A strengthening El Niño is expected to influence weather across the United States this fall and winter, increasing the likelihood of above-average temperatures across much of the country and wetter-than-normal conditions in large portions of the South, according to a seasonal outlook released Thursday by the National Oceanic and Atmospheric Administration's Climate Prediction Center.
Forecasters said El Niño conditions are firmly established and are expected to strengthen through the end of the year. The Climate Prediction Center estimates there is a greater than 90% chance the event will become “very strong” during the fall and winter of 2026-27, and a 75% chance it could rival or exceed some of the strongest El Niño events observed since 1950.
El Niño is a recurring climate pattern characterized by warmer-than-average sea surface temperatures in the tropical Pacific Ocean. The phenomenon can alter atmospheric circulation patterns and influence seasonal temperature and precipitation trends around the globe.
In its three-month outlook for October, November and December, the Climate Prediction Center favored above-normal temperatures across much of the western United States, nearly all areas east of the Mississippi River and much of the northern Plains.
The strongest signal for above-average temperatures was forecast for parts of Southeast Alaska, the northern Great Basin and areas near North Dakota and northwestern Minnesota.
“The coupled ocean-atmosphere system reflected a strengthening El Niño,” forecasters wrote in the outlook discussion.
The agency said sea surface temperatures in parts of the eastern equatorial Pacific exceeded 5.4 degrees Fahrenheit (3 degrees Celsius) above average during the past month. Atmospheric indicators, including changing wind patterns and rainfall distribution across the tropical Pacific, also reflected a strengthening event.
While a strong El Niño often brings distinctive weather patterns to North America, forecasters emphasized that seasonal outlooks describe probabilities rather than guarantees.
With an event of this magnitude, the chances of experiencing impacts consistent with El Niño are larger, but they are not guaranteed.
For precipitation, forecasters projected a broad swath of wetter-than-normal conditions stretching from Southern California across much of the Southwest, parts of the Rockies and Great Plains, the lower Mississippi Valley, the Southeast and portions of the Mid-Atlantic.
The highest odds of above-normal precipitation were forecast along parts of the eastern Gulf Coast and Southeast coast.
The wet signal is expected to intensify during winter. Forecasters said California could see a particularly strong increase in storm activity, with chances of above-normal precipitation reaching 50% to 60% in some coastal areas during the core winter months.
The outlook also indicates the favored wet pattern could extend as far north as central Oregon and perhaps beyond, reflecting the expected strength of the El Niño event.
Across parts of the Southeast, probabilities of wetter-than-normal conditions could reach 70% to 80% during portions of the winter season, particularly in southern Georgia and northern Florida.
Meanwhile, drier-than-normal conditions are favored in parts of the interior Northwest and portions of the Great Lakes region, though forecasters described those signals as relatively modest.
The Climate Prediction Center said the developing event differs from some past strong El Niños because it is occurring alongside a negative phase of the Pacific Decadal Oscillation, a longer-term climate pattern in the North Pacific. That could temper some traditional El Niño effects, particularly along parts of the West Coast.
Forecasters also cited unusual ocean temperature patterns in the Gulf of Alaska that could influence seasonal outcomes in portions of the Pacific Northwest.
Even so, the agency said the overall signal points to a classic strong El Niño pattern this winter, with increased odds of warmth across much of the northern United States and wetter conditions across many southern states.
The Climate Prediction Center expects El Niño to weaken during the spring of 2027 and potentially transition to neutral conditions later in the season.
As that occurs, long-term climate trends are expected to play a larger role in seasonal forecasts, with above-normal temperatures favored across much of the country into next summer.
Forecasters cautioned that seasonal outlooks do not predict specific weather events and should not be used in place of shorter-range forecasts. Individual cold waves, winter storms or dry periods can still occur even in areas where seasonal averages are expected to trend warmer or wetter than normal.
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