--- title: "A very strong El Nino is forming and San Diego is spending on levees and dams" description: "Federal forecasters put the odds that El Nino lasts into early spring 2027 at 97 percent, and the odds it reaches very strong this fall at 81 percent. What that means for how much rain actually falls on Southern California is a much weaker signal than most people assume, and San Diego is spending accordingly: on levees, dams and storm channels that pay off whether the winter is wet or not." category: "California" category_url: https://herald.la/category/california author: "Lucía Fuentes" published: 2026-08-01T13:52:19.000Z updated: 2026-08-01T13:52:19.000Z canonical: https://herald.la/article/a-very-strong-el-nino-is-forming-and-san-diego-is-spending-on-levees-and-dams tags: ["el-nino", "weather", "flooding", "san-diego", "infrastructure", "climate"] --- # A very strong El Nino is forming and San Diego is spending on levees and dams Federal forecasters put the odds that El Nino lasts into early spring 2027 at 97 percent, and the odds it reaches very strong this fall at 81 percent. What that means for how much rain actually falls on Southern California is a much weaker signal than most people assume, and San Diego is spending accordingly: on levees, dams and storm channels that pay off whether the winter is wet or not. The ocean part of this is not in much doubt. [NOAA's Climate Prediction Center](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml), in its July 9 discussion, put the chance that El Nino persists through early spring 2027 at 97 percent, and the chance of a very strong El Nino during October through December at 81 percent. Sea surface temperatures in the tropical Pacific are already running about 1.5 degrees Celsius above normal, [CalMatters reported](https://calmatters.org/environment/2026/08/el-nino-san-diego-winter-weather/). The atmosphere part is where the confidence drops, and it is worth being precise about why. ## What El Nino does and does not tell you A warm Pacific loads the atmosphere with energy and moisture, which tends to produce more North Pacific storms and bigger ones. "Large El Ninos tend to tilt the odds toward more winter north Pacific storms and also larger ones, because of the energy imparted to the atmosphere from the ocean," Dan Cayan of the Scripps Institution of Oceanography told CalMatters. Tilting the odds is not the same as forecasting rain. Whether Southern California gets soaked depends on atmospheric rivers, the narrow moisture corridors that deliver most of the state's big rain, and on exactly where they come ashore and how long they stall. Alexander Gershunov, also at Scripps, put it bluntly: those storms "do not dance to the tune of El Nino." CalMatters reported that the link between tropical ocean conditions and Southern California rainfall has weakened this century. The record at San Diego's Lindbergh Field makes the point better than any explanation. A normal year brings about 10 inches. The 1982-83 and 1997-98 El Ninos, both among the strongest measured, each brought roughly 20 inches, with 70 wet days in 1982-83 against a normal 40 to 45. The 2015-16 event, nicknamed the Godzilla El Nino and forecast to be enormous, delivered 8 inches. That is below a normal year, in one of the strongest El Ninos on record. ## What San Diego is buying The county's spending is structured to be worth it either way, which is the sensible response to a probabilistic forecast. CalMatters reported that San Diego has already spent $800 million on stormwater improvements and estimates it needs $3.3 billion more. A $26 million federal grant is going to repair the San Luis Rey River levee system near Oceanside. A $100 million, 10-year dam safety management contract was signed in 2024, with roughly $3 billion in dam repairs anticipated over the coming decades. The Lake Hodges dam replacement shows the scale of the problem: a plan fell through as the estimated cost climbed from $275 million to $697 million. The immediate work is less glamorous and more useful in the next four months: clearing storm channels, removing debris, brush clearing, opening gates. ## The coast, not just the rain The other El Nino signal is stronger than the rainfall one. Warm water expands, raising sea level, and El Nino winters bring bigger waves. When those coincide with high tides, the coast takes damage regardless of how much rain falls inland. That is what happened in 1982-83, when big waves met astronomically high tides: Scripps Pier was damaged beyond repair and the Marine Room restaurant flooded, CalMatters reported. Gershunov expects the risk of coastal damage and erosion to be higher this winter. ## What this reporting does not cover One honest limitation. The CalMatters reporting is about San Diego County. It does not address Los Angeles County, and it does not address the debris flow risk on hillsides burned in recent fires, which is the hazard most likely to matter here when heavy rain does arrive. That risk is real and well understood in principle, but no current warning or LA County preparation is documented in the sources for this story. We are not going to extrapolate San Diego's planning onto Los Angeles on our own authority. What Angelenos can take from this is the forecast itself, which is regional: a very strong El Nino is likely, a wet winter is possible but not assured, and the coast is the part of the signal forecasters are most confident about. ## Sources - [Fierce floods or wild waves? How San Diego is preparing for a winter of extreme weather under El Nino](https://calmatters.org/environment/2026/08/el-nino-san-diego-winter-weather/) - [ENSO Diagnostic Discussion](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)