El Niño: New Forecast Updates Timeline for Winter Weather Event - Newsweek

El Niño has continued to strengthen, with a "strong-to-very strong" event likely through January-March 2027, according to a new federal forecast.

Meteorologists at the National Weather Service’s Climate Prediction Center (CPC) said there was a greater than 79 percent chance for such an event. They added that the phenomenon is expected to continue strengthening before a weakening trend begins early next year.

El Niño is a naturally recurring climate pattern associated with warmer waters in the Pacific that can influence temperatures and rainfall worldwide. In the U.S., typical El Niño effects can include wetter conditions across the South and warmer, drier conditions in the North during winter.

Forecasters say this episode has already smashed benchmarks and could help make 2027 the hottest on record.

The CPC said on Thursday there was roughly a 60 percent chance for a "historic event exceeding previous El Niños dating back to 1950” for the October-December and November-January periods.

"Even with a very strong El Niño, the chances of experiencing impacts consistent with El Niño are higher, though not guaranteed," the agency added.

The CPC also said, when compared to last month, "El Niño strengthened as sea surface temperature anomalies exceeded 4.0°C, extending farther westward across the eastern equatorial Pacific Ocean."

As for how the ongoing event could shape weather conditions across the U.S., Paul Pastelok, lead long-range expert at private weather company AccuWeather, told Newsweek: "We can expect a very active subtropical jet stream sending storms [to] the West Coast." The Southern U.S. can expect cool and fairly wet conditions, he said.

"The interior Northwest, upper Midwest, Great Lakes and much of the Northeast will have warmer-than-average temperatures, less arctic intrusions [and] less-than-average snowfall," the meteorologist added.

In its October update, the CPC said El Niño had strengthened and that there was a greater than 83 percent chance of a "strong-to-very strong" event through January-March 2027.

It previously said the event had a high chance of exceeding the strength of all previous El Niños dating back to 1950. There was a 54 percent chance of this happening between September and November; 83 percent chance for October-December; and 70 percent chance for November-January.

The National Oceanic and Atmospheric Administration (NOAA) released its winter outlook last month and the agency pointed towards El Niño playing a key role in shaping seasonal conditions.

The NOAA said warmer temperatures than average are favored for Northern California, the Pacific Northwest, Midwest, Mississippi Valley, much of the East and Alaska. Near-normal temperatures are most likely for parts of the Southeast.

Meanwhile, it indicated wetter-than-average conditions are most likely along the southern tier of the country and across the East Coast. Hawaii, most of Alaska, the northern Mountain West and portions of the Great Lakes region could see drier conditions than usual, it added.

"As we know from decades of observations, a very strong El Niño will likely bring a southward and eastward shift to the jet stream for the contiguous U.S., which tilts the odds toward stormier weather across the South," Ken Graham, director of NOAA’s National Weather Service, said in the outlook.

"While higher chances of rain and snow may bring relief to drought-afflicted areas, too much precipitation on dry soil can fuel destructive flash floods and mudslides. Now is the time for communities and individuals to plan ahead for the upcoming winter," he continued.