An atmospheric phenomenon occurring over much of California was unmistakable in satellite imagery in late autumn 2025. Fog stretching some 400 miles (640 kilometers) across the state's Central Valley appeared day after day for more than two weeks in late November and early December. Known as tule (TOO-lee) fog, named after a sedge that grows in the area's marshes, these low clouds tend to form in the valley in colder months when winds are light and soils are moist.

An atmospheric phenomenon occurring over much of California was unmistakable in satellite imagery in late autumn 2025. Fog stretching some 400 miles (640 kilometers) across the state’s Central Valley appeared day after day for more than two weeks in late November and early December. Known as tule (TOO-lee) fog, named after a sedge that grows in the area’s marshes, these low clouds tend to form in the valley in colder months when winds are light and soils are moist.