US heading for unprecedented El Niño winter: Here's what to expect

The ongoing El Niño is breaching the "super" threshold as Earth crosses into unprecedented climate territory.

El Niño, officially underway as of June 11, is a climate pattern that's injecting extra heat into our already-warming world, threatening disruptive weather across the globe and a humanitarian crisis in some regions.

While El Niño is part of a natural multiyear climate cycle, scientists have noticed that it has been rapidly strengthening like never before, intensified by human-driven climate change, and putting stressed natural systems under extra strain.

In a new update this week, the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center continues to forecast a 75% chance that this El Niño event will be stronger than any previous El Niño since 1950, the earliest year from which NOAA has data to make historical comparisons. Furthermore, this El Niño appears to be going "super" ‪—‬ something that has been expected for weeks.

Weekly NOAA data from the eastern Pacific's El Niño region reveal that sea surface temperatures have reached 3.8 degrees Fahrenheit (2.1 degrees Celsius) above average, hitting the more than 3.6 F (2 C) threshold for a very strong or "super" event. Strictly speaking, NOAA uses three-month averages to categorize strength, as weekly data is more prone to temporary anomalies. But the latest data once again signals where this El Niño is heading, with NOAA forecasting a more than 90% chance of a very strong event emerging in the fall and winter.

How will El Niño impact the U.S.?

During El Niño, warmer waters gather east of the equatorial Pacific, forcing the jet stream south. The patterns associated with El Niño bring exceptionally stormy winter weather and a higher chance of rain and snow across California and Southern states, with Northern states experiencing fewer storms and a milder winter, according to the Climate Prediction Center. El Niño can also increase the risk of high-tide flooding, particularly on the West Coast, according to NOAA.

However, as with climate change in general, El Niño doesn't have the same impacts on all regions. Furthermore, while a more intense El Niño typically increases the certainty of expected impacts, they are not guaranteed.

The last "super" El Niño happened in 2015 and 2016. Associated impacts included a historic hurricane season in the central North Pacific and record drought in the Caribbean, according to Climate.gov. Before that, the last El Niño to go super was in 1997 and 1998. That winter was marked by a variety of extreme weather events, including flooding in the Southeast, an ice storm in the Northeast and tornadoes in Florida, according to a report by the National Climatic Data Center.

Already this year, tropical storms in Hawaii have been attributed to El Niño, with warming in the waters where storms typically form there, CNN reported. Meanwhile, the strengthening of El Niño in the Pacific appears to have left the Atlantic unusually calm. Ars Technica reported that the Atlantic hurricane season passed its traditional peak without a tropical storm or hurricane in what is becoming a historic period of quiet.

What is El Niño?

El Niño affects the whole planet, but it begins with unusually warm waters in the eastern tropical Pacific Ocean. NOAA recognizes El Niño conditions when these waters are at least 0.9 F (0.5 C) warmer than average, while wind, surface pressure and rainfall in the region are also consistent with El Niño conditions. An El Niño is then categorized based on its strength, from weak to very strong. Very strong El Niños (above 3.6 F, or 2 C, warmer than average) are nicknamed "super" El Niños, though this isn't a scientific term.

The European Centre for Medium-Range Weather Forecasts' El Niño models suggest that temperatures are sailing past the 2 C threshold and will exceed 6.3 F (3.5 C) by the end of the year. On Sept. 20, the daily El Niño temperature was 5.5 F (3.06 C), according to The Climate Brink. But while this year's El Niño is certainly supercharged, there's still uncertainty about its impacts.

El Niño forecast

On Sept. 3, the World Meteorological Organization (WMO) released a fresh set of El Niño warnings along with a Global Seasonal Climate Update, which the WMO said offers a more refined picture of expected conditions in the coming months.

"For September-November 2026, WMO multi-model forecasts indicate an increased likelihood of above-normal temperatures across almost all land areas, alongside rainfall patterns showing a pronounced and classic atmospheric response to the strong Pacific El Niño," WMO representatives wrote in a statement.

In other words, much of the world is likely to be hotter than normal, while some areas will experience more rainfall and others will see less. The most severe El Niño impacts will likely be felt outside North America.

Liz Stephens, a professor in climate risks and resilience at the University of Reading in the U.K., recently noted that the Indian monsoon season had seen less rainfall than normal and that satellite data revealed that parts of East Africa, Central America and Southeast Asia are experiencing record-dry conditions. The human impact of such weather can be devastating.

"During the large El Niño event of 1997/1998 the associated flooding in Somalia killed over 2000 people," Stephens said in a statement released Sept. 3. "With a bigger El Niño event on the way, and global temperatures now 0.7°C [1.26 F] higher and capable of holding even more moisture as a result of climate change, scientists are concerned that there is potential for even more severe flooding."