La Niña has arrived, forecasters say. What does this mean for our weather?
La Niña has officially arrived, federal forecasters say Climate Prediction Center It was announced on Thursday, October 9.
“La Niña conditions emerge in September 2025, as evidenced by an expansion of below-average sea surface temperatures across the central and eastern equatorial Pacific Ocean,” the forecast center said in a statement. he said.
As for how long it will last, “La Niña conditions are preferred to last through February 2026,” according to the center.
Forecasters say this La Niña could impact the end of the 2025 hurricane season and could also affect fall and winter weather in the United States.
What is La Niña?
La Niña is part of the natural climate cycle, officially known as the El Niño-Southern Oscillation and referred to by scientists as ENSO. The cycle alternates between warmer and cooler seawater in a region along the equator in the tropical Pacific. La Niña is marked by cooler-than-average ocean water in the region.
It is one of the main drivers of weather in the United States, especially in the late fall, winter and early spring. This is in contrast to the better-known El Niño, which occurs when Pacific Ocean water is at least 0.9 degrees warmer than average for three months.
The intermediate phase is known as ENSO-Neutral, when neither La Niña nor El Niño is present.
Typical impact of La Niña on seasonal hurricane activity in the Pacific and Atlantic.
How might it affect hurricane season?
Alex DaSilva, AccuWeather’s chief hurricane expert, said: online prediction The emergence of La Niña “promotes an active end to the hurricane season.”
So far, as of October 8, 10 storms have formed in the Atlantic, 4 of which are hurricanes. An average season sees 14 storms and seven hurricanes.
Tropical storms, especially in November, can be affected by La Niña, according to Matthew Rosencrans, a hurricane seasonal forecaster. National Oceanic and Atmospheric Administration.
“La Niña conditions are associated with more activity (twice the amount) in November compared to ENSO Neutral, and especially compared to November months with El Niño conditions,” he said in an email to USA TODAY.
When the La Niña phase occurs, less wind shear occurs in parts of the Atlantic basin where tropical air develops, increasing the potential for more storms, AccuWeather said.
Hurricane season officially ends on November 30.
Typical winter effects of La Nina in the United States.
How will this La Niña affect our winter weather?
A typical La Niña winter in the United States brings cold and snow to the Northwest and unusually dry conditions to many of the southern states. Climate Prediction Center. The Southeast and Mid-Atlantic also tend to see above-average temperatures during a La Niña winter.
In the East, the northern branch of the jet stream tends to carry faster-moving, less intense storms, which can mean near-average or even below-average snowfall and temperatures closer to seasonal norms, AccuWeather said.
Federal forecasters will release the government’s official winter outlook on Oct. 16.
Why is prediction important?
“Seasonal forecasts for El Niño and La Niña and their impact on our weather are an important climate intelligence tool,” said Celeste Saulo, secretary-general of the World Meteorological Organization. final statement.
“They represent millions of dollars in economic savings for key sectors such as agriculture, energy, healthcare and transportation, and have saved thousands of lives when used to guide preparedness and response actions,” he added.
This article first appeared on USA TODAY: La Niña has arrived. What does this mean for our weather?
