Tule fog is a type of radiation fog and is named after the tule grass that grows along waterways, such as the California Delta and the many rivers across the Central Valley.

"Tule fog in the Central Valley continues to expand northward early this Sunday morning," the National Weather Service's San Francisco office tweeted in issuing the Bay Area advisory.

Satellite view of tule fog over the Central Valley. Charette said Central Valley residents can expect tule fog to begin forming around December or after the season’s first heavy rain.

The NWS Hanford’s office has issued fog advisories nearly every day across the San Joaquin Valley since Nov. 24. Impacted ...

Dense fog in the Central Valley can lead to accidents, and drivers should be aware of the ingredients needed for fog formation, ... Tule fog is our local name for radiation fog ...

Satellite view of tule fog over the Central Valley. Charette said Central Valley residents can expect tule fog to begin forming around December or after the season’s first heavy rain.

The thick tule fog in Central California is as reliable as the seasons when it appears. The fog, which can happen between October and February, sometimes blankets the 400-mile region from ...

In the fall and winter, California, and especially the Central Valley, sees a dangerous type of fog: tule fog.