San Diego is bracing for a winter of weather extremes as a powerful El Niño pattern takes hold in the Pacific, with forecasters warning the region could see anything from destructive flash floods to punishing surf and eroding beaches — or, just as easily, a disappointingly dry season with heightened wildfire danger.
El Niño occurs when surface waters warm across the central and eastern tropical Pacific, weakening or even reversing the trade winds that typically blow from the Americas toward Asia. That shift sends warm water sliding eastward, fueling rising air and storm activity. Historically, the pattern has meant wetter winters for Southern California, and this year’s version is shaping up to be an intense one.
“Big El Niño events tend to tilt the odds toward more winter storms hitting the North Pacific, and bigger storms too, because of the energy the ocean pumps into the atmosphere,” said Dan Cayan, a researcher at the Scripps Institution of Oceanography.
Scientists classify an El Niño when sea surface temperatures rise half a degree Celsius above normal, according to Tyler Rodenbaugh, chief meteorologist for the San Diego County Water Authority. When temperatures climb 1.5 degrees above normal, forecasters call it a “very strong” El Niño — which is exactly what’s developing now.
Past strong El Niño winters have brought San Diego prolonged, heavy rain. During 1982-83, the region logged 70 rainy days, compared with the usual 40 to 45 — roughly one and a half times the normal number of storm days, Cayan said. The same pattern repeated in 1997-98. Both winters dumped nearly 20 inches of rain at Lindbergh Field, far above the typical 10-inch average, and also boosted Sierra Nevada snowpack, driving heavier statewide runoff.
But the so-called “Godzilla El Niño” of 2015-16 broke that trend, delivering a relatively dry winter with just 8 inches of rain recorded at the airport.
“What actually happens depends on specific storms called atmospheric rivers, which aren’t governed by El Niño itself,” said Alexander Gershunov, a research meteorologist at Scripps. Atmospheric rivers are long, narrow bands of moisture-rich air — essentially rivers in the sky — that can unleash torrential rain regardless of the broader ocean pattern.
Built at the base of hillsides, atop flood plains and threaded with canyons, San Diego’s geography makes it especially vulnerable to flooding. How much damage actually occurs often comes down to the condition of the infrastructure meant to hold the water back.
The devastating January 2024 flooding along Chollas Creek, which damaged roughly 1,000 homes in the Shelltown neighborhood, remains a stark example. Fire officials have described it as a once-in-a-thousand-year event that was largely unavoidable, with Cayan noting the creek drains a small watershed vulnerable to sudden, intense downpours.
But many residents argue the damage was worsened by years of neglected maintenance. Thousands of flood survivors have filed lawsuits claiming the city failed to properly maintain its storm drain channels, and many say they continue to suffer health problems — including skin rashes, respiratory issues and swelling — that they attribute to floodwater exposure or the mold that later took hold in their homes.
The city’s current budget cites more than $800 million already spent on stormwater system upgrades, including 18 completed projects last year, but also lists $3.3 billion in additional needed improvements without a clear funding plan. City officials say crews are working to keep the drainage system as functional as possible, clearing channels and debris so water can flow freely during storms. Fire-Rescue Deputy Chief Robert Rezende, who is overseeing the city’s El Niño preparedness effort, said crews are also coordinating with the San Diego Lifeguard Service’s swift-water rescue team to clear brush, open floodgates and remove obstructions to ensure emergency access if people become trapped.
San Diego County is taking similar steps, monitoring conditions and dispatching field crews to clean storm drains and culverts, trim trees and sweep roads in unincorporated areas, according to county spokesperson Donna Durckel.
In North County, Rep. Mike Levin announced a $26 million federal grant to repair the levee system along the San Luis Rey River near Oceanside and clear sediment from the channel — improvements to a flood-prone waterway that had been promised since 1970 but never carried out.
Pollution remains another persistent concern. Residents of southern San Diego and neighboring Imperial Beach regularly contend with sewage and industrial runoff flowing north from the Tijuana River. During heavy rain, that flow can overwhelm treatment plants, sending more untreated waste into the river and out to the ocean, creating hazardous beach conditions.
Flood control efforts are further complicated by the age of San Diego’s dams, which average about 100 years old — among the oldest in the nation. Four dams have safety issues requiring repair, including one at Lake Hodges rated “unsatisfactory” with an “extremely high downstream hazard potential” by the state Division of Safety of Dams.
That dam needs full replacement, but a plan to rebuild it by 2029 collapsed after cost estimates jumped from $275 million to as much as $697 million. The county water authority had agreed to cover half the replacement cost but backed out once the price more than doubled.
City officials are pressing forward regardless. In 2024, the City Council approved a 10-year, $100 million management contract for San Diego’s Dam Safety Program and expanded its dam safety team, which handles inspections and maintenance. The city is currently designing 36 short-term repair projects, according to spokesperson Jennifer McBride, though officials estimate $3 billion will be needed over the coming decades to complete all necessary upgrades.
In the meantime, the state has ordered San Diego to keep Lake Hodges below 280 feet to reduce the risk of dam failure during flooding. Some residents worry the lower water level is harming wildlife habitat, while reduced water storage could also raise wildfire risk — a real concern given that El Niño winters can swing toward drought just as easily as deluge.
Then there’s the surf. Big waves are already on forecasters’ radar, delighting surfers while worrying coastal officials. These swells build as sea levels rise from warmer water expansion, low-pressure systems, shifting ocean circulation patterns, and the layering of higher sea levels atop unusually high tides.
Gershunov warned that oversized waves can devastate coastal infrastructure, pointing to the 1982-83 El Niño, when the historic Scripps Pier suffered irreparable damage and the landmark Marine Room restaurant flooded. “There was a lot of coastal damage because big waves coincided with astronomically high tides,” he said. “The risk of coastal damage and erosion is elevated again this winter.”
Still, he noted a silver lining: “I think surfers who love big waves should be pretty happy this winter.”
Original source: CalMatters
