An El Niño-like pattern of warmer than average sea surface temperatures is emerging in the equatorial Pacific Ocean as of May 17, 2026. There are four key El Niño monitoring regions, but the one that has the biggest influence on global climate patterns is called Niño 3.4. Credit: Ben Noll/the Washington Post/NASA

A vast pulse of warm water is moving east beneath the tropical Pacific. You can’t see much of it from space, because most of the action is below the ocean surface, and satellites can only map the surface ocean. But if that heat rises and links up with the atmosphere, it could fuel one of the most consequential climate events of the decade.

NOAA now says El Niño is likely to emerge soon, with an 82% chance during May–July 2026, and a 96% chance it persists through the Northern Hemisphere winter of 2026–27. But this could be a particularly devastating El Niño.

What El Niño actually is

El Niño is one of the planet’s most important climate patterns. It starts in the tropical Pacific, when unusually warm water spreads eastward across the ocean surface. That may sound remote, but it matters everywhere. The warm water changes where tropical storms form, where rain falls, and how jet streams move. A strong El Niño can bring floods to some regions, drought and fire risk to others, disrupt fisheries and crops, and temporarily push global temperatures higher.

And this one has scientists on alert because a large reservoir of heat is already moving beneath the Pacific. If that heat reaches the surface and the atmosphere responds, 2026 could bring a powerful El Niño — maybe even one of the strongest on record.

Technically speaking, El Niño is the warm phase of the El Niño–Southern Oscillation, or ENSO, a natural climate cycle centered in the tropical Pacific. Under normal conditions, trade winds push warm surface water west toward Indonesia and Australia. Near South America, colder, nutrient-rich water rises from below.

During El Niño, that pattern weakens. The trade winds slow or even reverse and warm water spreads east across the equatorial Pacific.

This year, unusually strong westerly wind bursts appear to have launched a Kelvin wave, a broad pulse of warm water moving below the surface. This wave is carrying an unusual store of heat.

“The current Kelvin wave is impressive and, by some measures we look at, it is rivaling the one we saw in 1997,” said Michelle L’Heureux, a physical scientist at NOAA’s Climate Prediction Center, according to The Washington Post.

That comparison is ominous. The 1997–98 El Niño was one of the strongest ever observed.

Kelvin waves deepen the warm layer of the ocean and weaken the cold upwelling off South America. When that cool supply shuts down, surface waters heat up. El Niño begins to lock in.

Why This One Looks Different Satellite data captured the 2015 super El Niño as warm water spread across the Pacific. A similar event may be building now, this time against a hotter global backdrop. Credit: Michala Garrison/NASA Earth Observatory

Strong El Niños have struck before, including in 1982–83, 1997–98 and 2015–16. A suspected super El Niño in 1876–77 coincided with catastrophic famine across parts of India, China, Brazil, and Africa.

But in 2026, the background is different; simply put, everything is worse climate-wise. The oceans are warmer now, as is the atmosphere. A strong El Niño could have devastating effects.

The planet is much hotter nowadays. Credit: Ben Noll/The Washington Post/ECMWF

Still, forecasters are being careful. The agency says there is still substantial uncertainty around the eventual peak strength, and that strong El Niños do not automatically produce strong impacts everywhere.

NOAA’s May 2026 forecast gives a two-in-three chance that this event becomes strong or very strong by late 2026 or early 2027. That forecast uses NOAA’s newer Relative Oceanic Niño Index, which tries to separate the El Niño signal from the broader warming of tropical oceans. In other words, the El Niño signal is standing out even against a tropical ocean that is already unusually warm.

Scientists are also watching a rare ring-like pattern of warmth in the Pacific called annular warming. In model experiments, researchers found that the Pacific already held enough heat for a moderate El Niño. When they included this unusual ring of warmth, the forecast intensified toward super El Niño territory.

“I would suggest there is roughly a 50% chance of the event becoming the strongest in the historical record right now,” Paul Roundy, a professor of atmospheric science at the University at Albany, told BBC Science Focus. “A few weeks ago, I was suggesting maybe 20%.”

What a Powerful El Niño Could Do

The effects would vary by region, but a strong El Niño tends to bring predictable problems.

Some regions face heavier rain and flooding. Others see drought and heat. The eastern Pacific hurricane season often becomes more active, while Atlantic hurricane activity can be suppressed by stronger wind shear. NOAA’s 2026 Atlantic hurricane outlook already points to a below-normal season, largely because of the expected El Niño.

The ocean impacts can be just as serious. Warm surface waters can cut off nutrient-rich upwelling off Peru and Ecuador, harming fisheries. Marine heat can stress coral reefs. Heat and drought can raise wildfire risk in parts of Australia, Southeast Asia, and the Amazon.

Food systems can also feel the shock. El Niño can disrupt rainfall during important growing seasons, especially where agriculture depends heavily on monsoons or predictable seasonal rain.

And then, of course, there’s the global temperature.

El Niño releases heat from the tropical Pacific into the atmosphere. That often pushes global average temperatures higher temporarily. If a strong event forms in 2026, its biggest global temperature impact may arrive in 2027, after the atmosphere has had time to respond.

Just the Start

El Niño is natural. Climate change isn’t causing the cycle itself.

But climate change changes the world in which El Niño unfolds. Heat extremes start from a higher baseline. Marine heat waves are more damaging because ecosystems are already under pressure.

That means a powerful El Niño today is worse than a powerful El Niño 50 or 100 years ago. This is why scientists are watching the Pacific so closely. The question isn’t just whether El Niño forms. NOAA already says that is likely. The harder question is how strong it becomes, and how forcefully it couples with a planet already running hot.

The next few weeks and months will be crucial.

If surface temperatures keep rising in the eastern and central Pacific, and if the atmosphere begins to respond, confidence in a strong event will grow. If trade winds recover, or if the warm subsurface pulse fails to fully surface, the forecast may ease.