A Beach Hazards Statement was issued for San Francisco, Coastal North Bay including Point Reyes National Seashore, San Francisco Peninsula Coast and Southern Monterey Bay and Big Sur Coast Counties.
The weather service said northwest-facing beaches are most at risk for sneaker wave threat beginning Monday afternoon as long period northwest swell moves through the coastal waters.
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Large, unexpected waves can sweep across the beach without warning and can move large objects such as logs, it said.
The public is advised to avoid rocks, jetties, and steep beaches and stay much farther back from the water.
According to the weather service, there can be 30 minutes of small waves before a sneaker wave strikes.