WMO Warns El Niño Could Rapidly Strengthen to Strong Levels by Late 2026
The World Meteorological Organization says El Niño conditions are developing in the tropical Pacific and could strengthen rapidly during July–September 2026, potentially reaching strong levels later in the year.
In its June 25 update, the WMO estimated an 80% probability that El Niño would emerge during June–August 2026. The agency put the probability at about 90% for September–December 2026, signaling that the transition from developing conditions to an established climate pattern is increasingly likely.
The forecast is not a prediction that every region will experience the same weather. El Niño changes the odds of particular heat, rainfall and storm patterns, but its effects vary by location and it does not determine the outcome of every individual weather event.
A rapid strengthening forecast
The WMO’s July–September seasonal outlook projects a rapid development toward a strong El Niño event. Its multi-model ensemble forecasts an approximately 2.0°C seasonal anomaly for the relevant Niño index during that period.
That index measures ocean-atmosphere conditions in a key part of the tropical Pacific. A strong reading does not translate into one uniform global result, but it can influence seasonal climate patterns across multiple regions. The WMO says El Niño can contribute to major shifts in global weather and climate, including heatwaves and heavy rainfall.
The agency says El Niño typically reaches its peak between November and February. That timing means the July–September strengthening window could precede the period when the event’s influence is usually strongest. The eventual peak strength remains uncertain.
Why the forecast matters
El Niño is a worldwide climate development because changes in the tropical Pacific can affect atmospheric circulation far beyond the region. Depending on location, communities may face heightened risks from extreme heat, unusually heavy rainfall or other weather disruptions during the event’s development and peak periods.
The forecast gives governments, emergency planners and humanitarian agencies a defined period in which to assess risks and prepare. Those preparations must be tailored to local conditions: a signal associated with heavier rainfall in one area may coincide with increased heat or dryness elsewhere.
Forecast confidence is high that El Niño will emerge, but the WMO’s projections do not make a strong event certain in every detail. The agency’s probability estimates describe the likelihood of the climate pattern developing, while the model projection indicates the potential scale of the ocean-temperature anomaly.
Climate risks are already imposing costs
In a separate late-July statement, UN Climate Change Executive Secretary Simon Stiell said climate-driven wildfires, heatwaves and floods were imposing major human and economic costs. The statement cited wildfires in France, Spain and elsewhere in Europe, along with heatwaves and floods, and linked the growing impacts to continued fossil-fuel burning.
Those events should not automatically be attributed to the developing El Niño. Event-specific attribution requires separate analysis. But the warning adds urgency to the WMO’s call for preparation as the Pacific climate pattern develops.
The next major forecasting milestones are the July–September development period and the typical November–February peak window. The strength of the eventual event, and the precise effects in individual regions, will become clearer as observations and forecasts are updated.
Sources
- Global Seasonal Climate Update for July-August-September 2026, World Meteorological Organization
- UN Climate Chief: The climate alarm is blaring, from every direction, UNFCCC
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