The eastern Pacific Ocean is heating up faster than it did at the same point before either of the two most destructive El Niño events in modern history, and federal scientists now say the odds of a strong or very strong episode by autumn 2026 have climbed sharply since the start of the year. If the current trajectory holds, the resulting surge of ocean heat could push global temperatures past every annual peak in a record that stretches back to the mid-19th century, with consequences for farming, water supplies, wildfire risk, and disaster budgets across multiple continents.
The signal is already visible in the numbers. The Niño 3 sea-surface temperature index, maintained by NOAA’s Physical Sciences Laboratory using the ERSSTv5 dataset, is the standard yardstick researchers use to compare El Niño events across different decades. Through spring 2026, the index shows anomalous warming in the eastern equatorial Pacific that is running ahead of where the 1997 and 2015 super El Niños stood at the same developmental stage. Those two events went on to become the strongest on record in the modern observing era, each unleashing floods, droughts, and coral bleaching on a global scale.
A trajectory that echoes the most powerful events on record
“We are watching the tropical Pacific very closely because the rate of warming this spring has been unusually rapid,” said Michelle L’Heureux, lead of NOAA’s ENSO forecasting team, summarizing the tone of the agency’s recent outlooks. That urgency is reflected in the formal products. NOAA’s Climate Prediction Center set the stage in its ENSO Diagnostic Discussion issued April 9, 2026, formally raising the alert level. By May 2026, the CPC’s probability tables, calculated using its RONI-based methodology, placed the likelihood of a strong or very strong event during the autumn and early winter overlapping seasons above 50 percent. Separately, NOAA’s Geophysical Fluid Dynamics Laboratory published May 2026 predictions from its SPEAR ensemble forecast system, with the ensemble mean Niño 3.4 index tracking into strong El Niño territory (above +1.5 C anomaly) by the October-December season, while the full spread of individual runs ranged from moderate to very strong outcomes. Those model runs broadly reinforce the CPC outlook while flagging chaotic atmospheric variability as a key reason the forecast spread remains wide.
The shared message across these products: a strong event is now considerably more likely than it appeared earlier in the year, even though the precise peak intensity is still uncertain.
What makes the current buildup especially notable is the comparison to 1877. A 2020 study by Huang and colleagues, published in the Journal of Climate and archived in the NOAA Central Library, used ERSSTv5 ensemble analysis to reconstruct the peak Niño 3 value for the 1877-78 event, widely considered the strongest El Niño candidate in the instrumental record. Their central estimate placed the peak Niño 3 anomaly in the range of approximately +3 C, rivaling or exceeding the roughly +2.8 C peaks observed during 1997-98 and 2015-16, though the 19th-century confidence intervals were far wider. The researchers confirmed the event was exceptional but emphasized that those intervals widen dramatically when ship-based observations were sparse and unevenly distributed. Any claim that the current event will definitively surpass 1877-78 has to reckon with those error bars.
As of May 2026, the Niño 3 index was running at approximately +1.0 to +1.2 C above the long-term mean for the corresponding calendar month, compared with roughly +0.5 to +0.8 C at the same stage in the 1997 and 2015 buildup years according to the ERSSTv5 archive. That gap is what underpins the claim that the current event is “outpacing” its predecessors, though the margin is modest enough that a few weeks of shifting winds could close it.
Why the 1877 comparison matters and where it gets shaky
The reason analysts keep reaching back to 1877 is that the NOAAGlobalTemp record extends to 1850, providing the longest continuous surface temperature series from a U.S. federal agency. That baseline is what makes a direct comparison possible at all. But as NASA’s science team has noted in its GISTEMP FAQ, global observational coverage before 1880 was thin enough that precise year-to-year rankings carry substantially wider uncertainty than modern comparisons. The NOAAGlobalTemp series does cover the 1870s, but the confidence intervals for monthly values in that decade are far larger than for recent readings.
No single federal product currently draws a direct, quantified line from the present El Niño trajectory to a specific exceedance of the 1877-78 peak. The CPC assigns likelihood categories (weak, moderate, strong, very strong) rather than pinpoint index values, and the GFDL SPEAR runs do not include explicit peak Niño 3 thresholds tied to the 1877 uncertainty bounds established by Huang and colleagues. The leap from “higher likelihood of a strong event” to “record-shattering” involves an analytical step that the agencies themselves have not formally taken. That extrapolation belongs to outside analysts, not to official government statements.
The growth rate could still stall
El Niño development is not linear, and history offers a reminder of how differently these events can unfold. The 1997 event intensified explosively through the summer. The 2015 event built more gradually. Both peaked in the November-to-January window, but their paths diverged considerably between May and September. The current event could follow either trajectory or lose momentum entirely if trade wind patterns shift unexpectedly.
GFDL’s own documentation flags this directly: chaotic atmospheric variability during the summer months is a primary source of forecast uncertainty, meaning that even high-probability outlooks can be upended by a few weeks of anomalous wind behavior over the tropical Pacific. A 60 or 70 percent chance of a strong El Niño still leaves substantial room for a weaker peak.
On the global temperature side, the link between a powerful El Niño and record annual warmth is robust but not automatic. A strong event tends to add a short-lived heat boost on top of the long-term warming trend driven by greenhouse gas accumulation, but the size of that boost depends on how ocean and atmosphere patterns align over the full calendar year. Volcanic eruptions, aerosol loads, and shifts in other climate modes like the Indian Ocean Dipole can all modulate the final global average. “Very strong El Niño” and “warmest year on record” are closely related possibilities, not interchangeable guarantees.
What to watch for through the rest of 2026
The real-world stakes of a strong or very strong El Niño extend well beyond temperature rankings. Past super events reshaped weather patterns across entire hemispheres. The 1997-98 episode drove catastrophic flooding in Peru and Ecuador, severe drought across Indonesia and Australia, and an unusually active eastern Pacific hurricane season. The 2015-16 event contributed to widespread coral bleaching, crop failures in southern Africa, and a warm, wet winter across the southern United States that disrupted agricultural planning and strained flood infrastructure.
If the current event reaches comparable intensity, forecasters expect a similar menu of teleconnections: wetter conditions across the U.S. Gulf Coast and southern Plains, elevated drought risk in Australia and Southeast Asia, disrupted monsoon patterns in parts of South Asia, and warmer-than-normal winters across Canada and the northern United States. For agricultural markets, the timing matters enormously. A strong El Niño peaking in late 2026 would overlap with planting and harvest cycles in both hemispheres, potentially squeezing grain, coffee, and palm oil supplies simultaneously.
The observational picture will sharpen quickly. New monthly Niño 3 values and updated global temperature anomalies will either confirm that the event is maintaining its rapid pace or show that it has leveled off. Forecast centers, including the CPC, Australia’s Bureau of Meteorology, and the European Centre for Medium-Range Weather Forecasts, will refine their probabilities through the summer, narrowing the range of plausible peaks.
Where the evidence stands in June 2026
The most defensible reading of the data right now is this: a strong or very strong El Niño is increasingly likely, the current growth rate is outpacing the two most powerful modern analogs at the same developmental stage, and such an event would significantly raise the odds of record global warmth. But definitive rankings against 19th-century peaks will have to wait until the full observational record of this episode is complete. The ocean is moving fast. Whether it keeps accelerating or pulls back is the single most consequential climate question of the year.
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*This article was researched with the help of AI, with human editors creating the final content.
