About That “Super El Niño”

On Thursday, May 14, the NOAA Climate Prediction Center issued its monthly ENSO Diagnostic Discussion. Within hours, CNN ran a piece under the headline:

A Super El Niño is coming. Here’s how a hotter ocean could change the weather near you.

The piece opens by telling readers that El Niño is “emerging even faster than expected in the Pacific Ocean and odds are increasing that it could become historically strong, a rare ‘Super’ El Niño, by fall or winter.”

That framing is worth examining, because it does not appear in the NOAA discussion the article is built on.

What the forecast actually says

The May 8 ENSO Diagnostic Discussion is direct about current conditions:

ENSO-neutral conditions are present. Equatorial sea surface temperatures (SSTs) are near-to-above-average across the central and eastern Pacific Ocean. El Niño is likely to emerge soon (82% chance in May-July 2026) and continue through Northern Hemisphere winter 2026-27 (96% chance in December 2026 – February 2027).

The El Niño Watch is real. The probability of an El Niño appearing this summer is high. The probability of one persisting into winter is very high. None of that is in dispute.

What gets less attention is what comes next. The CPC’s probabilistic strength forecast assigns roughly a 2-in-3 chance that the November–January 2026-27 peak will be classified as “strong or very strong.” It assigns roughly a 1-in-3 chance that the event peaks as a Super El Niño, defined as a Niño-3.4 relative SST anomaly exceeding 2.0°C.

A 1-in-3 chance, as a matter of statistics, is what one would more commonly describe as “unlikely.” Coin-flip outcomes do not normally get headlines reading “Heads is coming.” The increment from last month’s 1-in-4 probability, a single CPC update earlier, has nonetheless been packaged as a developing trend toward something “historically strong.”

The forecaster running the desk is more measured. Michelle L’Heureux, who leads El Niño and La Niña forecasting at the Climate Prediction Center, told ABC News:

There is substantial uncertainty in the ultimate strength of El Niño. While there is a 2-in-3 chance of a strong or very strong El Niño for the November-January 2026-27 season, there is still a 1-in-3 chance of an event weaker than that.

The CPC’s own update is similarly careful:

Stronger El Niño events do not ensure strong impacts; they can only make certain impacts more likely.

The conditions that have to line up

For a Super El Niño to develop, two systems have to remain in phase. The tropical Pacific upper-ocean heat content has to stay elevated, and the atmospheric circulation has to respond in a way that reinforces the oceanic anomaly rather than damping it.

The current subsurface signal is favorable. Per the CPC’s evolution status document, “negative subsurface temperature anomalies emerged in mid-July 2025 and persisted through mid-December 2025. From mid-December 2025 through late April 2026, positive anomalies developed and gradually increased.” The upper-ocean heat content anomaly is now above average and the thermocline slope index is below average, both consistent with the early stages of a warm event.

The atmospheric piece is the open question. L’Heureux explained the requirement to ABC News:

El Niño depends on the tropical Pacific ocean and atmosphere interacting in a way that reinforces the event. For example, we need to see weaker than average trade winds along the equatorial Pacific Ocean because that will help keep the ocean surface temperatures above average.

That coupling is what separates the strong events from the merely warm ones. The strongest El Niños in the historical record are characterized by sustained ocean-atmosphere coupling through the summer, and whether that coupling materializes this year is what the spring forecast cannot yet resolve.

The spring predictability barrier

ENSO forecasters have a name for the uncertainty L’Heureux is describing. It is called the spring predictability barrier, and it refers to the well-documented tendency for ENSO forecasts issued in boreal spring to perform worse than forecasts issued at other times of year. The tropical Pacific in late spring and early summer sits at a transition point where the coupled ocean-atmosphere system is most sensitive to initial conditions, and forecast skill collapses accordingly.

This is not a quibble from skeptics. The World Meteorological Organization, in its most recent Global Seasonal Climate Update, states the issue plainly:

Models indicate that this may be a strong event, but the so-called spring predictability barrier is a challenge for the certainty of forecasts at this time of year.

The WMO is even more cautious about the upper bound:

While some model forecasts indicate the possibility of stronger conditions later in the year, there is currently no consensus or sufficient confidence to confirm or exclude a high-intensity event.

That is the operating expert community describing a forecast that the press is presenting as a near-certainty.

The buried admission

Among the more striking numbers in the current forecast cycle is one that has not received much coverage. The same NOAA office that issued the El Niño Watch, NOAA’s National Centers for Environmental Information, has also issued its outlook for 2026 global temperature rankings.

According to that outlook, there is a 96% probability that 2026 ranks among the five warmest years in the instrumental record.

There is a less than 1% probability that 2026 sets a new record.

That admission deserves a moment. After three years in which “warmest year on record” headlines have followed every January with metronomic regularity, the agency that produces those rankings has now publicly assessed that even with a developing El Niño, even with a 2-in-3 chance of a strong or very strong event, 2026 has effectively no chance of beating the recent peak.

The implication is straightforward. The 2023–2024 spike, the one attributed at the time to everything from anthropogenic forcing to the Hunga Tonga eruption to the IMO 2020 reduction in marine sulfate emissions, has subsided. NCEI now puts the probability of clearing it this year at less than 1%, and the probability of clearing it next year depends entirely on whether the developing El Niño manages to peak in the upper portion of its forecast distribution.

This is the kind of quiet methodological update that ought to inform public framing of climate trends. Instead, it sits under a 96% top-five-warmest headline that obscures the more interesting structural detail.

The 2015-16 precedent

Comparison to the last Super El Niño is worth doing carefully. The 2015–16 event was, in NOAA’s records dating to 1950, the strongest El Niño ever observed. It cleared the 2.0°C Niño-3.4 threshold and remained there for an extended period. By every standard objective metric it was, in fact, super.

The CNN article concedes that even a super event’s predicted impacts do not necessarily materialize:

The 2015-2016 Super El Niño delivered on its reputation of causing serious drought in the Caribbean, but also failed to produce the wetter than average winter it’s known for in Southern California.

Southern California’s expected El Niño response, wetter winters, replenished reservoirs, drought relief, is the canonical impact in the popular imagination. The 2015–16 event was the largest El Niño on record. It failed to produce that response.

The CPC’s standard caveat, that strong events make certain impacts “more likely” but do not ensure them, is doing a lot of work here. In the most extreme observed case, in the region with the most widely publicized expected impact, the relationship did not hold. That is the kind of empirical result that should temper confident projections about what a possibly-Super-and-probably-not El Niño will do to weather patterns nine to twelve months out.

One technical change is worth flagging because it affects how this event will be compared to its predecessors. In February 2026, NOAA moved to a relative ONI methodology, in which the Niño-3.4 SST anomaly is computed as the departure from the tropical-mean SST rather than from a fixed climatological base period. The relative index is then rescaled to match the variance of the traditional index.

The motivation is reasonable: with the entire tropics warming, the older absolute-anomaly approach was producing El Niño classifications during periods when the equatorial Pacific was not, in fact, anomalously warm relative to the surrounding ocean. The relative index isolates the actual ENSO signal more cleanly.

The practical effect is that direct comparisons between the 2015–16 event under the old methodology and a possible 2026–27 event under the new methodology require some care. A “Super” classification today is not measuring exactly the same quantity it measured a decade ago. This is a defensible scientific update, but it is worth noting whenever the “strongest on record” framing is invoked.

None of this is to suggest that there is no El Niño developing, or that NOAA’s forecasters are wrong about the probabilities they are publishing. The CPC’s discussions are careful, the probability ranges are reasonable, and the model agreement on emergence by mid-year is broad and consistent.

The issue is the translation layer.

The forecast says: 82% chance of El Niño emerging by July, 96% chance of persistence into winter, 2-in-3 chance of peaking strong or very strong, 1-in-3 chance of clearing the Super threshold, substantial uncertainty in ultimate strength, spring predictability barrier limiting confidence, no expert consensus on high-intensity scenarios, and a less than 1% chance that 2026 sets a new annual temperature record.

The coverage says: “A Super El Niño is coming.”

These are not the same statement. One is a probability distribution with explicit uncertainty bounds drawn by the forecaster running the desk. The other is a declarative claim about a specific outcome at the upper tail of that distribution.

The CPC has done the responsible thing by publishing the underlying probabilities, by quoting its own scientist’s uncertainty caveats, and by including the standard reminder that impacts do not follow mechanically from category. The next ENSO Diagnostic Discussion is scheduled for June 11. By then the spring predictability barrier will have started to dissolve, and the probability ranges will tighten. Whether they tighten upward toward a Super event or downward toward a routine moderate one is, at this point, genuinely unknown.

In the meantime, “could become historically strong” is what the forecast actually allows. “Is coming” is what the headline says.