The tropical Pacific is warming again, and two of the world’s most authoritative climate forecasting centers now agree: El Niño will probably arrive by midsummer and stick around through the end of 2026. If it does, the consequences will not stop at the calendar boundary. Because El Niño’s strongest push on global average temperatures typically lands in the year after the event matures, 2027 is shaping up as the likeliest candidate to shatter the all-time heat record set just two years ago.
Published in May 2026, this article draws on the latest operational forecasts and peer-reviewed research available at the time of writing.
The last time a powerful El Niño collided with steadily rising greenhouse-gas concentrations, the result was the hottest year in the modern measurement era. In 2024, global mean surface temperatures temporarily exceeded 1.5 degrees Celsius above pre-industrial levels for the first time in the annual record. That single-year exceedance is distinct from the Paris Agreement’s long-term threshold, which refers to warming sustained over multi-decadal averages rather than any individual year. Still, the breach underscored how close the climate system is operating to that critical guardrail. Now, with the Pacific poised to reload, scientists are watching closely to see whether the planet is about to repeat that sequence on an even higher baseline.
Two major forecasts point the same direction
NOAA’s Climate Prediction Center, in its April 2026 update, assigns a 61 percent probability of El Niño during the May-June-July season, with odds rising further into autumn. Columbia University’s International Research Institute for Climate and Society puts the figure even higher, reporting a 70 percent chance of El Niño developing in the April-through-June window and sustained elevated probabilities through the rest of the year.
The two centers rely on overlapping but distinct model ensembles, so their convergence carries more weight than either forecast alone. Both track sea surface temperature anomalies across the central and eastern equatorial Pacific. As of May 2026, ENSO-neutral conditions prevail following the end of the most recent La Niña, but both centers are signaling that the ocean has already begun shifting from that neutral state toward the warm phase characteristic of El Niño.
Why the 2023-24 precedent matters
The most recent El Niño, which peaked in late 2023 and carried into 2024, delivered a global temperature spike that surprised even seasoned climatologists. A peer-reviewed study published in Communications Earth and Environment found that the event produced an unusually large year-over-year warming jump. Using model-based decomposition, the researchers showed that changes in sea surface temperatures dominated the interannual signal and that the spatial pattern of Pacific warming was atypical, concentrating heat in regions that amplified the global average more than a textbook El Niño would.
That matters now because the baseline has not retreated. Global temperatures in early 2026 remain well above the long-term trend line, meaning any new El Niño will stack its warming on top of an already elevated starting point. The UK Met Office has published an explainer noting that strong El Niño events occurring against a warmer background can push temperatures to particularly extreme levels. The agency describes an approximate global-average warming contribution during El Niño years that, layered onto the long-term greenhouse-gas trend, compounds the risk of fresh records.
Because the peak influence on annual averages tends to appear in the calendar year after the event matures, a 2026 onset and late-year peak points directly at 2027 as the year most exposed to record-breaking heat.
What scientists still cannot pin down
Probability is not destiny, and several critical unknowns remain. No operational forecast or model ensemble cited in these sources has yet produced a specific projected global temperature anomaly for 2027. The NOAA and IRI probability tables describe the likelihood of El Niño conditions developing, not the magnitude of the event or its downstream temperature effect.
Strength is the biggest variable. A moderate El Niño adds measurably less heat to the global system than a strong one, and the gap between the two can determine whether a given year merely ties existing records or blows past them. The 2015-16 super El Niño, for instance, contributed to 2016 holding the annual heat record for nearly a decade.
Regional impacts are also unresolved. NOAA’s seasonal outlooks have not yet specified how this El Niño would reshape U.S. hurricane activity, western precipitation, or Asian monsoon patterns. Historical analogs suggest wetter winters across the southern United States and suppressed Atlantic hurricane formation, but each event distributes its energy differently depending on where Pacific warming concentrates. The atypical spatial pattern documented in the 2023-24 event is a reminder that composite averages from past El Niños are imperfect guides to the next one.
There is also the question of recurrence speed. This El Niño would arrive roughly two years after the last strong event, without a prolonged La Niña cooldown in between. Some researchers have raised the possibility that persistent warming of the equatorial Pacific could shorten the interval between El Niño events, but no peer-reviewed analysis published as of June 2026 confirms or quantifies that hypothesis. It remains an area of active investigation, not established science.
Why the window for uncertainty is narrowing fast
If El Niño develops as forecast and reaches moderate-to-strong intensity, the arithmetic is straightforward. The long-term warming trend driven by greenhouse gases continues to rise. El Niño adds a temporary but significant boost on top of that trend. And the lag between the Pacific event and its full expression in annual averages places the peak squarely in 2027.
Each of those premises rests on primary data: operational government forecasts, peer-reviewed research, and decades of observed ENSO behavior. The conclusion that 2027 could produce record-shattering warmth is a logical inference from their combination, not a guaranteed outcome. The event’s actual strength, its spatial pattern, and the behavior of other climate drivers like volcanic aerosols or Atlantic circulation patterns will all shape the final number.
But every month that Pacific sea surface temperatures continue to climb makes the El Niño forecast more robust and the implications for 2027 harder to dismiss. For communities already stretched thin by extreme heat, intensifying wildfires, and shifting rainfall patterns, the prospect of another record year is not an abstraction. It is a planning horizon.
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*This article was researched with the help of AI, with human editors creating the final content.
