Huge swells at Mavericks on Jan. 18, 2018
Waves at Mavericks topped 50 feet Thursday. "It’s almost one of those days where you could die just trying to get out," surfers told SFGATE.1 in 5 waves could top 55 feet along Northern California according to National Weather Service.
 
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Waves at Mavericks topped 50 feet Thursday. "It’s almost one of those days where you could die just trying to get out," surfers told SFGATE.1 in 5 waves could top 55 feet along Northern California according to National Weather Service.
Media: Brian Feulner, Special to SFGATE
The NWS warning advises the public to watch out for strong rip currents, beach erosion and large waves that unexpectedly run higher up the beach than is usual.
Beachgoers should keep an eye on kids and pets and never turn their backs to the ocean.
"This will probably be our biggest swell of the season so far," said Brian Garcia with the National Weather Service in Monterey. "It could be the biggest swell of our season."Sets of 22-to-24-foot waves were observed at the Bodega Bay and Point Reyes buoys in the North Bay on Thursday morning at about 8 a.m., and the National Weather Service says breakers up to 32 feet high were possible on the beaches Thursday morning.
West- and northwest-facing beaches between Monterey and Sonoma counties could see some isolated waves with faces up to 40 feet high later in the afternoon. Ocean Beach in San Francisco is among those places where exceptionally large waves could break.
At some off-shore locations, such as Mavericks in Half Moon Bay and Pigeon Point near Pescadero, one in 100 breakers could approach 55 feet, according to the NWS.
Forecasters for the Mavericks Challenge surf contest are watching the swell closely as they try to decide on the ideal day for the big-wave event.
The window for the conest runs until March 31 and surfers are notified up to 72 hours in advance to give them time to travel.
"It's a trifecta for them," said Brian Garcia, a forecaster with the National Weather Service in Monterey. "They have to have the large swell, the right winds and good visibility."
  • Anthony Tashnik rides a wave in heat number one in the first round of the Titans of Mavericks competition in Half Moon Bay , Calif., on Friday, February 12, 2016. Photo: Carlos Avila Gonzalez, The Chronicle
Photo: Carlos Avila Gonzalez, The Chronicle
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Ken Collins, left, and Chris Bertish surf a giant wave during the second heat of the Mavericks surfing contest Friday, Feb. 12, 2016, in Half Moon Bay, Calif. (AP Photo/Ben Margot)
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Anthony Tashnik rides a wave in heat number one in the first round of the Titans of Mavericks competition in Half Moon Bay , Calif., on Friday, February 12, 2016.
Odd Persson, 21 years old from Capetown, came out to the Bay Area four days ago trying to get onto 40-to-50-foot waves at Mavericks. He said conditions are less than ideal.

"Terrible," Persson said. "Too much whitewater. No channel and the rip is so strong. I couldn't get out."
Big-wave surfer Jamie Williams was checking out the surf from the shore at Mavericks on Thursday morning.
"It's almost one of those days where you could die just trying to get out," Williams says.
After not being able to get through the whitewater to get out, Williams was picked up by a Jet Ski to get brought out to the lineup but after getting bucked off twice he turned back.