U.N. Warns El Niño Is Being ‘Supersized Before Our Eyes.’ What It Means for Fall and Winter Weather
El Niño is being “supersized before our eyes,” the United Nations warned last month, putting the world in what U.N. Secretary-General António Guterres called “the danger zone of extreme weather.” Since then, the data has only grown more striking.
In a Sept. 10 update, NOAA’s Climate Prediction Center said sea surface temperature anomalies in the eastern equatorial Pacific had topped +3.0°C. The agency raised the odds of a “historic event” for October through December to 75%, up from 69% in August. In NOAA’s terminology, a historic event would be the strongest El Niño since at least 1950.
The latest weekly readings show the warming is still intensifying. For the week of Sept. 23, sea surface temperatures in the Niño 3.4 region — the central Pacific stretch scientists use to gauge El Niño — were 3.1°C above average, according to NOAA. That was up from about 2.6°C in mid-August. Off South America’s coast, readings ran 4.7°C above average. NOAA’s next monthly El Niño update is due Oct. 8.
New data also indicates an “exceptionally high likelihood of nearly 100%” that the current El Niño will continue until February 2027. This year’s event officially formed in June. The World Meteorological Organization expects it to persist through fall and winter, with its peak projected for late this year.
El Niño is a natural climate pattern, but its effects are unfolding against a backdrop of record global heat and ocean warming. The stronger the event, the greater its potential to rearrange rainfall and temperature patterns worldwide and fuel extreme weather.
“The science leaves no room for doubt: the planet is in uncharted waters, and those waters are heating up,” Guterres said in a statement Thursday. “Sea surface temperatures are rising, temperatures keep climbing, and the world is in the danger zone of extreme weather. The race now is between rising risks and our commitment to take climate action and protect people. We must win that race.”
WMO Secretary-General Celeste Saulo added: “We are already seeing disruption and devastation from droughts and floods and we expect these impacts to increase as El Niño intensifies.”
What El Niño means for North America
In North America, El Niño tends to make the South wetter, the North milder and the Atlantic hurricane season quieter. Its most significant effects on U.S. weather usually emerge in the fall and peak in winter.
“El Niño tends to increase the storm track over the southern tier of the United States, increasing the chances of above-average precipitation,” Michelle L’Heureux, a physical scientist at NOAA’s Climate Prediction Center, told Yahoo News in August.
Broadly, northern parts of the country could see warmer temperatures, while some areas may be drier than normal. L’Heureux said the southward shift in the storm track can leave parts of the northern U.S. drier than usual and raise the likelihood of above-average temperatures.
Every El Niño is unique in how it evolves, where its effects appear and how strong those effects are. Still, past strong events offer clues.
A strong El Niño typically brings wetter and cooler-than-normal conditions from late fall through winter. Thunderstorm activity often increases along the Gulf Coast and in the lower Mississippi and Tennessee valleys. Spring and summer wildfire risk also tends to decrease across the Southeast.
In the Southwest, El Niño often brings wetter-than-normal conditions, especially at midwinter, though the signal is less consistent than in the Southeast. Increased precipitation can reduce spring and summer wildfire risk in parts of the Southwest, including the Great Basin and southern Rockies.
A strong or very strong El Niño typically brings milder conditions and below-normal snowfall as Pacific air limits the buildup of cold air over western and central Canada. Parts of the Rockies can still receive above-normal snowfall, while the northern U.S. tends to be warmer and drier, which can increase spring wildfire risk in the Northern Rockies.
Winters are often drier than average across the Ohio and Tennessee valleys. At the same time, El Niño can increase thunderstorm activity from the lower Mississippi Valley into the Tennessee Valley.
In the Northeast, a strong El Niño generally means a milder winter with below-normal snowfall across much of the region. Even in a warmer pattern, the risk of powerful coastal storms, including nor’easters, can remain elevated.
A strong or very strong El Niño typically strengthens the subtropical jet stream during fall and winter, steering more storms across the southern U.S. and suppressing Atlantic hurricane activity, said Steven DiMartino, chair of the American Meteorological Society’s Board of Digital Meteorologists.
That pattern is already playing out. The eastern Pacific has produced a string of hurricanes since September, and two — Nolo and Rachel — were still active Saturday. The National Hurricane Center gave another system off southern Mexico an 80% chance of forming next week. In the Atlantic, which has been historically quiet, forecasters said no tropical storms are expected in the next seven days.
“While you only need one hurricane to have significant impacts, a very strong El Niño produces significant wind shear in the tropical Atlantic,” DiMartino said. “That prevents most tropical waves from forming and threatening the U.S.”
“The biggest impacts from El Niño tend to occur in the winter months, though the effects may linger beyond the winter,” Nat Johnson, a physical scientist at NOAA’s Climate Prediction Center and lead of the El Niño Southern Oscillation team, told Yahoo News.
Johnson added that the following spring and summer can bring higher or lower wildfire risk, depending on the region.
Forecast models point to a powerful event
Forecast models increasingly point to an unusually powerful El Niño. In its Sept. 10 update, NOAA raised the odds of a “historic event that would exceed the strength of previous El Niño events dating back to 1950” to 75%, up from 69% in August. The agency kept the odds of a “very strong” event above 90%.
CNN reported on Sept. 14 that El Niño had “leveled up to super status” after the Relative Oceanic Niño Index reached 2.0°C above normal — the threshold at which forecasters describe an event as “super.” AccuWeather meteorologist Alex DaSilva told Newsweek that the current El Niño is “the strongest on record to date if you take the daily value.”
Scientists declare that El Niño has formed when temperatures in the key central Pacific region known as Niño 3.4 run 0.5°C above average for several consecutive months, according to NOAA. If temperatures average 0.5°C above normal, the event is weak; 1°C is moderate; 1.5°C is strong; and 2°C is very strong.
According to WMO findings released Sept. 3, weekly sea surface temperatures in the Niño 3.4 region between late July and mid-August ranged from about 2.2°C to 2.6°C above average. In some areas, subsurface ocean temperatures were more than 8°C above average during July and early August — a sign of continued intensification.
Berkeley Earth, a nonprofit climate research group, said in an Aug. 13 analysis that it projected a peak near 4°C around November, which would make this the strongest El Niño in the observational record.
The group also noted that July 2026 was provisionally the second-warmest July on record, amid extreme weather worldwide. “Extreme heat and wildfires affected much of the Northern Hemisphere. Western Europe recorded its hottest June–July period on record, with major wildfires across the Mediterranean, while Canada saw extensive wildfire activity,” Berkeley Earth said.
Whether 2026 becomes the hottest year on record remains to be seen, but 2027 is far more likely to break the previous record. As Berkeley Earth climate scientist Zeke Hausfather told the Associated Press in August, “It’s going to keep getting worse.”
“The current trends and developments support that this El Niño will surpass the 1997-98 and 2015-16 events, which are considered the strongest on record,” DiMartino told Yahoo News. “Given that El Niño’s peak is in late November, the potential to rise by as much as 3°C to 4°C is becoming increasingly likely.”