LOS ANGELES — Exceptionally high tides are set to hit California as early as this weekend, sending officials scrambling to prepare for another onslaught along the state's already battered coast.

The National Weather Service issued a coastal flood warning that goes into effect Sunday morning and lasts through Thursday afternoon, saying it expects "significant coastal flooding" in San Diego and Orange counties that will inundate low-lying homes, businesses and critical infrastructure, with some shoreline erosion in the morning throughout the warning period.

Significant-to-moderate beach erosion is likely in Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, and "isolated damage of structures due to sea water inundation is possible," forecasters said. A coastal flood advisory has been issued over the same time period in those four counties.

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

In the San Francisco Bay and Monterey Bay areas, forecasters warned of up to 1.9 feet of inundation above ground level near shorelines and tidal waterways, with rising tides bringing waves farther up the beach than normal, "restricting escape from beaches and coastal areas." A coastal flood advisory for those areas goes into effect Saturday morning and lasts through Thursday afternoon.

The shoreline has already been hammered by an unprecedented confluence of threats this year: the arrival of El Niño off the coast of Peru, which has fueled an unusually active hurricane season in the eastern Pacific Ocean; a longstanding and unrelated marine heat wave that has broiled the shoreline for months, and a particular alignment of the Earth, sun and moon seen only once every two decades.

And the threats may only intensify. Tides are expected to get even higher around Thanksgiving, Christmas and Martin Luther King Jr. Day. The coast could be particularly hammered if the exceptionally high king tides coincide with strong winter storms.

"It's likely to get worse before it gets better," said Daniel Swain, a UC Agriculture and Natural Resources climate scientist.

Tides could break modern-day records in San Diego and Orange counties in the coming days, the National Weather Service said. When adjusted for how record-hot the ocean has been off the coast, tides could reach 7.5 to 8 feet, or even higher, above baseline, which is defined as the average low-water level observed between 1983 and 2001. (Hotter water raises the sea level, as water expands as it heats up.)

Water at the surface at Scripps Pier in La Jolla, a neighborhood in San Diego, reached a high point for the year of around 77 degrees, when the average maximum is around 70 degrees. Just on Thursday, the surface temperature there was around 73 degrees, well above the average of 66 for this time of year.

All that is contributing to unheard-of increases in sea levels. The National Weather Service says actual tides in Southern California are running 1.25 to 1.75 feet above what would be expected from just the position of the Earth, sun and moon, given the hotter ocean temperatures.

"As far as I know, this is unprecedented, especially for this length of time," said Reinhard Flick, a researcher at the Scripps Institution of Oceanography at UC San Diego. Water levels have been at least "half a foot above the prediction for months."

Without accounting for the hot ocean temperatures, La Jolla would expect to see a maximum high tide of 6.14 feet on Sunday morning, 6.44 feet on Monday morning, 6.59 feet on Tuesday morning, 6.55 feet on Wednesday morning and 6.3 feet on Thursday morning, according to federal government predictions published years ahead of time. Actual tides, however, could push it beyond 8 feet.

The problem partly stems from a long-predicted surge in peak high tides, caused by a particular alignment of the Earth, moon and sun. We're near the peaks of what's known as the 18.6-year lunar node and 4.4-year lunar perigee tidal cycles, which arise from small changes in the orbit of the moon and affect tide-generating forces, according to Flick.

Another problem has been the record-breaking warm waters off the California coast, which are starting to be influenced by an El Niño-fueled dispatch of warmer ocean waters from the Peruvian coastline. Human-caused global warming is also playing a role, with sea levels having risen by about 1 foot over the past 125 years on the California coastline.

The coastal flooding in the next few days is expected to be different from earlier rounds, which were heavily influenced by powerful swells from the remnants of hurricanes Marie and Rachel. Those tropical storm-influenced swells won't be present, but the tides will be higher this time.

Such conditions will especially put at risk areas that have already been socked by rising seawater — like the Long Beach Peninsula, where the ocean tore up a historic boardwalk and walloped homes; and Newport Beach's Balboa Peninsula, which saw days of intense flooding.

"I think it will be on a similar scale," said Philip Gonsalves, a meteorologist with the National Weather Service office in San Diego. "You're going to have different contributing factors producing a similar outcome."

Other areas that have been hit hard this year include Dana Point, where waves damaged beachfront homes, destroyed decks and tore through walls; and Malibu, where a sinkhole is threatening actor Nicolas Cage's home, and where the ocean has threatened to cut off vehicular road access to Point Dume Beach, known by locals as Westward Beach.

In San Diego County, parts of Carlsbad State Beach have washed away, forcing the closure of the Tamarack day-use parking lot to vehicles. So much sand has eroded at the popular Newport Beach surfing spot The Wedge that remnants of decades-old buried infrastructure, like rusted metal rods and chunks of concrete, have been exposed.

Areas that have already suffered beach erosion or infrastructure damage may be especially vulnerable. Any additional flooding "exacerbates the issue because the damage is already there," said Todd Hall, warning coordination meteorologist for the weather service office in Oxnard.

One area of concern is on Highway 1 in Ventura County near Point Mugu, where water got underneath the roadway and weakened it, which "makes it more susceptible to additional tidal events," Hall said. Crews are installing boulders to separate the roadway from the waves.

What is clear is that officials and the public shouldn't be surprised about coastal flooding this week.

"The warning and advisories are real. People should take them seriously because conditions are favorable for flooding," said Doug George, an oceanographer with the National Oceanic and Atmospheric Administration.

Newport Beach has declared a local emergency ahead of the tides and activated its emergency operations center, gearing up for flood prevention and response efforts. The city was also "reinforcing protective sand berms, preparing pumps and tide valves and positioning resources in flood-prone areas," officials said on social media.

The city said the highest tides it expects are 8.3 feet on Monday at 9:15 a.m., 8.5 feet on Tuesday at 9:50 a.m., and 8.4 feet on Wednesday at 10:28 a.m. Those adjusted figures are 1.8 feet higher than the predictions that don't take into account hotter ocean water.

Both Newport Beach and Long Beach are also rushing to move sand to shore up eroded beaches.

Newport Beach said about 30 to 40 trucks have been moving sand from an area above Prado Dam to The Wedge, with the goal of moving 2,000 cubic yards by Saturday. Crews have also been installing thousands of sandbags in vulnerable parts of Balboa Island, the city said.

In response to a crack developing beneath Coast Highway, or Highway 1, which connects Newport Beach to Laguna Beach, the California Department of Transportation said it is placing 4-foot-tall, sand-filled barriers beneath the roadway near Crystal Cove. The two lanes closest to the cliff remain closed, with traffic routed on the remaining two lanes, with one lane in each direction.

"The barriers will provide interim protection to the slope by helping to absorb wave energy. The next step will involve installing a fill buttress at the base of the slope, reinforced with large rocks to help reduce erosion and limit further slope movement," Caltrans said on social media.

Long Beach on Tuesday began dredging Alamitos Bay and is moving sand to the beach on the wave-battered Peninsula, using, essentially, a giant hose. The effort has "already added visible beachfront to the area adjacent to the 72nd Place parking lot," on the eastern edge of the Peninsula, city spokesperson Jen De Prez said. Repairs have also begun on the Peninsula's damaged boardwalk.

Metrolink has announced it is suspending commuter train service in southern Orange County and San Diego County for the coming workweek, due to the tide forecast.

In the Bay Area, crews this weekend are shutting down a section of an entire state highway for 55 hours for emergency work to prepare for winter. The ultimate goal is to raise, by 3 feet, parts of flood-prone Highway 37, which connects Marin and Sonoma counties to Napa and Solano counties.

El Niño is a climate pattern characterized by warmer waters in the central and eastern tropical Pacific Ocean that spur changes in the atmosphere that can affect weather around the world. El Niños are typically associated with coastal erosion in California and more stormy weather than usual in the southern United States, including Southern California.

©2026 Los Angeles Times. Visit latimes.com. Distributed by Tribune Content Agency, LLC.