(NEXSTAR) – After months of anticipation, La Niña has officially begun.
La Niña conditions emerged in September, the Climate Prediction Center announced on Thursday, and they’re expected to last through at least the end of the year.
La Niña typically reaches peak strength in the winter, meaning that’s when it has the greatest impact on the type of weather we see — especially precipitation. However, this year forecasters are expecting a pretty weak La Niña.
Here’s what that means for winter weather across the U.S. in 2025 and early 2026.
What happens during a typical La Niña winter?
La Niña impacts the position of the polar jet stream, therefore influencing the weather we see on land.
The jet stream divides the country in two, bringing wetter weather to the Pacific Northwest and Ohio Valley.
Meanwhile, we typically see dry, warm weather in the southern states. That can exacerbate drought conditions, especially in the Southwest and California — areas that rely heavily on winter rain.
“Here in the Washington, D.C. area, it generally rains all year round,” Mike Halpert, deputy director of the Climate Prediction Center, told Nexstar in 2022, as the country was bracing for a triple-dip La Niña.
“So if we have a couple of dry months, it’s OK because we can make it up another time. When you’re in California and the Southwest, 90% of the rain falls in that fairly short winter and spring season. So if you miss that, you’re not going to make that up when you get into the summertime.”
What happens during a weak La Niña winter?
A weak La Niña, as we’re expecting this year, can make it harder to predict the weather.
“A weak La Niña would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance,” said the Climate Prediction Center on Thursday.
Essentially, it’s less likely we’ll see a “typical” La Niña, but it’s still entirely possible we will. Last winter, for example, we also had a weak La Niña, but the impacts were pretty textbook:
“In particular, most of the southern U.S. and northern Mexico were predicted to be and turned out to be drier than average, with record-dry conditions in southern Arizona and parts of New Mexico,” explained meteorologist Nat Johnson. “Wetter conditions were forecasted and did prevail over the northern part of the continent, particularly in Alaska and parts of the Pacific Northwest, as well as much farther south in Central America.”
It wasn’t a perfect forecast — east Texas, Arkansas, Kentucky and western Virginia got some pretty wet weather — but overall, the La Niña pattern played out, Johnson said.
If this year’s La Niña turns out to be perfectly typical, the winter precipitation around the country would look like the map below: a dry season for California and the South, but a wetter or snowier season in the blue patches of the northern and Midwest states.
What happens next?
While La Niña is favored to stick around through most of winter, it could fade by early spring. The Climate Prediction Center said there’s a 55% chance we see a transition to “ENSO-neutral” between January and March of 2026. “ENSO-neutral” means neither La Niña nor El Niño is in effect.
It’s too soon to tell what will happen later in the year, but at this point, it’s looking more likely that we’ll see an El Niño forming than a repeat La Niña.
