Winter in the United States may be more varied this year compared to last — with colder and snowier conditions likely in the North and the potential for drier weather than is typical in the South and relative warmth in the Southeast, according to the National Oceanic and Atmospheric Administration’s outlook released Thursday morning.

The season is expected to be dominated by a weak La Niña climate pattern. Although the effects from no two La Niña phases are exactly the same, they feature cooler-than-normal water in the equatorial Pacific Ocean. The most recent winter during a La Niña was the 2022-2023 season.

A La Niña watch remains in effect, and the pattern has been somewhat slow to materialize so far. In a flip from last winter’s strong El Niño, NOAA and other forecast agencies still believe a weak La Niña is likely this winter.

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Indeed, a typical La Niña pattern is expected over the course of the three months.

It often features a semi-permanent dip in the jet stream over Canada and the northwest United States and higher pressure off the Southeast coast, which leads to a warmer east and cooler west in many instances.

An active inland storm track is frequent during a La Niña episode, and that may include many storms that are moisture starved given their origin. Given the usual storm track is farther north than normal, it is more removed from oceanic moisture compared to storms in El Niño that originate farther south, but the dynamic nature of La Niña events can counteract other lacking ingredients.

At times during the season, there may be higher risk than normal for severe weather in the Southeast.

There will likely be higher potential for variability in weather patterns than last winter, which featured relative stability across the season.

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Odds of warmer-than-normal conditions are higher from the southern United States to the East Coast. Areas at highest risk for cooler-than-normal conditions are in the Pacific Northwest to the northern Plains.

Northern Alaska is also favored to see warmer-than-normal conditions, with cooler than normal expected in the south of the state.

There’s also an “increased chance of weakened polar vortex this winter,” said Jon Gottschalck, chief of the operational prediction branch for NOAA’s Climate Prediction Center. That can lead to a “greater chance of Arctic air outbreak farther south than last year.”

Precipitation expectations are also fairly standard for La Niña winters. NOAA is favoring below-average precipitation in the southern tier, while portions of the Northwest U.S. and northern Rockies as well as the Great Lakes could see above-average precipitation.

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Much of the Midwest and central Appalachians region remain in drought, so any added winter precipitation could help alleviate those conditions, which NOAA is forecasting.

La Niña winters tend to douse the Pacific Northwest. This could mean the first dry-leaning winter in California over the past several years, although the last La Niña — two winters ago — was notably wet in the state.

For the Northeast megalopolis, La Niña often delivers mixed-bag winter storms, tending to start as frozen and transition to something other with time. This is thanks to a favored inland track until around New England, compared to a more favorable track for Interstate 95 snow lovers just offshore.

While few outlooks have yet been released, AccuWeather also issued theirs on Monday. It highlights similar expectations to NOAA. It also includes specifics on the potential for snow.

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AccuWeather favors above-average snowfall in portions of northern New England, the Great Lakes and westward along the U.S.-Canada border. The Midwest, Mid-Atlantic and a swath from central California through the central Plains is forecast to have below-average snowfall.

Even a mild winter can feature intense shots of cold air. In the era of human-caused climate change, the cold shots can be especially jarring amid the steadily rising background warmth. La Niña winters such as 2008-2009 featured notable midseason cold snaps like the one that targeted Barack Obama’s inauguration with frigid weather in Washington.

At the same time, the last winter to end up below-average for the contiguous United States was 2013-2014, according to the National Centers for Environmental Information. That winter was neither La Niña or El Niño. There have been only four below-average winters for temperatures since 1999-2000.

How a ‘weak’ La Niña could affect seasonal conditions

Forecasters warned during the summer that an emerging La Niña, in combination with record-warm ocean waters, could fuel an intensely active Atlantic hurricane season. La Niña tends to be associated with wind patterns over the Atlantic that promote the development of tropical storms and hurricanes.

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However, La Niña has been slow to develop, which may have contributed to a historically long stretch without a storm in the Atlantic from mid-August to early September. Though since then, there has been a slew of storms in the last month including Hurricane Helene as well as Hurricane Milton, the fifth hurricane to make U.S. landfall this season.

As of Thursday, forecasters at NOAA said there was a 75 percent chance that a La Niña would develop between December and February. If La Niña does develop, it’s likely to be weak, which can open the door for other, less-predictable climate factors to exert more influence on winter weather.

“Weak events don’t have as consistent an impact on global circulation as stronger events do,” said Emily Becker, an atmospheric scientist at the University of Miami. “Other climate and weather patterns can end up contributing more to seasonal impacts, but … it’s currently not possible to predict them months in advance.”

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There’s also more to the season than La Niña, especially when it is weak.

These phenomena include the Arctic Oscillation, a difference in pressure over the Arctic and the middle latitudes, and the Madden-Julian Oscillation, a collection of clouds and storms near the equator that travels around the planet every 30 to 60 days, to consider.

Higher amounts of autumn snow in Siberia can favor a cold, snowy winter in parts of the United States according to research by Judah Cohen, a meteorologist at Atmospheric and Environmental Research. Snow currently covers more of the region than in any October since 2014, although the second half of the month is looking less snowy, so it’s too soon to draw a definitive conclusion, Cohen said.

Becker points to climate change and ocean temperatures, which remain near record-warm levels, as potential wild cards in La Niña’s development and the winter forecast.

“The expected La Niña is occurring in the context of climate change, and the global oceans are much, much warmer than in our recorded history,” said Becker, who has studied the impacts of La Niña and El Niño on winter weather. “How this might affect the growth of La Niña and its impacts on the winter is an open question.”