Three of the world's leading meteorological agencies are watching the same warming Pacific and arriving at different verdicts about 2026's El Niño — not because any of them is wrong, but because each is asking a subtly different question about what strength truly means. The debate reveals something quietly profound: in a world reshaped by climate change, even the tools we use to measure nature must themselves be remeasured. What all agencies agree on is that something exceptional is unfolding, and that its final place in history will only be known once it has passed.
Record El Niño? Depends who's counting
Only when it ends will scientists know where it truly belongs in history
Mark
So we have three major agencies and they can't agree on whether this is actually a record. How is that possible if they're all looking at the same ocean?
Mimi
They're looking at the same ocean but asking different questions. The Met Office is asking: what are the raw temperatures? Japan is asking: how far above normal are they? The US is asking: how is the ocean and atmosphere working together? Each answer is correct within its own framework.
Luke
But that's a problem, isn't it? If you can't compare them directly, how does anyone know what's actually happening?
Mimi
That's exactly why the agencies are updating their methods. The old baseline—a 30-year average—doesn't account for the fact that the entire ocean is warming. So "normal" keeps moving.
Mark
And the new method fixes that?
Mimi
It tries to. NOAA's new index measures the east-central Pacific against the rest of the tropical ocean, not against a fixed historical average. That difference is what actually drives weather impacts.
Luke
So the new index is more predictive of real-world effects?
Mimi
That's the theory. Under the old index, some El Niños looked weaker than they actually were in terms of weather disruption, and some La Niñas looked stronger.
Mark
When will we know if this one is actually the strongest?
Mimi
Not until it ends. Right now NOAA says there's a high chance it will be the strongest in their records going back to 1950, but they're still waiting for the final data.
Luke
So all three agencies could still be right, and we just won't know the full picture until this is over?
Mimi
Exactly. They're not contradicting each other—they're using different lenses on the same phenomenon.
Il Polso
- Three major agencies — Britain's Met Office, Japan's Meteorological Agency, and the US NOAA — are each calling 2026's El Niño record-breaking by their own metrics, yet their rankings contradict one another.
- The tension is methodological: raw temperatures, historical anomalies, and ocean-atmosphere coupling ratios each tell a different story, making a definitive global ranking impossible mid-event.
- Climate change has quietly corrupted older measurement baselines, causing some El Niños and La Niñas to produce weather effects wildly out of step with their official ratings.
- NOAA has responded by switching to a new Relative Oceanic Niño Index that measures the Pacific's warmth against the entire tropical ocean — not just its own past — better predicting real-world weather impacts.
- Scientists say the current event is almost certainly among the most powerful ever recorded, but the final verdict must wait until the El Niño ends and the full data can be assessed.
Three of the world's leading meteorological agencies are watching the same warming Pacific and arriving at different verdicts about 2026's El Niño — not because any of them is wrong, but because each is asking a subtly different question about what strength truly means. The debate reveals something quietly profound: in a world reshaped by climate change, even the tools we use to measure nature must themselves be remeasured. What all agencies agree on is that something exceptional is unfolding, and that its final place in history will only be known once it has passed.
Three major weather agencies are observing the same Pacific Ocean and reaching different conclusions about whether 2026's El Niño is the strongest on record. Britain's Met Office calls it unprecedented based on raw sea-surface temperatures. Japan's Meteorological Agency says it has surpassed the famous 1997 event by measuring how far temperatures deviate from a historical baseline. The United States' NOAA, tracking a slightly different Pacific region and emphasizing the relationship between ocean and atmosphere, says it has not yet exceeded its own historical records. They are not contradicting each other — they are simply measuring different things.
El Niño disrupts the Pacific's normal rhythm every two to seven years, causing trade winds to falter and warm water to surge eastward toward the Americas. That shift in where ocean heat enters the atmosphere reshapes weather globally, making some regions wetter and others drier. Measuring the strength of that disruption turns out to be surprisingly complicated, and the stakes of getting it right have grown as climate change accelerates.
For decades, agencies used baselines tied to 30-year historical averages, but warming oceans kept shifting those baselines upward, creating mismatches between official ratings and actual weather impacts. NOAA has now adopted a Relative Oceanic Niño Index, which measures how warm the east-central Pacific is compared to the rest of the tropical ocean — the difference that actually drives the weather people experience. The World Meteorological Organization is making the same transition.
Using this revised index, NOAA projects the current El Niño could surpass the legendary events of 1982-83, 1997-98, and 2015-16 if a key temperature threshold is reached — which the agency considers likely but not yet certain. Scientists emphasize that wherever this event ultimately ranks, it offers a rare opportunity to study an extraordinary climate phenomenon unfolding inside an already-warming world. Only when it ends will the full picture come into focus.
Three major weather agencies are looking at the same Pacific Ocean and reaching different conclusions about whether 2026's El Niño is the strongest on record. Britain's Met Office calls it unprecedented. Japan's meteorological authority says it's the most powerful ever observed. The United States National Oceanic and Atmospheric Administration says it still trails the biggest events in its own historical records. They are not contradicting each other. They are simply measuring different things.
The Pacific Ocean's El Niño Southern Oscillation is the planet's dominant natural climate engine. Under normal conditions, trade winds push warm water westward across the equator toward Asia while cold water wells up from below to replace it off South America's coast. El Niño disrupts this rhythm every two to seven years, lasting nine to twelve months. The trade winds falter. Warm water surges back eastward toward the Americas. That shift in where ocean heat enters the atmosphere reshapes weather patterns globally—some regions grow cooler and wetter, others hotter and drier.
Measuring how strong an El Niño is turns out to be surprisingly complicated. The Met Office bases its "unprecedented" assessment on raw sea-surface temperatures in the central equatorial Pacific, which it says have now exceeded levels from all previous El Niño events in its records. Japan's Meteorological Agency, by contrast, looks at temperature anomalies—how far current readings deviate above a historical baseline—in a specific region called Nino3. By that measure, the current event surpassed the famous 1997 El Niño, which had held the record since observations began in 1949.
The United States monitors a neighboring region, Nino3.4, in the east-central Pacific. American forecasters declare an El Niño official when temperatures there run at least 0.5 degrees Celsius above normal and the atmosphere responds by weakening trade winds and shifting tropical rainfall eastward—a process called ocean-atmosphere coupling. This focus on the relationship between ocean and atmosphere, rather than temperature alone, reflects a deeper scientific question: what actually matters for predicting weather impacts?
That question has become urgent as climate change accelerates. For decades, the National Oceanic and Atmospheric Administration and other agencies, including the United Nations' World Meteorological Organization, used the Oceanic Nino Index, which compared temperatures to a 30-year average updated every five years. But with oceans warming worldwide, that baseline kept shifting upward, creating a mismatch between what the index said was happening and what weather actually occurred. La Niña years—when the tropical Pacific was cooler than normal—sometimes produced stronger weather effects than their ratings suggested, while some El Niños produced weaker ones than expected.
NOAA has now switched to the Relative Oceanic Nino Index, which measures not just how warm the east-central Pacific is compared to its own historical average, but how warm it is relative to the rest of the tropical ocean. That difference—not the absolute temperature—is what drives the weather impacts people experience. The World Meteorological Organization is in the process of making the same shift. Emily Becker, a climate scientist at the University of Miami, explained the reasoning: "We were finding a mismatch between the temperature of the tropical Pacific and the impacts." The new index corrects for that disconnect.
Using this revised measurement, NOAA projects the current El Niño will be the strongest in its records, which extend back to 1950, if the three-month average reaches 2.5 degrees Celsius or higher—a threshold that would place it above the legendary 1982-83, 2015-16, and 1997-98 events. The agency rates the chances of reaching that level as high, though not yet certain. Becker emphasized that regardless of where this event ultimately ranks, it represents an extraordinary opportunity to study a powerful climate phenomenon unfolding within a warming world. Only when the El Niño ends will scientists have enough data to say with confidence where it truly belongs in history.
Citazioni salienti
By any measure, we are looking at a very strong El Niño, and only once it is over will scientists be able to assess how big it is and where it fits in the context of history.— Emily Becker, climate scientist, University of Miami
We were finding a mismatch between the temperature of the tropical Pacific and the impacts—La Niña years were producing stronger effects than their rating suggested, and El Niños weaker ones.— Emily Becker, on why NOAA updated its measurement method
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