The Coast Guard is urging boaters and swimmers to stay away from the waters off the California coast this weekend when swells of up to 19 feet are expected.

Large breaking waves approaching 20 feet and dangerous rip currents are also forecast between 10 p.m. Friday and 10 a.m. Sunday. The National Weather Service has issued a hazardous seas warning and a high surf advisory.

The Coast Guard says people should avoid going near beaches or other low-lying coastal areas, where large waves can sweep even a strong swimmer away. If boaters must be on the water, the agency says they should make sure their safety equipment is in good condition and tell someone on land where they are going and when they plan to return.

Condition are expected to improve by late Sunday night.