Following the recent attention on the “polar vortex” in the past few weeks, federal meteorologists state that the La Niña phenomenon remains the key force influencing the winter weather in the United States this year.
According to the monthly update released on Thursday (December 11) by the National Meteorological Bureau of the National Oceanic and Atmospheric Administration (NOAA), federal scientists from the Climate Prediction Center confirmed that the La Niña phenomenon, which began in October, is expected to continue affecting the winter weather in the United States from 2025 to 2026. Meteorologically, December, January, and February are considered winter months.
The La Niña phenomenon and the polar vortex have been dancing around the Arctic. The polar vortex typically determines how much cold air can move southward, while La Niña guides the direction of this cold air.
As of mid-December, a branch of the polar vortex is preparing to release extremely cold air into the central and eastern United States.
Meteorologists suggest that after this event, the polar vortex may weaken, allowing the more typical La Niña pattern to take over and will likely influence the weather at least until the end of December through January.
La Niña is part of the natural climate cycle known as the El Niño-Southern Oscillation (ENSO). This cycle causes fluctuation in sea surface temperatures in the tropical Pacific Ocean near the equator between warm and cold phases, with La Niña indicated by sea surface temperatures in the region being lower than average by 0.5 degrees Celsius, and El Niño indicated by temperatures higher by 0.5 degrees Celsius. When sea temperatures fall between these two extremes, it is referred to as a “neutral” condition.
La Niña is one of the major factors influencing weather in the United States, especially during late autumn, winter, and early spring.
Climate scientist Michelle L’Heureux from the Climate Prediction Center of the National Meteorological Bureau mentioned in an email to USA TODAY on December 10: “The latest Climate Prediction Center seasonal outlook indicates that the impacts of the precipitation anomalies from La Niña are expected to persist until at least April 2026.”
She pointed out that “La Niña signals correlate with drier conditions in the southern states and wetter conditions in the northern states.”
The influence on snowfall is expected to result in abnormally high snowfall in winter in the northwestern United States, the northern Rockies, the Great Lakes region, and the northeastern inland areas.
Michelle L’Heureux stated, “Currently, we predict a transition to a neutral state of the El Niño-Southern Oscillation around January to March 2026.”
The report from the Climate Prediction Center of the National Meteorological Bureau also noted, “Even as sea surface temperatures in the equatorial Pacific transition to a neutral state, the impacts of La Niña may continue into early spring 2026 in the Northern Hemisphere.”
[This article references USA Today’s reporting.]