Copernicus holds off calling El Niño the strongest after a record 29.70C reading in Nino3.4
Copernicus said Nino3.4 sea surface temperatures hit an all-time high of 29.70C in September, above the 1982/83, 1997/98 and 2015/16 peaks. Its newer index, which adjusts for warming of the tropical oceans, does not yet put the event above those three, so the record and the ranking come apart.
The Scientist · Science desk
Two bars for global average sea surface temperature in September: the previous high of 20.92C, set in 2023, and this September's record of 21.05C, according to Copernicus.
| Measure | Value | As of | Claim |
|---|---|---|---|
| Previous September high | 20.92 C | September 2023 | 9 |
| This September, a record | 21.05 C | 9 |
What happened
- Japan's weather agency said on Friday that El Niño conditions had reached their "strongest intensity on record", with temperatures in its monitoring area 4C above normal.
- Global average sea surface temperature hit a record 21.05C for September, topping the 20.92C set in the same month of 2023, according to Copernicus.
- The world had its second-hottest September on record, with surface air temperatures averaging 16.27C, the EU service said.
Why it matters
- contradiction Japan's agency calls the event the strongest on record while Copernicus declines to, so a "strongest ever" label depends on which scale the speaker used.
- constraint Any ranking against 1997/98 or 2015/16 is taken before the peak, and Copernicus's own wording leaves it open until the event has run its course.
- exposure Copernicus describes worldwide changes in winds, pressure and rainfall, so drought or flood exposure in any one region has to come from regional forecasts.
The record is an absolute temperature set against three older absolute temperatures [1][2]. That settles how warm the water was in September. It says less about how strong the event is, because the baseline under it has moved: according to AFP's report, climate change raises ocean temperatures and can make recent El Niño events appear stronger than past ones [4].
Copernicus responded with a new index that accounts for the warming of tropical oceans, and by that index the current event is not yet stronger than past ones [5]. In a statement to AFP it said it "cannot yet say that the current El Niño is the strongest ever recorded" [3]. It also said the September values "point to an already exceptionally strong El Niño, especially given that the event has not yet reached its peak" [6].
Both statements hold together. The first is a ranking against the past, and the adjusted index does not yet support it. The second describes the present. We think the 29.70C is the firmer finding, and the ranking stays open until the event peaks. Global forecasters have warned for months that this El Niño would likely become the strongest ever observed [13], and that remains a forecast. The thing this doesn't tell you is how far below the earlier events the adjusted index puts this one.
Japan's 4C above normal is a departure from a reference level, and Copernicus's 29.70C is an absolute reading [7][1]. The two figures sit on different axes, and AFP notes that forecasters do not all use the same scale [8].
The Pacific reading arrived in a month when global average sea surface temperature beat the previous September record by 0.13C [15]. Copernicus director Carlo Buontempo said in a statement: "We are in a new run of months above 1.5C, and with a strong El Niño still intensifying it is likely to last into 2027" [11]. He added: "Crossing the Paris Agreement's long-term limit is only a matter of time. How far we overshoot, and for how long, is still up to us" [12].
What to watch
- Whether Copernicus's adjusted index puts this El Niño above the 1982/83, 1997/98 and 2015/16 events once the peak has passed.
- Whether the run of months above 1.5C extends into 2027, as Copernicus director Carlo Buontempo expects.
- Whether Copernicus's monthly updates keep global sea surface temperature above the 2023 records as El Niño intensifies.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence72
- Adoption
- Insufficient
- Hype gap+15
- Incentives
- Insufficient
- Confidence70
Perspective Coverage
5 publishers- Builder
- Builder 6%
- Operator
- Operator 58%
- Investor
- Investor 36%
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The Copernicus Climate Change Service said sea surface temperatures in the Nino3.4 El Niño monitoring region of the Pacific reached an "all-time high" of 29.70C in September.
- [2]
The September Nino3.4 reading exceeded the peak temperatures of the previously strong El Niño events of 1982/1983, 1997/1998 and 2015/2016.
- [3]
Copernicus said in a statement to AFP that it "cannot yet say that the current El Niño is the strongest ever recorded".
- [4]
As climate change raises ocean temperatures, it can make recent El Niño events appear stronger than past ones, complicating historical comparisons.
- [5]
Copernicus said it had adopted a new index, which accounts for the warming of tropical oceans, that suggested the current event is not yet stronger than past ones.
- [6]
Copernicus told AFP that the values observed in September "point to an already exceptionally strong El Niño, especially given that the event has not yet reached its peak".
- [7]
On Friday, Japan's weather agency said that El Niño conditions had reached their "strongest intensity on record", with temperatures in the phenomenon's monitoring area 4C above normal.
- [8]
Not all forecasters use the same scale to interpret El Niño.
- [9]
Global average sea surface temperatures hit a record 21.05C for September, topping the previous high of 20.92C for the same month in 2023, according to Copernicus.
- [10]
The world experienced its second-hottest September on record, with surface air temperatures averaging 16.27C, the EU service said.
- [11]
"We are in a new run of months above 1.5C, and with a strong El Niño still intensifying it is likely to last into 2027," Copernicus director Carlo Buontempo said in a statement.
- [12]
"Crossing the Paris Agreement's long-term limit is only a matter of time. How far we overshoot, and for how long, is still up to us," Buontempo said.
- [13]
Global forecasters have been warning for months that this El Niño would likely become the strongest ever observed.
- [14]
El Niño warms surface temperatures in the central and eastern equatorial Pacific Ocean, bringing worldwide changes in winds, pressure and rainfall patterns.
- [15]
The September 2026 global average sea surface temperature record beat the 2023 September record by 0.13C.
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Sources
2 independent publishers whose own reporting we read for this story.
- El Nino sets temperature record in key Pacific zone: EU monitor | AFP.com
afp.com
1 article · October 11, 2026
- channelnewsasia.comEl Nino sets temperature record in key Pacific zone: EU monitor - CNA
1 article · October 11, 2026
- economictimes.indiatimes.comEl Nino pushes Pacific to its hottest ever, and global temperatures show no sign of cooling - The Economic Times
1 article · October 11, 2026
- phys.orgEl Niño sets temperature record in key Pacific zone: EU monitor
1 article · October 12, 2026
- straitstimes.comEl Nino sets temperature record in key Pacific zone: EU monitor
1 article · October 11, 2026
Topics and entities
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Topics
Entities
- Nino3.4 regionFollow
- Carlo BuontempoFollow
- Japan Meteorological AgencyFollow
- Agence France-PresseFollow
- World Meteorological OrganizationFollow
- Copernicus Climate Change ServiceFollow