Record ocean temperatures drive unprecedented coastal flooding in Southern California
Unusually warm Pacific waters linked to a strong El Niño have caused sea levels to rise to record heights, flooding streets and businesses along the Southern California coast.
High tide on Monday pushed seawater into business districts in Newport Beach and flooded a section of Pacific Coast Highway in Sunset Beach, while San Pedro recorded a sea-level peak of 8.02 feet, the highest on record. Scientists attribute the surge to unusually warm ocean temperatures that expand water volume, a phenomenon amplified by the current El Niño.
“The waters along the immediate coast of California are actually at record warm levels for the time of year, all the way from about the Farallon Islands south to Baja California,” said UC Agricultural and Natural Resources climate scientist Daniel Swain.
Swain added that the thermal expansion “is comparable to, or even greater than, what we’ve ever seen before of the seawater,” and that it combines direct El Niño effects with long-term ocean warming. NASA climate scientist Josh Willis described the event as an “El Niño Macho,” warning it could match or exceed the 1997 episode that caused extensive global damage.
Sea-surface temperatures off Southern California have risen more than 9 °F above average, with Scripps Institution of Oceanography researcher Reinhard Flick noting a measurement of 73.8 °F at La Jolla Pier, well above the typical 64.7 °F for the date. The elevated temperatures have intensified a Kelvin wave that transports warm water from the equatorial Pacific toward the coast, further raising sea levels.
National Weather Service meteorologist David Gomberg explained that the 8.02-foot reading at Los Angeles Harbor was 1.42 feet higher than astronomical tides alone would predict, a surplus caused by thermal expansion and the Kelvin wave. Residents in Long Beach and Newport Beach reported knee-deep flooding, and local officials are reinforcing sandbags and pumping water to protect vulnerable infrastructure.
Experts caution that the region is approaching the peak of the 18.6-year lunar node and 4.4-year lunar perigee tidal cycles, which could produce even higher tides around upcoming holidays. Combined with any future storms, the risk of severe coastal flooding is expected to increase throughout the winter season.