The National Weather Service is warning beachgoers of the increased risk of potentially deadly sneaker waves beginning late Friday and lasting into Sunday.
A Beach Hazards Statement was issued Thursday night for coastal Sonoma County to Monterey County, especially on northwest-facing beaches.
Sneaker waves suddenly surge much farther up the beach than expected and can overtake the unaware, according to the weather service. The waves can sweep people into frigid water.
Small waves can wash the beach for 10 to 20 minutes immediately before a sneaker wave strikes, the weather service said.
The weather service advises watching the waves from high ground for 20 minutes before moving close to the water, and never turning your back on the ocean.
Sneaker waves can also dislodge logs and heavy debris along the beach, knocking over or pinning down the unwary.