In pictures: Kiwi waves slam California coast

Hundreds of spectators have been gathering to watch surfers brave 15-foot swells at The Wedge, a break in Newport Beach, California, known for its powerful surf. But these waves are not standard for this area. They are the product of a major storm churning thousands of miles away off the coast of New Zealand.

The epic surf has been slamming beaches in Southern California since Sunday, and lifeguards have been busy watching over the surfers and boogie boarders who have flocked to the area.

In Newport Beach, lifeguards reported 15-foot waves on Monday afternoon. Over the weekend, they rescued 17 people from the dangerous conditions.

Two males walking with pieces of a broken surfboard

Government weather officials have issued a high-surf advisory that will remain in effect until at least the late evening on Tuesday. The advisory, issued by the National Weather Service, warns that some waves may continue to reach 15-feet in height. It also warns of powerful rip currents, which could pull swimmers out to sea, may be present.

Over the weekend, about 55,000 visitors visited Newport Beach, but those numbers dwindled on Monday. Still, officials have dispatched extra lifeguards to the beach because of the large waves.

Lifeguards and meteorologists are warning those braving the surf about the possibility of so-called sneaker waves - large waves that can appear with little or no warning.

Stuart Seto, a weather specialist with the National Weather Service in nearby Oxnard, California, said south-facing beaches in the state experience storm-triggered swells about a dozen times a year - usually in the summer and fall.

"They're very destructive to coastal beaches because they carry away a lot of sand," he said.