October 2026 was the warmest October ever recorded, the European Union's Copernicus Climate Change Service said on Friday, and 2026 is now virtually certain to become only the second calendar year — after 2024 — to finish more than 1.5°C above pre-industrial levels. The announcement lands three days before world leaders gather in Antalya, Türkiye, for the COP31 climate summit, where the gap between pledges and temperatures will be the central argument.
According to Copernicus, the global average surface air temperature in October was 15.35°C — 0.90°C above the 1991–2020 average and 1.75°C above the estimated 1850–1900 pre-industrial average. It was the third month in a row to sit above 1.5°C, after August and September. The last run of at least three consecutive months above the threshold ended in April 2025.
Based on temperature data recorded up to October, Copernicus estimates that the annual global average temperature for 2026 will most likely land between 1.56°C and 1.61°C above pre-industrial levels. That makes 2026 most likely the second-warmest year on record, with about an 80 per cent chance of that ranking — and about a 20 per cent chance of tying or even exceeding 2024, currently the warmest year on record.
What the October data shows
The figures come from ERA5, the Copernicus reanalysis dataset that combines satellite observations, weather stations and other measurements. Copernicus describes the 2026 outcome as "virtually certain" — a probability of more than 99 per cent under its statistical model. The service notes that predictions based on other temperature datasets, statistical models or periods of available data may give different probabilities.
| Measure | October 2026 | What it means |
|---|---|---|
| Global surface air temperature | 15.35°C | Warmest October on record; 0.90°C above the 1991–2020 average |
| Above pre-industrial levels | 1.75°C | Third consecutive month above 1.5°C |
| 2026 annual average (predicted) | 1.56–1.61°C above pre-industrial | Virtually certain to exceed 1.5°C for the year |
| Sea surface temperature (outside polar regions) | 20.95°C | Highest October on record, beating October 2023 |
| Niño 3.4 sea surface anomaly | 3.21°C | All-time high, above the peaks of 1982–83, 1997–98 and 2015–16 |
| Europe (land average) | 11.51°C | Second-warmest October on record, behind 2022 |
The oceans told the same story. The average sea surface temperature outside the polar regions reached 20.95°C in October, the highest on record for the month, surpassing the previous October record set in 2023. In the tropical Pacific, where El Niño conditions continued to intensify, the monthly sea surface temperature in the Niño 3.4 region reached an all-time high of 29.94°C, with a record anomaly of 3.21°C — above the peaks recorded during the previous very strong El Niño events of 1982–1983, 1997–1998 and 2015–2016.
Why the four-year figure matters. Copernicus also expects the four-year average global temperature for 2023–2026 to exceed 1.5°C above pre-industrial levels. A single hot year can be driven by a strong El Niño; a four-year average above the threshold points to sustained warmth, not a one-off spike.
An exceptionally strong El Niño
El Niño — the periodic warming of the eastern and central tropical Pacific — is adding heat on top of the long-term warming driven by human activity. Copernicus says the current event is exceptionally strong and is expected to peak towards the end of the year.
"October has continued the pattern of remarkable global warmth, with record global and surface ocean temperatures," said Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts, which operates Copernicus. "An exceptionally strong El Niño is adding further heat to a climate already warmed by human activities, while 2026 is on track to become the second calendar year above 1.5°C."
"Particularly significant is that the four-year average is also expected to exceed 1.5°C, highlighting how sustained this period of global warmth has become." — Samantha Burgess, strategic lead for climate, ECMWF
The pattern is not uniform. Europe recorded its second-warmest October, at 11.51°C — 1.49°C above the 1991–2020 average, behind only 2022. Temperatures were most above average in eastern Europe and Scandinavia, while much of western and central Europe saw smaller warm anomalies, and parts of the southern Balkans, Greece, the eastern Mediterranean and western Türkiye were cooler than average.
October also brought sharply contrasting conditions across the continent: exceptionally low river flows persisted across much of central and eastern Europe, affecting the Rhine, Danube and Vistula, while heavy rainfall and flooding hit the UK and Ireland, Spain, Greece and Türkiye. Outside Europe, drier-than-average conditions covered much of eastern North America, the southern United States, western Russia, parts of Siberia and central Asia, southern China, parts of South America and southern Africa — while Alaska, parts of the southern USA and northern Mexico, central Asia, parts of China and Korea, Chile, southern Argentina, southeastern Brazil, southernmost Africa, Madagascar and western and central Australia were wetter than average.
Sea ice, meanwhile, stayed well below average in both polar regions. Arctic sea ice extent was about 9 per cent below average in October, ranking 13th lowest for the month in the 48-year satellite record, with sea ice in the Kara Sea at a record low for October. Antarctic sea ice extent was also about 9 per cent below average, the second lowest for the month in the satellite record, behind only 2023.
What 1.5°C does — and does not — mean
The 1.5°C figure is the central target of the 2015 Paris Agreement, under which countries agreed to try to limit global warming to 1.5°C above pre-industrial levels. But the target refers to a long-term average, so a single calendar year above the mark does not mean it has been breached. What the Copernicus data shows is that the world is now spending whole years — and, on current evidence, a whole four-year stretch — above a level once treated as a guardrail for the decades ahead.
What is not yet settled. The 2026 annual figure is a statistical prediction based on ERA5 data up to October, not a measured full-year result; the final ranking will depend on November and December data and may differ across datasets. The "virtually certain" wording reflects a probability of more than 99 per cent under Copernicus's model — other datasets and models may give different probabilities.
Why it matters now
The timing is pointed. COP31, the UN climate summit, opens on Monday in Antalya, Türkiye, with negotiators facing a familiar question: what, if anything, can still close the gap between current pledges and the temperatures now being recorded. The last summit cycle was dominated by arguments over finance for loss and damage and the pace of the shift away from fossil fuels; the October data gives both sides fresh numbers to argue with.
The record also complicates the politics of adaptation. October's flooding in parts of Europe and the persistent low river flows in the continent's east arrived in the same month — a reminder that a warming climate does not produce one kind of extreme, but several at once, in different places, in the same season.
Frequently asked questions
Was October 2026 really the hottest October ever recorded?
Yes, according to the Copernicus Climate Change Service, using its ERA5 dataset. The global average surface air temperature was 15.35°C, 1.75°C above the estimated 1850–1900 pre-industrial average — the warmest October in the record.
Does 2026 passing 1.5°C mean the Paris Agreement target has failed?
No — not in the formal sense. The Paris target refers to a long-term average, so a single year above 1.5°C does not breach it. But Copernicus expects the four-year average for 2023–2026 to exceed 1.5°C as well, which shows how sustained the warmth has become.
How much of this is El Niño, and how much is climate change?
Both. Copernicus attributes the record in part to an exceptionally strong El Niño, which is adding heat to a climate already warmed by human activities. El Niño is temporary and expected to peak towards the end of the year; the underlying warming trend is not.
How certain is the 2026 forecast?
Copernicus calls it "virtually certain" — more than 99 per cent probability under its statistical model, based on data up to October. The predicted annual range is 1.56–1.61°C above pre-industrial levels. Other datasets and models may give slightly different probabilities.
What happens next?
November and December data will fix 2026's final ranking — most likely second-warmest on record, with about a 20 per cent chance of matching or beating 2024. COP31 opens on Monday in Antalya, where the October figures will frame the negotiations.
Key takeaways
- October 2026 was the warmest October on record: 15.35°C globally, 1.75°C above pre-industrial levels.
- It was the third consecutive month above 1.5°C — August, September and October.
- 2026 is virtually certain to finish above 1.5°C for the year, the second calendar year to do so after 2024.
- Ocean temperatures also set October records, driven by an exceptionally strong El Niño whose Niño 3.4 anomaly hit an all-time high of 3.21°C.
- The four-year average for 2023–2026 is also expected to exceed 1.5°C — a sign of sustained, not one-off, warmth.
The numbers will be updated as November data arrives, and the final ranking for 2026 will not be settled until early next year. What is already clear is that the world has now spent three straight months, and almost certainly a full second year, above the threshold it once promised itself it would not cross. The question for COP31 is what, if anything, changes because of it.
