What could La Niña mean for hurricanes and winter?
A La Niña watch has been issued, but what does that really mean for the rest of Atlantic hurricane season and snow this winter in the U.S.?
El Niño and La Niña are some of the main drivers of a long-range seasonal forecast. AccuWeather's lead long-range expert Paul Pastelok explains.
A La Niña Watch has been issued by NOAA's Climate Prediction Center. But what does that mean for your weather?
La Niña develops when sea surface temperatures in the eastern Pacific Ocean remain cooler than average for an extended time. Its influence on weather in the United States is strongest in winter, shaping storm tracks and temperature patterns, but it also plays a major role in fueling tropical development during Atlantic hurricane season.
A La Niña Watch means that La Niña conditions are expected the next six months. While there will be some La Niña conditions from late autumn through midwinter, a La Niña is only officially declared after five consecutive months of negative sea surface temperatures.
La Niña vs. the U.S. Winter forecast
La Niña is only one of a handful of atmospheric factors that AccuWeather's Long-Range team uses to predict the upcoming winter weather.
AccuWeather Lead Long-Range Expert Paul Pastelok says, "La Niña conditions can set in during this fall through midwinter time period, but the signal will be weak, and other signals could be more dominant than the typical outcome."
La Niña typically alters the jet stream in ways that shape very different winters across North America. In the Northwest and western Canada, two storm tracks often converge, leading to colder-than-average temperatures and above-normal precipitation, AccuWeather Lead Long-Range Forecaster Paul Pastelok explained. Farther east, the northern branch of the jet stream tends to carry faster-moving, less intense storms, which can mean snowfall near or even below average, with temperatures closer to seasonal norms.
Other factors could spoil La Niña effects
Another factor could spoil typical La Niña winter effects in the U.S. This season, a massive marine heat wave stretches from Asia to the West coast of the U.S. and could impact the normal storm track from La Niña, bringing different results, Pastelok explained. "This could possibly result in more snow and cold farther east over the Plains, Midwest and occasionally in the Northeast."
Ocean temperatures compared to historic average over the Pacific Ocean, showing a massive marine heat wave (orange) at the top of the image and the beginning of possible La Niña conditions in the lower right (dark blue).
Exactly who ends up with more or less snow than average will come down to the fine details. AccuWeather will break down those factors — and the regional impacts — when our 2025-2026 U.S. Winter Forecast is released on Oct. 2.
La Niña vs. the end of the Atlantic hurricane season
"The chances of La Niña conditions greatly increase late in the 2025 Atlantic hurricane season, especially in October and November," AccuWeather Lead Hurricane Expert Alex DaSilva said. "This favors an active end to the hurricane season."
When a La Niña phase occurs, less wind shear occurs in the regions of the Atlantic basin where tropical weather develops, increasing the potential for more storms.
The two pie charts show the probability of different ENSO conditions during the middle and late portions of the hurricane season. This forecast shows a near 70% chance of neutral conditions and a near 30% chance of La Niña conditions during the most active part of the hurricane season.
