Coastal flood warnings issued as exceptionally high tides threaten California beaches

The National Weather Service announced a coastal flood warning for San Diego and Orange counties beginning Sunday morning and lasting through Thursday afternoon, forecasting significant flooding of low-lying homes, businesses and infrastructure. A coastal flood advisory was also issued for Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, where forecasters expect significant to moderate beach erosion and possible isolated damage to structures.

In the San Francisco Bay and Monterey Bay areas, officials warned of up to 1.9 feet of inundation above ground level near shorelines and tidal waterways, with higher tides pushing waves farther up the beach and limiting escape routes. A coastal flood advisory for those regions runs from Saturday morning through Thursday afternoon.

The high tides are attributed to a combination of astronomical factors—peaks in the 18.6-year lunar node and 4.4-year lunar perigee cycles—and unusually warm ocean temperatures that raise sea level. Adjusted forecasts suggest tides could reach 7.5 to 8 feet above baseline in Southern California, exceeding predictions that do not account for water temperature.

Local authorities are taking precautionary measures. Newport Beach declared a local emergency, activated its emergency operations center, reinforced sand berms, prepared pumps and tide valves, and began moving sand to vulnerable beaches. The city expects peak tides of 8.3 to 8.5 feet early next week. Long Beach is dredging Alamitos Bay and relocating sand to the Peninsula to restore beachfront area.

Transportation agencies are responding as well. Caltrans is installing sand-filled barriers beneath Highway 1 near Crystal Cove to protect the slope, while Metrolink has suspended commuter service in southern Orange County and San Diego County for the workweek. In the Bay Area, a section of Highway 37 will be closed for 55 hours to raise flood-prone segments by three feet.

"Take the necessary actions to protect flood-prone property," the weather service advised.

"The warning and advisories are real. People should take them seriously because conditions are favorable for flooding," said NOAA oceanographer Doug George.

"You’re going to have different contributing factors producing a similar outcome," said National Weather Service meteorologist Philip Gonsalves.

Experts noted that the combination of high tides and potential winter storms could exacerbate flooding later in the season, including around Thanksgiving and the winter holidays.