Warmest October on Record 2026 Puts the Year on Course to Exceed 1.5°C

The warmest October on record 2026 is now a measured fact, not a forecast. October averaged 15.35°C globally, 0.90°C above the 1991–2020 average and 1.75°C above the estimated 1850–1900 pre-industrial level, according to ERA5 data published by the Copernicus Climate Change Service on 6 November 2026 (Copernicus). Information verified through 8 November 2026.

It was the third consecutive month above 1.5°C. The previous run of at least three such months ended in April 2025 (Copernicus).

Warmest October on record 2026 and the 2026 exceed 1.5C above pre-industrial levels outlook

Copernicus says the full year is now virtually certain to finish above 1.5°C. In its statistical model, “virtually certain” means a probability of more than 99%, with a predicted range of 1.56°C to 1.61°C (Copernicus). That would make 2026 only the second calendar year above that level, after 2024 (Reuters via Duke FM).

The service puts the chance of 2026 ranking as the second-warmest year on record at about 80%, with a 20% chance of tying or exceeding 2024, currently the warmest year on record (Copernicus).

A single year above 1.5°C does not by itself breach the Paris Agreement goal, which refers to a long-term average (Reuters via Duke FM). The longer view is catching up with the goal anyway. Copernicus expects the four-year average for 2023–2026 to exceed 1.5°C as well (Copernicus).

Samantha Burgess, Strategic Lead for Climate at the European Centre for Medium-Range Weather Forecasts, put it this way: “October has continued the pattern of remarkable global warmth, with record global and surface ocean temperatures. 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” (Copernicus).

El Niño record sea surface temperature October 2026 in the Pacific

The oceans did much of this work. 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 (Copernicus).

In the tropical Pacific, where El Niño conditions continued to intensify, the monthly sea surface temperature anomaly in the Niño 3.4 region reached an all-time high, exceeding the peaks recorded during previous very strong El Niño events (Copernicus). The Weather Network reported waters in that key region running more than 3°C above normal, an all-time high for this time of year (The Weather Network).

El Niño is not the whole story. The underlying baseline has moved. Data from Copernicus indicate the world has not recorded a below-average October since 2007 (The Weather Network). A natural cycle can push a warm planet to a record. It struggles to explain a run of Octobers that never dip below average at all.

A warm month, felt unevenly on the ground

Europe’s October was its second warmest on record. The average temperature over European land was 1.49°C above the 1991–2020 average, behind only 2022, with the largest warm anomalies in eastern Europe and Scandinavia while western and central Europe saw smaller ones (Copernicus; Meteorological Technology International).

Heat came with a split hydrological picture. Exceptionally low river flows persisted across much of central and eastern Europe, affecting the Rhine, Danube and Vistula, while heavy rainfall and flooding affected the UK and Ireland, Spain, Greece and Türkiye (Copernicus). Dry in one basin, flooded in the next — in the same month, on the same continent.

Sea ice told a quieter version of the same story. Arctic sea ice extent was about 9% below average in October, and Antarctic extent was also about 9% below average, ranking second lowest for the month in the satellite record behind only 2023 (Copernicus).

These bulletin figures come with an honest caveat, and Copernicus states it itself: predictions based on other temperature datasets, statistical models or periods of available data may give different probabilities for the year’s final ranking (Copernicus). The October measurement itself, drawn from the ERA5 reanalysis, is not presented as uncertain in the same way.

Analysis: the headline number will be 1.5°C, and it will be argued over as a threshold. The more telling figure in this bulletin is the four-year average. A hot October can be blamed on El Niño. A hot summer can be blamed on a season. Four years averaging above a level the world set as a limit is harder to file under weather. Delegates arriving in Antalya for COP31 from 9 November will negotiate against that backdrop — not a projection of a warmer future, but a service reporting, month by month, that the warmer period has already lasted long enough to average out.

Photo: Rosser1954, via Wikimedia Commons (CC BY-SA 4.0)

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