SAN FRANCISCO (CBS/AP) — Surf is building along much of the California coast and beachgoers are warned of dangerous waves, rip currents and possibly some minor flooding.

The National Weather Service has issued high surf advisories Wednesday for stretches of the entire coastline.

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Waves just to the north and south of San Francisco could hit 20 feet, while sets topping 18 feet are expected along the Central Coast. Waves from 8 feet to 12 feet are predicted from Los Angeles to San Diego.

The cause is a large swell generated by a storm off Northern California.

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Authorities say swimmers should watch the waves before entering the water or ask lifeguards for advice.

Meanwhile Southern California’s winter heat wave continues. Forecasters say temperatures will hit the 80s again in many areas.

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