If La Niña Arrives, How Will It Affect U.S. Winter?

A weak La Niña is predicted to take place this winter, bringing drier and warmer conditions, especially for the eastern United States. There is a 57% chance for the La Niña to emerge in October to December, and continue through January to March 2025, according to a recent report by the Climate Prediction Center. 

Mild winter conditions pose issues for states in the High Plains such as North Dakota, South Dakota, and Nebraska, according to Bret Walts, chief marketing officer and meteorologist for BAM Weather. If the La Niña causes the jet stream to settle further south, the High Plains have a lower chance for snow and may remain in drought going into the spring. 

“It is critical that those areas in the High Plains get a decent snow pack this upcoming winter, especially with a warmer winter forecasted,” Walts said. 

However, Walts said from now through December, there is going to be a “good stretch of moisture potential” for the High Plains that will help with drought relief. 

“I think there’s enough support that there can be snow and some improvement in drought conditions,” Walts said. “Farmers should feel, at the very least, optimistic about what the forecast looks like.” 

Snowfall in Drought-Impacted Areas

Regions of the eastern U.S. are also forecasted to have below-average snowfall this winter. Walts said there is a consistent signal for western parts of the country to have a cooler winter, while the eastern half will be warm. Ohio and West Virginia still have areas of exceptional drought, according to the U.S. Drought Monitor. The most recent Crop Progress Report rated Ohio’s topsoil moisture condition 68% “very short/short.” According to Walts, it may be a “miserable” winter for snow enthusiasts in the eastern U.S. 

“Areas from the eastern Ohio Valley and up the East Coast could be a good bit below normal for snowfall this winter, which is important because some of those areas are in drought conditions,” Walts said. 

The winter outlook for the central U.S. is variable. La Niña’s effect on the winter jet stream and where it lands may determine how the Midwest’s winter plays out. Walts calls the Midwest a “battleground” and said it can be difficult to predict. He said Minnesota, Wisconsin, and northern Iowa have greater chances for snow systems than states like Illinois, Missouri, and Indiana.  

“The further north you are this winter, the higher the opportunity for above-normal snowfall, which is different than last year,” Walts said. 

Wild Card Factors 

Other oceanic and atmospheric patterns can make an impact when there is a weak La Niña. Observing sea surface temperatures in the North Pacific Ocean near Japan and south of Alaska can help predict U.S. winters. Walts said that when it is colder in Alaska, the U.S. has milder winters. 

“Based on ocean temperatures, the signal to me says there’s an above-normal risk that Alaska could be cooler and it could be a more mild winter in the United States,” Walts said. 

The other factor that could influence or shake up this winter’s predictions is the behavior of the polar vortex located at the North Pole. Walts compared the polar vortex to a dreidel, and that when atmospheric winds slow down, there is greater chance for the cold to stretch and elongate into the U.S. He said there is always a possibility for that to occur this winter, but impossible to predict where it would take effect. 

“This winter, I do think there’s an above-normal chance that it stretches, which means that there can be colder spells that sit south,” Walts said. “The question is, where does that go?”