Large, dangerous waves expected along the California coastline

A long period swell out of the west and northwest could create the potential of waves of 20-30 feet along the California coastline.

As the Golden State deals with a heat wave, a place not to seek relief from the summerlike weather will be beaches where large waves courtesy of a prolonged swell will make swimming dangerous.

Local National Weather Service offices have issued a High Surf Advisory for coastal communities around San Francisco to Big Sur and Monterey.

Forecasters warn waves could approach 30 feet, especially at beaches where the terrain makes the coast susceptible to currents out of the west and northwest.

Northern parts of the state, Oregon and Washington, have seen increased wave activity courtesy of storm systems making their way through the North Pacific.

The NWS says events known as sneaker waves can surge more than 150 feet up the beach and dislodge large objects, including logs.

The debris can strike swimmers and unsuspecting beachgoers, leading to injuries and the threat of drownings.


The remnants of Super Typhoon Bolaven, which passed through the Northern Mariana Islands and well east of Japan, is contributing to the increased swell experienced along the Pacific.

According to meteorologists at the NWS office in Eureka, California, seeing the potential for waves reaching 20-30 feet typically happens during the winter when bomb cyclones or atmospheric river events parade through the ocean.

Forecast models showed swell periods of at least 20 seconds reaching the coastline, which leads to elevated seas and dangerous high surf.

The larger the swell period, the more potential energy exists when waves develop along the coastline.


The increased swell periods can also lead to classic waves that surfers wait year-round for.

Local NWS meteorologists advise everyone not to be fooled by the looks of the ocean and to never turn your back to the waves.

According to NOAA, sneaker waves kill more people along the West Coast than all other weather hazards.

Swell periods are expected to decrease over the weekend, leading to reduced wave heights and calmer seas.