The National Weather Service has issued a hazard warning for coastal beaches Monday and Tuesday because of long-period swells likely to produce large surf and strong rip currents.
The warning for the central and northern coasts includes Sonoma County and extends into southern Monterey County.
The surf was expected to particularly forceful on Monday, the weather service and U.S. Coast Guard said.
But beach visitors should take extra precautions through Tuesday because of the additional danger of large, forceful waves capable of washing people off their feet, the National Weather Service said.
Long-period swells means there is a longer period of time between waves than usual. But each wave then carries greater energy and force as it reaches shore.
Fishermen should avoid fishing from rocks and jetties, the weather service said.
Beachgoers should always keep their eyes on the ocean.