"We've seen several inches in the Novato and Santa Rosa area," National Weather Service forecaster Bob Benjamin said.
Heavy rain is expected in area north of Highway 80, Benjamin said.
The strongest winds will affect areas near the ocean and at elevations above 1,000 feet, the National Weather Service said.
Inland winds are expected to reach 20 mph to 30 mph. Near the ocean, winds are forecasted to be as strong as 45 mph with gusts up to 55 mph.
Driving might be difficult for high profile vehicles, including buses, motor homes, and tractor-trailers.
A wind advisory will remain in effect until 5 p.m. today.
"The heaviest portion will be coming through today," Benjamin said.
The rainstorm that began Friday evening is expected to taper off by Monday.
Affected areas include San Francisco and the Peninsula coast, the North Bay, including Point Reyes National Seashore and mountain regions, the East Bay hills and Diablo Range and the Santa Cruz Mountains.