LOS ANGELES (CBSLA.com) — High surf will pound Southern California’s coastline for a 30-hour stretch starting Monday night, creating dangerous conditions for swimmers, National Weather Service forecasters said.

Surf of between 5 and 7 feet is expected by Monday night, rising to between 7 and 10 feet Tuesday morning and persisting through late Tuesday night, according to the NWS.

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A high surf advisory will be in effect in Los Angeles County from 10 p.m. through 3 p.m. Wednesday morning. A less serious beach hazards statement will be in force in Orange County, where forecasters expect similarly sized waves, with sets up to 12 feet, from late Monday through Tuesday night.

“High surf may cause minor beach erosion on exposed west-facing shores,” an NWS statement said. “The large waves and strong currents will create a risk of ocean drowning. Sneaker waves can suddenly overrun previously dry beaches and jetties. Minor flooding of low-lying beach parking lots, harbor walkways, and campgrounds will be possible.”

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The NWS urged beachgoers to always swim near lifeguards and, if caught in a rip current, to swim parallel to shore until free of it

In Los Angeles County, the biggest surf is expected on west-facing beaches, from Palos Verdes to Santa Monica, and from Point Dume to Zuma Beach, the statement said. The risk of coastal flooding will be highest at high tide, which is forecast to be around six feet at 10 a.m. Tuesday.

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In Orange County, the highest surf will be north of Newport Beach, according to the NWS, which said Seal Beach and Sunset Beach could experience minor coastal flooding.

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