September 2025 recorded average global surface air temperatures at 0.66°C above the 1991–2020 average, making it the third-warmest September on record, new data from the Copernicus Climate Change Service (C3S) has revealed.
The average ERA5 surface air temperature globally stood at 16.11°C for the month, with this September 0.27°C cooler than the warmest on record, in 2023. It was 0.07°C cooler than September 2024.
September 2025 was also 1.47°C above the estimated 1850-1900 average used to define pre-industrial levels, while the 12-month average temperature between October 2024 and September 2025 was 1.51°C above pre-industrial levels.
Global temperature context
“The global temperature in September 2025 was the third warmest on record, nearly as high as in September 2024, less than a tenth of a degree cooler,” commented Samantha Burgess, strategic lead for climate, C3S.
“A year on, the global temperature context remains much the same, with persistently high land and sea surface temperatures reflecting the continuing influence of greenhouse gas accumulation in the atmosphere.”
Across Europe, the average temperature for September stood at 15.95°, which was 1.23°C above the 1991–2020 average, making it the fifth-highest September on record. The most pronounced above-average temperatures were recorded in Fennoscandia and eastern Europe, while cooler-than-average temperatures were seen in certain parts of Western Europe.
Beyond Europe, above-average temperatures were recorded in Canada, parts of Greenland, northwestern Siberia, and parts of Antarctica.
Global sea surface temperatures were also at their third-highest on record in September, C3S noted, with the average sea surface temperature for September standing at 20.72°C. This was 0.20°C below the September 2023 record.
Sea-surface temperatures
Above-average sea-surface temperatures were recorded in much of the North Pacific, with some areas experiencing a record high. In Europe, record-high sea-surface temperatures were recorded in a large area from the Norwegian Sea to the Kara Sea, while the Mediterranean was largely above-average.
Precipitation patterns across Europe were mixed in September, with wetter-than-average conditions in Northwestern and Central Europe, as well as Fennoscandia, along the eastern Black Sea coast, parts of Italy, and coastal regions of Croatia and eastern Spain. Most of the Iberian Peninsula, along with the Norwegian coast, much of peninsular Italy, the Balkans, and parts of Ukraine and western Russia, were drier than normal.
Outside Europe, wetter-than-average conditions occurred across parts of the Americas, Africa, and Asia, while some areas of Canada, the eastern United States, and northeastern Mexico saw below-average rainfall. Read more here.
