Recent swells dare Santa Barbara surfers to test the waters. LAURYN CUMMINS / DAILY NEXUS

If you were anywhere on the California coast last month, you were likely one of millions receiving high surf warnings and coastal flooding advisories. On Dec. 28, 2023, Santa Barbara experienced 20-foot waves that had weakened from 40-footers after a few hundred miles of traveling to the shore. Despite the warnings, many surfers took to spots like Rincon Beach Park and caught double overhead waves, meaning the waves scaled about 12 feet. 

In Ventura, an unexpected rogue wave sent eight onlookers near the shore to the hospital and caused significant damage and flooding in the streets. The wave that rushed in without warning is known as a “sneaker wave.” And, according to Tim DeVries, a professor in the Department of Geography at UC Santa Barbara, sneaker waves are typically at least twice as big as average waves and can come unexpectedly if one is not watching the water.

“On any given day, waves come into the coast in many different sizes,” DeVries said. “During a large swell, the average size of the waves might be 10 feet, but occasionally there may be 15-foot, 18-foot or even 20-foot waves.”

DeVries warned potential beachgoers to be on guard. 

“One should always expect them to come at some point,” he said. “The best way to identify sneaker waves is to look at the ocean and watch the waves — do not turn your back on the ocean!” 

Ventura County spent $2 million in the aftermath to repair the Ventura Pier and coastline damage. Many other coastal communities such as those in San Luis Obispo County and Santa Cruz closed their beaches and piers in light of the high surf.  

So, what is causing these huge wave events? Dave Gomberg, a meteorologist at the National Weather Service, explains that the waves were generated by two cyclones in the Pacific spanning from Alaska to the Central Coast. Despite being hundreds of miles away, these powerful storms produced 40-foot waves that dropped to 20-footers as they reached the coast.

In addition to the storms, a King Tide was expected to hit the shore on Jan. 11, increasing concerns for more coastal flooding. A King Tide is an exceptionally high tide, usually the highest of the year, followed by an extremely low tide. According to DeVries, large tidal swings of especially high and then especially low tides are linked to the full moon and the new moon, occurring twice a month. During these events, the Earth, Moon and Sun have aligned gravitational forces.

“When this situation coincides with the Earth, Moon and Sun being closer together than usual, then you get King Tides,” DeVries said. “Now, when you get a very high tide combined with very large waves, then you can get a lot of coastal flooding, which would be an unfortunate coincidence.” 

Although the cyclones in the Pacific have receded, more storms may form during the El Niño season which is expected to continue until April 2024. It is advised to exercise caution in close proximity to the ocean, especially during high surf. Whether you’re heading to Campus Point or Sands Beach, stay vigilant and keep a close eye on the waves!

A version of this article appeared on p. 10 of the Jan 25, 2023 print edition of the Daily Nexus.