Federal forecasters said Thursday that El Niño is now almost certain to turn strong, giving it a 97% chance of being strong or very strong over the three-month period ending this December. They also put the odds of a very strong event at 81%, a level that would make this one of the most powerful El Niño weather patterns on record.
The forecast matters because strong El Niños tilt winter odds in California. For Southern California, that usually means a better chance of above-average rainfall, along with a higher risk of flash floods and landslides. The same pattern can also increase the risk of heat waves on land and at sea, giving the coming winter a sharper edge before the first storms even arrive.
El Niño develops when warmer water builds in the central and eastern tropical Pacific Ocean, and Michelle L’Heureux said the signal is already showing its strength. She said a section of ocean waters in June was the fourth-warmest recorded for the month dating back to 1950, and she said the warm pool in the western equatorial Pacific Ocean is expanding farther to the east. Precipitation has already been enhanced over the central and east-central tropical Pacific, a sign that the atmosphere is responding to the shift.
That does not mean every strong El Niño delivers the same result on land. During three of the four very strong events in the global record, downtown Los Angeles got significantly more rain than average, and in 1982-83 and 1997-98 it received more than double its usual yearly rainfall. But 2015-16 showed the limits of the signal: downtown Los Angeles got only half its typical annual rainfall even in a very strong El Niño. A strong event in winter 2023-24 brought well-above average rainfall across coastal Southern California, slightly above-normal precipitation in coastal Northern California and below-normal totals in interior areas like the Sierra Nevada and southeastern state deserts, while downtown Los Angeles saw the second-rainiest three-day period since recordkeeping began in 1877 and Los Angeles County had hundreds of landslides.
For now, the near-term question is not whether El Niño will matter, but how much. The National Oceanic and Atmospheric Administration’s Climate Prediction Center has effectively locked in a strong winter signal, but the amount of rain Southern California actually gets still depends on where the storm track settles. A strong El Niño typically pushes the winter jet stream farther south and can bring more storms to Southern California, yet the difference between a wet season and a damaging one will not be known until December has passed and the storms have had their say.
