The National Weather Service is advising of high surf expected on exposed west- and northwest-facing shorelines of San Luis Obispo, Santa Barbara, Orange and San Diego counties.
Forecasters say the surf will build to 10 to 12 feet through Friday afternoon and overnight, then subside to below 10 feet Saturday morning.
The advisory says ocean activities will be potentially dangerous for anyone, with hazards including rip currents and localized beach erosion.
The advisory is set to expire at 10 a.m. Saturday, an hour after the morning's approximately 6-foot high tide.
Copyright NBC San Diego / Associated Press