La Niña Could Arrive Soon; Here’s What It Means For Winter Snowfall

A slowly developing La Niña climate pattern is expected to influence how winter 2024-25 plays out in after last year’s unusually warm El Niño winter.

The 2024-25 winter outlook released Thursday by the National Oceanic and Atmospheric Administration’s Climate Prediction Center said winter could be wetter-than-normal — and perhaps snowier — over the entire northern tier of the continental U.S. but drought conditions could persist in other areas of the country.

El Niño and La Niña are opposite phases of the El Niño-Southern Oscillation, a natural climate pattern that causes predictable changes in the tropical Pacific Ocean. They’re not the only factors in weather, but El Niño generally favors warmer, drier weather, while the opposite is true with a La Niña. Either can have an outsized effect during the winter months.

Forecasters originally expected a La Niña to develop late last winter, which turned out to be the warmest on record in the continental U.S. and worldwide.

“If it seems like we’ve been stuck here in neutral for longer than we expected — we have!” Emily Becker, an atmospheric scientist at the University of Miami, wrote in the National Oceanic and Atmospheric Administration’s latest La Niña/El Niño blog post.

The climate patterns are predictable, but only in the big picture. Small short-term fluctuations, such as the weaker equatorial trade winds during September, can’t be predicted more than a couple of weeks in advance, at best, Becker wrote.

Forecasters have about 60 percent confidence La Niña will develop ahead of the start of meteorological winter on Dec. 1 (the winter solstice on Dec. 21 is generally accepted as the official start of the season). But it is expected to be a weak one.

Strong La Niñas are associated with consistent weather throughout the season, but “a weaker event makes it more likely that other weather and climate phenomena could play the role of spoiler,” Becker wrote.

Overall, NOAA predicts wetter-than-average conditions for the entire northern tier of the continental U.S., particularly in the Pacific Northwest and the Great Lakes region, along with northern and western Alaska. Drier-than-average conditions are expected from the Four Corners region of the Southwest to the Southeast, Gulf Coast and lower mid-Atlantic states.
That could either ease or worsen drought conditions, especially in the central and southern Plains and the Southwest.

“Unfortunately, after a brief period in the spring of 2024 with minimal drought conditions across the country, more than a quarter of the land mass in the continental U.S. is currently in at least a moderate drought,” Brad Pugh, operational drought lead with NOAA’s Climate Prediction Center, said and the statement.

“And the winter precipitation outlook does not bode well for widespread relief,” he said