An El Niño is developing rapidly in the tropical Pacific, and forecasters think it may be one of the strongest ever measured.

NOAA puts the probability above 90 per cent that it becomes a very strong event during the northern hemisphere autumn and winter, and at 69 per cent that it reaches historic intensity between October and December — exceeding any El Niño recorded since 1950 under the current measurement system. The World Meteorological Organization gives a probability approaching certainty that it persists until at least February 2027.

What El Niño is

Normally, trade winds blow east to west across the tropical Pacific, pushing warm surface water toward Asia and allowing cold water to rise along the South American coast.

During an El Niño those winds weaken or reverse. Warm water spreads back east across the basin, suppressing the upwelling of cold water. The Pacific is large enough that this rearranges atmospheric circulation globally, shifting where storms form and where rain falls.

The typical effects are reasonably well established: drier conditions across parts of Southeast Asia, Australia and southern Africa; wetter conditions along the west coast of South America and across the southern United States; suppressed Atlantic hurricane activity and enhanced Pacific activity; and a boost to global average temperature, since the ocean releases heat to the atmosphere.

That last effect is why models project 2027 as a candidate for the hottest year globally on record. An El Niño does not create warming; it redistributes heat already in the system, on top of an underlying trend.

The transition

What makes this year unusual is the swing. The world is moving from a moderate La Niña in 2025–26 — El Niño’s cool counterpart — into what may be a record-beating El Niño for 2026–27.

Rapid transitions of that kind are harder for agricultural and water systems to absorb than a sustained state in either direction, because planning made under one regime is invalidated by the other. A region that adjusted to drought conditions may face flooding, and vice versa.

The WMO’s secretary-general Celeste Saulo has said that if the current trajectory continues, the event may be stronger than anything since monitoring began — beyond the charts used for the past four decades.

How to read the probabilities

Seasonal forecasts are stated as probabilities because that is genuinely what is known, and the numbers deserve to be read as given rather than rounded up into certainty.

A 69 per cent chance of historic intensity means roughly three chances in ten that it does not happen. That is not a small residual. A forecast of this kind is a statement about the distribution of plausible outcomes, not a prediction of one.

Two further cautions. Regional impacts are much less certain than the basin-scale signal — knowing an El Niño is coming tells you considerably less about rainfall in a particular district than headlines suggest. And a strong El Niño makes certain outcomes more likely without guaranteeing any of them; individual seasons have repeatedly departed from the textbook pattern.

Why it is worth watching now

Because the lead time is the whole value of the forecast. Unlike most weather, El Niño develops over months and is visible in advance, which gives governments, farmers, insurers and humanitarian agencies an unusual opportunity to prepare.

Humanitarian organisations have argued for years that anticipatory action — releasing funds before a predicted drought rather than after it — is both cheaper and more effective than emergency response. The evidence supporting that is reasonably strong. The obstacle is institutional: funding systems are built to respond to suffering that has already occurred and are poorly designed to act on a probability.

The regions most exposed to El Niño-driven drought include several already covered on this site as underfunded crises. A forecast issued in September gives months of warning. Whether anyone acts on it is a separate question.

Sources

• NOAA El Niño/Southern Oscillation probability forecasts, September 2026
• World Meteorological Organization statements, including remarks by Secretary-General Celeste Saulo, carried by Al Jazeera
• Yale Climate Connections on the transition from the 2025–26 La Niña
• NOAA National Centers for Environmental Information climate report, 9 September 2026
• Published literature on ENSO teleconnections and on anticipatory humanitarian action