La Nina is here: What it means heading into winter
A new global weather pattern is taking shape in the Pacific Ocean, one that will help steer storms and influence temperatures across the United States into next year.
A map showing sea surface temperatures around the world. The blue area west of South America depicts where La Niña conditions were present. (NOAA)
A new global weather pattern is taking shape in the Pacific Ocean, one that will help steer storms and influence temperatures across the United States into next year.
"La Niña conditions emerged in September 2025, as indicated by the expansion of below-average sea surface temperatures across the central and eastern equatorial Pacific Ocean," NOAA's Climate Prediction Center said in a press release on Thursday morning. It is likely to continue into the start of 2026.
What is La Niña?
La Niña is a recurring climate pattern that develops when ocean water near the equator in the central and eastern Pacific becomes cooler than the historical average. It’s the counterpart to El Niño, which occurs when those waters are warmer than average.
While La Niña conditions are present, they need to persist for five consecutive three-month periods for La Niña to be official, according to AccuWeather Senior Meteorologist and Long-Range Expert Paul Pastelok.
These shifts in ocean temperatures can alter the jet stream—the fast-moving river of air that circles the planet—and, in turn, influence global weather patterns. Across the Northern Hemisphere, the effects are most noticeable in winter, shaping where cold air, snow and rain are likely to occur in the United States.
What La Niña means for the winter forecast
AccuWeather’s recently released U.S. winter forecast points to La Niña as one of the key drivers of the upcoming season.
Pastelok said La Niña conditions will likely affect snow, rain and temperature trends nationwide, but he emphasized that this year’s La Niña appears to be weak, which leaves room for other oceanic factors to influence the forecast.
One of those factors is a marine heat wave spanning much of the northern Pacific Ocean, stretching from Japan to the U.S. West Coast.
"These waters off the West Coast and extending farther out are very, very important going into our [winter] forecast this year," Pastelok explained. He added that there have not been many winter seasons in recent decades that have had a similar setup across such a vast area of the ocean.
Meteorological winter begins on Monday, Dec. 1.
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