WMO Assigns Nearly 100% Likelihood That El Niño Will Persist Until February 2027

An unprecedented degree of certainty

At a Geneva press conference on 3 September 2026, WMO officials released the August 2026 El Niño/La Niña Update with a forecast that broke new ground for the agency. Global Producing Centres showed an "exceptionally high likelihood of nearly 100%" that El Niño will persist through to February 2027.

Celeste Saulo told reporters this was the first time WMO had expressed such a degree of certainty in an El Niño/La Niña Update. "Nearly one hundred percent," she said. The figure reflects not a single model's output but strong agreement within WMO's extensive network of National Meteorological and Hydrological Services and climate prediction centres.

Previous updates have conveyed high probabilities, but the September release is qualitatively different. Forecasters describe the outlook as unequivocal, driven by persistent positive sea surface temperature anomalies across the central-eastern equatorial Pacific and reinforcing atmospheric signals that have locked the system into an El Niño state.

What nearly 100% means in practice

In probabilistic forecasting, no outcome is ever literally guaranteed. What WMO's language signals is that every major seasonal prediction system in its consortium points the same way, and that the oceanic heat content available to sustain the event is exceptionally large.

As of mid-August 2026, El Niño had become firmly established, marked by persistent and intensifying positive sea surface temperature anomalies. Forecasts indicate further strengthening in the coming months, with the event expected to reach very strong intensity. A return to ENSO-neutral conditions or La Niña is not anticipated during the outlook period.

Saulo emphasised that a huge pool of very warm ocean waters will fuel the intensity of El Niño. The phenomenon is expected to continue as a very strong event, possibly exceptionally strong, even as it approaches its peak towards the end of the year.

Implications for governments and humanitarian planning

The near-certainty of persistence through February 2027 gives planners a longer horizon than many El Niño episodes provide. Humanitarian agencies can allocate resources against a forecast that is unlikely to flip within a single season, rather than hedging against an early return to neutral conditions.

WMO is part of a core UN team working with UN Country Teams to manage risks associated with the 2026–2027 episode while identifying opportunities for building resilience. Saulo said seasonal forecasts provide a vital window of opportunity and that "we have no time to lose."

The press release accompanying the update notes that El Niño impacts will be felt long after the ocean peak, including on global temperatures. That extended tail is part of what makes the forecast's duration as significant as its intensity.

A benchmark for future ENSO communication

Climate scientists have noted that the clarity of this update may set a template for how WMO communicates extreme ENSO events when model agreement is unusually strong. The agency's updates are intended as the world's most authoritative source for governments and decision-makers, and the September 2026 release tested that authority against a forecast with little room for alternative outcomes.

For communities already experiencing drought, flood or heat linked to the developing event, the message is that the driver behind those anomalies is not expected to fade quickly. Preparation aligned to a multi-season El Niño, rather than a brief perturbation, is what the forecast implies.