La Niña is here. What this means for winter weather — and the rest of hurricane season.

La Niña is officially here, forecasters from the Climate Prediction Center announced in an advisory on Thursday morning.  

“La Niña conditions emerged in September 2025, as indicated by the expansion of below-average sea surface temperatures across the central and eastern equatorial Pacific Ocean,” read the prediction center’s statement.

As for how long La Niña will last, the advisory noted that “conditions are favored to persist through December 2025 — February 2026.” Currently, La Niña is expected to remain weak, which, the prediction center added, would be “less likely to result in conventional winter impacts.”

What is La Niña?

In the U.S., La Niña typically leads to warmer and drier conditions across the southern U.S., and cooler, wetter conditions across northern areas like the Pacific Northwest. It’s a recurring climate pattern that causes colder-than-normal temperatures in the eastern Pacific Ocean. This occurs because powerful winds push the warmer water to the west, resulting in colder surface water in the east. 

La Niña represents one of two extreme phases of the natural climate cycle known as the El Niño-Southern Oscillation. ENSO, for context, is a recurring climate pattern that results in changes in water temperatures in the central and eastern tropical Pacific Ocean, per the National Weather Service.

La Niña refers to the “periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific,” which typically occurs every three to five years, according to the Climate Prediction Center. The cooler the ocean temperature, the stronger the La Niña.

How will this La Niña affect winter weather in the U.S.?

Should this La Niña remain weak, as forecasters have suggested, the climate pattern’s influence on global weather patterns could have less impact than those of a strong La Niña. A weak La Niña, as Emily Becker, the lead writer of the National Oceanic and Atmospheric Administration’s ENSO blog, told Live Science, “wouldn’t exert a strong influence over the winter.” 

Because this La Niña is forecast to be weaker, the climate pattern’s traditional impacts — warmer, drier conditions across the southern U.S., and cooler, wetter conditions across the northern U.S. — may be less pronounced. 

“There is a three out of four chance it will remain a weak event,” Michelle L’Heureux, a climate scientist at NOAA’s Climate Prediction Center, told the Associated Press. “A weaker event tends to exert less of an influence on the global circulation, so it’s possible there will be surprises ahead.”

What this winter’s weather will look like also depends on how this La Niña interacts with a marine heat wave across the Northern Pacific Ocean, known as “the blob,” CNN notes. 

La Niña and the marine heat wave could work in tandem to change winter weather patterns, Elizabeth Maroon, an atmospheric scientist at the University of Wisconsin-Madison, told the outlet. Maroon noted that the question remains, “Will the marine heat wave get amplified by La Niña conditions, which is a very distinct possibility?”

How will this La Niña impact hurricane season?

Typically, a La Niña leads to increased Atlantic hurricane activity, by weakening the vertical wind shear in the tropical Atlantic and the Caribbean, which allows for the formation of bigger, more intense storms. While the climate pattern often amplifies the Atlantic hurricane season, some forecasters, like Brian McNoldy, a senior research associate at the University of Miami who studies tropical cyclones, believe that this La Niña will be too weak and fleeting to cause much damage. McNoldy told the Associated Press that he doesn’t anticipate that this La Niña will have a significant impact on the hurricane season.