions strip away the strong climate signals that usually guide seasonal forecasts. From California to Washington, the 2025-26 season could swing between prolonged dry periods and powerful storm events.
According to the National Weather Service, California, Oregon, and Washington all have “equal chances” for above, below, or near-normal precipitation this year. That uncertainty could bring San Francisco weeks of dry skies only to be followed by an atmospheric river, while Seattle and Portland may toggle between drizzles and strong rainmakers.
Mountain snow is especially hard to pin down. The Cascades in Washington and Oregon, along with California’s Sierra Nevada, are key water sources for the region. In past neutral winters, these ranges have alternated between drought-stricken years and seasons with deep snowpack that boosted reservoirs.
Travelers should also prepare for volatility. I-5 through Oregon and Washington could face snow and ice at higher elevations with little advance notice. In California, I-80 over Donner Pass and Highway 50 into Lake Tahoe may swing from dry pavement to whiteout blizzards within hours.
Forecasters emphasize that short-term drivers like the Madden-Julian Oscillation or Arctic Oscillation will play outsized roles in steering Pacific storms this year. Those patterns can flip every few weeks, making week-to-week forecasts critical.
Residents across Los Angeles, Portland, and Seattle are urged to monitor advisories closely. Flooding, landslides, and mudflows remain concerns if heavy rains return after long dry stretches. The official winter update, due October 16, will refine precipitation and snowpack expectations.
