The portion of California considered to be in moderate drought continues to expand

Drought conditions in California continued to expand, according to the most recent U.S. Drought Monitor data released Thursday.

After what experts are calling California’s driest February on record, slightly more than 34% of the state was deemed to be in moderate drought. That’s an increase of about 11% over figures released a week ago.

Moderate drought expanded south from San Francisco to include San Mateo and Alameda counties. Drought areas in Butte, Glenn and Tehama counties spread west to encompass Mendocino County, most of Trinity County and southeastern Humboldt County, as well as southwestern Shasta County. To the north near the Oregon border, moderate drought areas in Siskiyou County expanded westward into Del Norte County.

Farther south, drought areas expanded to include more of Kern County, all of Kings County and a little more of western Fresno County.

Almost 70% of the state is either in moderate drought or abnormally dry. Monterey County on the Central Coast is a drought-free island in this area, and southeastern Inyo County and all of San Bernardino, Orange, Riverside, San Diego and Imperial counties are currently excluded from the abnormally dry or moderate drought territory.

(Paul Duginski / Los Angeles Times)

As of Thursday, the Northern Sierra 8-Station Index is at 49% of average for the date, according to the California Department of Water Resources. The index is the average of eight precipitation measuring sites that provide a representative sample of the Northern Sierra’s major watersheds. These watersheds include the Sacramento, Feather, Yuba and American rivers, which flow into some of California’s biggest reservoirs, providing a large portion of the state’s water supply.

A trough from the Pacific is expected to bring moderate snow to the Sierra Nevada on Saturday, according to the National Weather Service. Snow levels will come down to 4,500 feet with 4 to 8 inches expected above that elevation. The heaviest snow will fall during the day on Saturday, possibly making chain controls necessary.

Southern California is expecting cooler temperatures with a chance of light showers this weekend. More significant rain is possible Monday through Wednesday.