There is a patch of ocean along the equator, stretching west from the coast of South America, that quietly governs the weather for a large share of humanity. When it warms by a couple of degrees, the effects do not stay in the Pacific. They travel. Rain that belongs in Indonesia falls instead on the deserts of Peru. Fish vanish from one coastline and the fishermen who depend on them go hungry. A jet stream bends a few hundred miles south and, months later, tornadoes touch down in Florida in the dead of winter.
That patch of ocean is warming again.
On May 14, 2026, NOAA's Climate Prediction Center raised its alert to an El Niño Watch, putting the odds of an El Niño emerging by midsummer at 82 percent and climbing to 96 percent by the heart of winter. More striking than the timing is the strength. Forecasters now consider a "super" El Niño — one where the key stretch of Pacific runs at least 2°C above normal — the most probable single outcome for late this year, and some model guidance suggests it could rival the most powerful events on record. To understand what that means, it helps to look at the last two times the ocean did this.
What El Niño actually is
In a normal year, trade winds drag warm surface water westward across the Pacific, piling it up near Indonesia and letting cold, deep water rise along South America. El Niño is what happens when those winds slacken and the warm water sloshes back east. The whole atmospheric engine that sits on top of the Pacific shifts with it. Storm tracks move. The places that are usually wet go dry, the dry places flood, and the disruption radiates outward through the global system of winds that meteorologists call teleconnections.
A "super" El Niño is simply the same machine running hot. The warming is more extreme, so the downstream effects are larger and reach further. There is no committee that certifies the label; it is shorthand for an event near the top of the historical scale, like the two that bracket recent memory.
1997–98: a tour of opposite extremes
The El Niño that formed in 1997 became one of the most powerful ever recorded, and what makes it such a useful teacher is how contradictory its damage was. The same event that drowned one region parched another.
California saw record rainfall, flooding, and landslides, and abnormally high seas battered the San Francisco Bay shoreline. Across the Pacific, Indonesia endured one of its worst droughts on record: a cereal shortfall of more than three million tons, and uncontrolled fires that choked the region in haze and fed into the economic and political crisis then engulfing the country. In the Horn of Africa, the opposite catastrophe — torrential rain and flooding in Kenya and Somalia — triggered outbreaks of cholera, malaria, and Rift Valley fever. In South America, flooding killed thousands across Ecuador, Peru, and Bolivia.
And then there was Florida. During the overnight hours of February 22–23, 1998, the El Niño-strengthened jet stream, displaced south over the state, helped spawn seven tornadoes through Central Florida that killed 42 people — still the deadliest tornado event in the state's history. In a final twist that captures the whole pattern, the heavy El Niño rains that greened Florida's underbrush set the stage for the severe wildfires that swept the same state months later when the rain abruptly stopped. Flood, then fire, from one ocean anomaly.
The bill was staggering. Damage estimates ran from $32 to $96 billion, and one 2023 analysis in the journal Science put the long-tail global economic losses, traced over the following years, in the trillions. Crucially, the suffering was not evenly distributed. The deaths, the famines, the disease clusters fell hardest on the poorest and most exposed populations — the subsistence farmers, the coastal communities, the places with the least cushion to absorb a shock they did nothing to cause.
2015–16: the reefs paid
The next great event arrived in 2015, and its signature catastrophe happened underwater.
Corals live close to their thermal limit. Push the water a degree or two too warm for too long and they expel the algae that feed and color them, turning bone-white and, if the heat lingers, dying. El Niño years are when that heat arrives, and the 2015–16 event delivered it at planetary scale: researchers later concluded it produced unprecedented global coral heat stress across the world's oceans. NOAA called the resulting die-off, which stretched from 2014 into 2017, the longest global bleaching event on record. Australia's Great Barrier Reef suffered some of its most severe bleaching ever documented in 2016. The 1998 super El Niño had already killed an estimated sixteen percent of the world's reefs; the 2016 event hammered what remained.
Why this time the rules may have changed
Here is the part that should give anyone pause, and the reason history is only an imperfect guide.
Every previous El Niño struck a cooler planet. This one will land on top of the warmest baseline in human history, and that changes the arithmetic. A strong El Niño, as climate scientist Daniel Swain has described it, acts like a "mini, temporary, but natural global warming," dumping stored ocean heat into the atmosphere and lifting the global average by a few tenths of a degree. Stack that pulse on an already record-warm world and 2026 or 2027 could set new heat records outright.
The reefs make the danger concrete. A 2016 study in Science found that decades ago, gentle pre-season warm spells used to prime corals to survive the hot months — a kind of natural vaccination. Modern heat now comes on too fast and too strong for that protection to work. Worse, scientists analyzing the 2016 Great Barrier Reef bleaching concluded the mass mortality would have been unlikely without global warming amplifying the El Niño signal. And the most ominous data point of all: the Great Barrier Reef bleached severely again in 2017 with no El Niño at all. The background warming alone had become enough. El Niño is no longer the sole trigger; it is now an accelerant thrown onto a fire that was already lit.
This is also why forecasters hedge. An El Niño this far out carries real uncertainty — the spring is a notoriously difficult season to predict through — and a warming climate may be reshaping how El Niño's effects ripple across the globe in ways the historical record can't fully anticipate. The pattern that produced Florida's tornadoes or Indonesia's fires may not repeat in exactly the same places or the same magnitudes. The honest position is that we know a large event is very likely, and we know it will arrive on a planet primed to amplify it, but the specific map of who gets the flood and who gets the drought is drawn fresh each time.
What it adds up to
A super El Niño is not a single disaster in a single place. It is a year, or two, of the planet's weather running off its usual rails simultaneously, with the costs landing unevenly and the heaviest blows falling where people can least afford them. The last two events together touched hundreds of millions of lives and reshaped marine ecosystems that will take decades to recover, if they recover at all.
There is one piece of genuine good news buried in the history. After 1997–98, an international study with a memorable subtitle — Once Burned, Twice Shy? — argued that the difference between catastrophe and manageable hardship lies almost entirely in forecasting and preparation: reliable warnings, and governments willing to act on them before the water rises. The forecast this time is early, and it is clear. The Pacific has shown its hand. What we do with the warning is the part history can't predict.
