California Coast Put on Alert for 'Tremendous' Waves That Could Reach Up to 40 Feet

Waves of up to 40 feet (12 meters) high could hit California’s coastline on Thursday. The treacherous surf marks the first swell of winter weather for the Golden State.

The US state of California is preparing for massive waves this week as Pacific storms have been churning up the surf along the coastline from Eureka to Santa Cruz with monstrous waves.

Waves ranging in height between 10 and 20 feet—with some as high as 25 feet—are forecasted to hit parts of central and Southern California, with officials warning peak figures for "tremendous wave energy" would likely be documented throughout Thursday.

Significant beach erosion is likely as well as flooding, and some waves could even be strong enough to damage piers. High surf warnings and advisories were put into effect for the state’s coastline in preparation for the storm.

Evacuations were ordered across California as the storm began. The Bay Area, Calles Pinos, Pradero, Sierra, Onda Resaca, Ribera, and parts of Calle Del Arroyo, Embarcedero all issued evacuation warnings on Thursday.

The first huge swell of the winter has arrived in California, and with it comes dangerous surf set to rival some of the biggest waves this year.

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— San Francisco Chronicle (@sfchronicle) December 28, 2023

“People are advised to stay out of and well away from the water, and keep a close eye on kids and pets,” the National Weather Service for the Bay Area wrote on Wednesday. “These are deadly conditions that can easily overpower the strongest swimmers.”

“We really want to hammer home that beaches will be very dangerous,” added Nicole Sarment, a weather service meteorologist. “People should really not even go.”

This is the first time that the Bay Area National Weather Service has issued a high surf warning since January, when a storm destroyed Santa Cruz’s scenic West Cliff Drive. This week, multiple storms have whipped up the Pacific Ocean over the course of several days, with a series of hurricane-force winds helping to create the threatening swell.

A coastal Flood Warning is in effect for southern California until 3 pm! Beware of potential flooding, high tides, and strong winds along the coast due to large waves. Stay safe! #CoastalFloodWarning #CAwx pic.twitter.com/gt1rbANJ5c

— WeatherNation (@WeatherNation) December 28, 2023

At least three factors help to create these dramatic wave heights: wind speed, fetch, and time.

Fetch being the area over the ocean where winds blow and generate waves, says the weather service. The longer the weather system sits there, the higher the waves will be. These type of weather systems are also more common during the winter months.

High tides, big waves and rip currents are on tap for Southern California #beaches for the next couple of days. This is the view from the pier in #HermosaBeach. @knxnews pic.twitter.com/cLgKuXdUZv

— Jon Baird (@KNXBaird) December 28, 2023

“As those (swells) come to the coast and they break, that’s when you get those large waves at the coastlines and at the beaches,” said Alexis Clouser, a weather service meteorologist. “These are not the highest wave heights we’ve seen, but they’re certainly on the larger side."

Waves as high as 42 feet were seen in the open ocean far offshore on Wednesday, Clouser explained. “They are deadly due to their size and the potential run-up — our biggest concern is people getting too close to the water and potentially getting swept in.”