Large marine heatwave persists off the U.S. West Coast since summer 2025

A large marine heatwave has persisted along the U.S. West Coast since summer 2025, raising sea surface temperatures about 1.7–2.2°C (3–4°F) above average across parts of the Northeast Pacific. In a report published March 3, 2026, the National Oceanic and Atmospheric Administration (NOAA) Fisheries said this is only the third time in the observational record for the California Current ecosystem that such a large portion of coastal waters has remained anomalously warm for so long into winter without El Niño conditions. Source