The tropical Pacific is loading up for what could become one of the strongest El Niño events in recorded history, and the latest European forecast models are putting numbers to the threat that have caught the attention of governments, commodity traders, and disaster planners worldwide.
The Copernicus Climate Change Service (C3S) multi-system seasonal forecast, initialized on May 1, 2026, now shows more than half of its ensemble members pushing the Niño 3.4 sea-surface temperature index past +2.5 degrees Celsius above the 1981-to-2010 average before the forecast window closes. Upper-range model trajectories project Niño 3.4 anomalies approaching +3 degrees Celsius by fall, while the Niño 1+2 region, the strip of ocean hugging the South American coast where El Niño’s heat tends to concentrate most intensely, could spike toward +4.5 degrees Celsius by November.
If those upper trajectories verify, the event would rival or exceed the two benchmark super El Niños of the satellite era: 1997-98 and 2015-16.
What the European forecasts actually show
The C3S multi-system plume, released May 10, blends output from several dynamical forecast centers into percentile bands spanning the 10th through 90th levels, plus the full ensemble range. According to the C3S highlights page accompanying the release, the newest forecasts “strengthen the signal for El Niño development,” with more than 50 percent of ensemble members clearing the +2.5 degree Celsius mark in Niño 3.4.
That threshold carries weight. Only a handful of El Niño events since reliable ocean monitoring began have exceeded +2.5 degrees Celsius in Niño 3.4. The 1997-98 event, which triggered catastrophic flooding in Ecuador and Peru, drought-fueled wildfires across Indonesia, and coral bleaching from the Indian Ocean to the Caribbean, peaked near +2.4 degrees Celsius. The 2015-16 event reached roughly +2.6 degrees Celsius and contributed to global temperatures briefly crossing the 1.5 degree Celsius warming mark for the first time. A +3 degree Celsius anomaly would enter territory the modern observing network has never documented.
The +4.5 degree Celsius figure that has circulated in forecast discussions refers specifically to the Niño 1+2 index, not the broader Niño 3.4 box. Niño 1+2 tracks a smaller patch of ocean off Ecuador and northern Peru where anomalies routinely run higher than in the central Pacific during strong events. A +4.5 degree Celsius departure there and a +3 degree Celsius departure in Niño 3.4 can coexist during the same episode. Readers comparing headlines should note the geographic distinction, because the two numbers describe different parts of the ocean behaving consistently with a single, very powerful event.
Cross-checks from U.S. and international models
The European signal is not isolated. Experimental seasonal predictions from NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL), run through its SPEAR large-ensemble system, show warming trajectories in the equatorial Pacific that track in the same direction as the C3S output. The ENSO forecast plume maintained by Columbia University’s International Research Institute for Climate and Society (IRI), available through its current outlook page, also reflects strengthening warm anomalies across Niño sub-regions through late 2026.
These independent modeling lines matter because they reduce the chance that the European forecast is an artifact of a single model family’s biases. When dynamical systems built on different ocean-atmosphere codes, initialized with slightly different observational inputs, converge on the same broad outcome, forecasters treat the signal with higher confidence.
That said, the U.S. and European systems do not use identical category thresholds or reference periods. NOAA‘s Climate Prediction Center classifies El Niño intensity through its Oceanic Niño Index and related RONI strength probabilities, which use their own baseline and smoothing conventions. Direct comparison with C3S percentile bands requires careful alignment. Whether NOAA’s next coordinated update assigns the same probability to a “very strong” outcome as the European system remains an open question heading into the June forecast cycle.
Why the spread still matters
Even with more than half the C3S ensemble above +2.5 degrees Celsius, the gap between the 10th and 90th percentile bands is wide. The same forecast system that supports a super El Niño also contains ensemble members that peak well below that level. Seasonal forecasts are probabilistic by design: they describe a weighted range of plausible futures, not a single deterministic path.
The precise probability of reaching +3 degrees Celsius in Niño 3.4 or +4.5 degrees Celsius in Niño 1+2 has not been distilled into a single published number. The underlying ensemble-member time series are archived in the Copernicus Climate Data Store, but extracting a clean percentage from those datasets requires technical analysis that public-facing forecast summaries have not yet provided for this initialization.
Atmospheric wildcards add another layer of uncertainty. Ocean heat content in the equatorial Pacific sets the stage, but the Madden-Julian Oscillation and westerly wind bursts act as accelerators or brakes on the coupling between ocean warming and atmospheric response. The timing and strength of those triggers over June, July, and August will largely determine whether the upper tail or the lower tail of the forecast distribution wins out.
What a super El Niño would mean on the ground
The stakes extend far beyond ocean temperature charts. During the 1997-98 super El Niño, Peru suffered an estimated $3.5 billion in damage from flooding and mudslides. Indonesia and Australia endured severe drought, with Indonesian wildfires blanketing Southeast Asia in haze for months. Across the Horn of Africa, torrential rains triggered disease outbreaks. In the United States, California was battered by a relentless series of Pacific storms that caused widespread flooding and landslides.
The 2015-16 event followed a broadly similar playbook: drought in Australia and southern Africa, heavy rains along the South American coast, a suppressed Atlantic hurricane season, and amplified warmth across large parts of the globe.
A 2026 super El Niño would unfold against a backdrop that did not exist during those earlier events. Global baseline sea-surface temperatures have risen substantially over the past decade, meaning even moderate El Niño anomalies now sit on top of a warmer ocean. The result is that temperature records, coral bleaching thresholds, and marine heatwave benchmarks can be breached more easily. For agriculture, the combination of El Niño-driven rainfall shifts and already-stressed water systems in regions like southern Africa, South and Southeast Asia, and parts of South America raises the risk of compounding food security shocks.
Fisheries off Peru and Ecuador face a more immediate timeline. Warm water intrusions associated with strong El Niño events push anchovy populations deeper and farther south, disrupting one of the world’s most economically important fisheries. Peruvian authorities have historically imposed emergency catch limits during major events, and early signals from the Niño 1+2 region suggest those conversations may need to start soon.
What to watch in the weeks ahead
The next major decision point comes when NOAA’s Climate Prediction Center and the IRI release their updated ENSO diagnostics and probability tables in June 2026. Those products will reflect newer ocean observations and atmospheric data, and they will offer the clearest U.S.-based probability estimate for a very strong event.
On the observational side, weekly sea-surface temperature updates from NOAA’s OISST dataset and subsurface ocean heat content analyses from the Pacific Marine Environmental Laboratory will show whether the warm water volume along the equator is continuing to build or plateauing. A sustained increase in subsurface heat through June and July would be consistent with the upper-end forecast scenarios.
For now, the balance of evidence from European and international forecast systems points toward a high likelihood of at least a strong El Niño, with a meaningful chance the event reaches super-El-Niño territory. That is not a guarantee, but it is a strong enough signal that governments, agricultural planners, fisheries managers, and energy utilities with exposure to El Niño-driven disruptions should be stress-testing their contingency plans now rather than waiting for the next forecast update to confirm what the models are already suggesting.
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*This article was researched with the help of AI, with human editors creating the final content.
