The phrase is running in headlines again as the 2026 event strengthens. It is not a formal classification at either body checked here: WMO states plainly that it is not part of its operational system, and CPC’s published table uses very strong instead, with a number and a named index attached. This is what each body actually says, and why the number matters less than the index it is stated on.
“Super El Niño” is a useful piece of shorthand and a poor piece of terminology. It communicates big instantly, which is why it travels, and it carries no agreed number behind it, which is why two people using it may be applying different thresholds, indices or averaging periods.
That is not a complaint about journalists. It is a practical problem for anyone trying to work out whether this event is comparable to 1997-98, because the answer depends entirely on which scale the comparison is being made on. So here is what the agencies actually publish.
The World Meteorological Organization addressed this directly in its 31 July 2026 press release:
“WMO classifies ENSO events as weak, moderate, strong or very strong. The term ‘super El Niño’ is not part of WMO’s operational classification system and is therefore not used in official WMO products.”
That is about as unambiguous as agency language gets. Note what it does and does not say. It says the term is not used in WMO products. It does not say the term is meaningless, that nobody in the field uses it, or that events of that size do not happen.
One limitation worth stating plainly: WMO names its four categories in that release but does not publish the numeric thresholds behind them there, and I could not locate them in the other WMO sources I read. So this piece does not assign numbers to WMO’s categories. If you have seen thresholds attributed to WMO, it is worth checking where they actually came from.
NOAA’s Climate Prediction Center is more explicit, because its forecast product has to be. The Official ENSO Strength Probabilities table assigns a probability to each strength band across nine overlapping seasons, and it states its terms: the bands are labelled weak, moderate, strong and very strong, the probabilities are verified using the Relative Oceanic Niño Index, and anomalies are computed over the Niño-3.4 region against a 1991-2020 base period.
| Term | Band, three-month RONI | Who uses it | Official classification? |
|---|---|---|---|
| Weak | +0.5 to below +1.0°C | NOAA CPC | yes |
| Moderate | +1.0 to below +1.5°C | NOAA CPC | yes |
| Strong | +1.5 to below +2.0°C | NOAA CPC | yes |
| Very strong | +2.0°C and above, open-ended | NOAA CPC | yes, and the top band |
| “Historic” | RONI ≥ +2.5°C for OND 2026 | NOAA CPC, 13 Aug 2026 discussion | descriptive threshold used in the discussion; not a separate strength category, and it sits inside the very strong band |
| “Super” | no single agreed value | media, and some literature | no |
IAMElNino.com analysis, compiled from the CPC strength table and the 13 August 2026 Diagnostic Discussion. WMO’s four categories carry the same names as CPC’s but are left without numbers here for the reason given above.
The fifth row needs care, because it is easy to get backwards. CPC’s very strong category begins at +2.0°C RONI and has no upper limit. A +2.5°C event would therefore still be classified as very strong.
In its 13 August discussion, CPC added a more demanding threshold within that top category: a 69% probability that October-December RONI would reach +2.5°C or higher and exceed every previous event in the record beginning in 1950. CPC described that outcome as “historic,” but did not add a fifth category to its strength table.
That is why the 95% and the 69% are not competing numbers. The 95% is the probability of landing anywhere in the open-ended very strong band. The 69% is the probability of landing in a narrower region inside it. The table publishes the first and not the second, which is why the 69% appears only in the discussion narrative. We looked at what +2.5°C would actually have to beat earlier this week.
It also shows the useful thing about how CPC handled it. Faced with an outcome its standing categories do not distinguish, CPC did not reach for an informal label. It named a number and named the index the number is stated on. That is the whole difference between “historic” and “super.”
The problem with “super” is not that it has no definition anywhere. It is that it has several, and they are not commensurable.
One 2024 preprint, for example, constructs a bespoke Super El Niño Index and defines a Super El Niño as an SEI value of 80 or higher: a composite score, not a temperature at all. It is a preprint rather than established terminology, and is cited here only to show that competing definitions exist. Other usages in circulation are stated as a Niño 3.4 temperature threshold, and the values quoted differ between them.
I did not attempt to survey every definition in the literature, and this piece should not be read as a systematic review. The narrow point is enough: when a reader meets “super El Niño,” there is no single number they can look up to check it against, and at least one definition proposed in a publicly available preprint is not measured in degrees at all.
Here is the part that matters more than the label, and it is the reason this site exists.
Suppose two sources both use a “+2.0°C” bar. If one states it on the conventional Oceanic Niño Index and the other on the relative index, those are different bars. RONI subtracts the average anomaly of the global tropics before rescaling, so when Niño-3.4 warming is partly shared across the tropical oceans, it generally reads lower than the conventional index for the same ocean.
The current event makes the size of that gap concrete. For May to July 2026, CPC’s seasonal data files report a conventional ONI of +1.39°C and a RONI of +0.98°C for the same season: a difference of 0.41°C. IAMElNino.com calculation from the two CPC seasonal files, read unrounded and verified 13 August 2026.
Four tenths of a degree is most of the width of a strength band, since CPC’s bands are 0.5°C wide. In this particular May-to-July example the two values fall on opposite sides of CPC’s +1.0°C boundary, so the same season sits in a different descriptive band depending on which index you read. That will not always happen: the gap varies over time and a 0.41°C difference does not automatically move an event across a boundary. What is general is the point that a threshold quoted without its index cannot be checked. The difference between the two indices and why two agencies publish different numbers for the same week are set out in full elsewhere on this site.
None of this requires anyone to stop saying “super El Niño” in conversation. It requires one extra clause whenever a number is attached.
WMO states that “super El Niño” is not part of its operational classification and is not used in its official products. CPC’s published table uses weak, moderate, strong and very strong, with very strong meaning a three-month RONI value at or above +2.0°C. That top band is open-ended, so a +2.5°C event would still be very strong. When CPC wanted to distinguish the possibility of an unprecedented value within that open-ended category, it used “historic” and explicitly defined the additional +2.5°C RONI threshold, rather than borrowing “super.” The informal term is neither forbidden nor meaningless, but it is unofficial and inconsistently defined, and a threshold quoted without its index is not checkable at all.