This year’s potentially record-breaking El Niño event is expected to impact winter weather and snowfall across the United States. A new CNN weather analysis shows how snowfall has changed during an El Niño winter and provides clues about what to expect this season.
El Niño is a natural climate pattern characterized by unusually warm ocean waters in the central and eastern tropical Pacific Ocean. That extra warmth changes precipitation and atmospheric circulation patterns, affecting weather far beyond the Pacific Ocean.
El Niño’s impact on U.S. weather is strongest in the winter, when the jet stream (a high-velocity air stream that helps guide storms) typically moves south and spreads east across North America. This change favors a humid climate across the United States, while many northern regions tend to be drier and have milder temperatures.
However, a rainy winter does not necessarily mean a lot of snow. Snowstorms require sufficient cold air, so if temperatures are too high for snow to fall, increased precipitation simply means more rain.
To understand the impact of El Niño, CNN Weather analyzed snowfall from January to March from 1959 to 2026. The map below shows how past El Niño winters have varied from average after adjusting for long-term changes in snowfall. Rather than predicting snowfall this winter, they explain historical relationships.
During past El Niño winters, snowfall was generally above average across the southern United States, extending from parts of the Southwest and southern Rockies to the southern Plains, southern Appalachians, and mid-Atlantic.
Storms that affect snowfall potential in the mid-Atlantic region typically take a course along the spine of the Appalachian Mountains or push off the coast, becoming a nor’easter.
These Northeastern regions are “impacted” by El Niño, said John Gottshalck, director of operational forecasting at NOAA’s Climate Prediction Center and the agency’s lead forecaster for this year’s winter outlook. “They’re very strong and energetic and very wet,” Gottschalk said.
This could bring above-average snowfall to areas such as Washington, D.C. and Baltimore.
While the Northeast typically doesn’t get snow during winters with strong El Niño events, it only takes one major storm to skew the snowpack for the entire season.
Parts of the Pacific Northwest, the northern Rocky Mountains, the Great Lakes, and the interior Northeast saw less snow. Changes in the storm’s path could reduce the chance of snow in some parts of the north, and warmer temperatures could increase the chance of the storm bringing rain.
However, keep in mind that this is relative to the average for each location and is not a measure of which location will get the most snow. Therefore, in the South, where snowfall is typically low, total snowfall on the ground may be small, even with much above average snowfall.
This year’s El Niño is expected to be one of the strongest on record. Gottschalk said that as El Niño strengthens, its typical effects become more likely.
However, compared to a weaker event, it does not necessarily result in a large increase in rain or snow in a particular location. Gottschalk also pointed out that there are relatively few strong El Niño events in the historical record from which firm conclusions can be drawn.
Averages alone can be misleading. A few exceptionally snowy winters could push the total up, even if many other winters are below.
To see where snowy El Niño winters were more common, CNN Weather also looked at how often those years ended with above-average snowfall.
More than half of the El Niño winters analyzed resulted in above-average snowfall in parts of the Southwest, lower Midwest, southern Appalachians, and interior Northeast. Much of the Pacific Northwest, the northern Rocky Mountains, and parts of the Great Lakes experienced below-normal snowfall.
And in moderate to strong El Niños, such as this year’s Super El Niño, the difference is even greater. Areas that typically experience above-average snowfall during El Niño events tend to snow more frequently during strong El Niño events, and areas that typically experience less snowfall tend to snow even less frequently.
The variation in city totals in individual El Niño winters indicates that El Niño is only a rough guide to snowfall in individual winters.
From December through February, NOAA forecasts warmer-than-average temperatures across much of the northern and eastern United States.
Gottschalk said the Pacific jet stream would “flood North America with Pacific air.” Calder ocean air will make it harder for long-term outbreaks to persist in the Arctic, but short-term cold waves remain a possibility.
One wild card is how atmospheric circulation patterns in the Arctic and North Atlantic evolve. This regional shift could spread cold air across the eastern United States and change the path of the storm, even during a strong El Niño event.
Gottschalk said a continuation of the favorable cold pattern could disrupt what was expected to be a mild winter across the North. But forecasters cannot predict with certainty when those symptoms will occur in October or how long they will last.
The timing of the arrival of cold air will become clearer as we get closer to individual storms, he said. Even in a generally mild winter, a short period of cold that coincides with a strong coastal storm can make a big difference in seasonal snowfall.
During the extremely strong El Niño event of 2015-2016, New York City experienced one of the warmest winters on record, according to the National Weather Service. Still, the January 2016 snowstorm dumped 27.5 inches of snow in Central Park, setting the city’s single-storm snowfall record.
