September 2026 was the world’s second-warmest September on record, with global temperatures reaching 1.63°C above pre-industrial levels for the second consecutive month, according to data released by the European Union’s Copernicus Climate Change Service on Monday.
The global average temperature reached 16.27°C, standing 0.82°C above the September average for the 1991-2020 reference period. Only September 2023 was warmer, exceeding September 2026’s average by 0.11°C.
The findings highlight the persistence of unusually high global temperatures and renewed concerns about the pace of climate change. September marked the first time since November 2025 that global temperatures had remained above the 1.5°C threshold for two consecutive months. Scientists expect the period of elevated temperatures, which began in August, to continue into 2027 as El Niño conditions strengthen.
“September was the second warmest on record globally, with exceptionally high temperatures experienced again across parts of Europe after an extreme summer,” said Carlo Buontempo, director of the Copernicus Climate Change Service.
Buontempo also warned that the world was approaching the point at which long-term global warming could exceed the 1.5°C limit established under the Paris Agreement. However, temperatures exceeding that threshold in individual months do not, by themselves, mean that the agreement’s long-term warming target has been breached.
The Finnish Meteorological Institute said repeated monthly temperature increases above 1.5°C indicate that the world is moving closer to that long-term level of warming. Researcher Mika Rantanen said current estimates suggest the threshold could be reached on a more sustained basis towards the end of the decade.
Europe recorded its third-warmest September, with an average temperature of 16.26°C, or 1.54°C above the 1991-2020 average. Western Europe experienced its joint-warmest September, matching the 2023 record at 2.51°C above average. The region had already recorded its warmest summer.
Finland also experienced warmer-than-usual conditions. According to the Finnish Meteorological Institute, temperatures across much of the country were between 1°C and 1.5°C above the 1991-2020 average. The figures place Finland among the areas affected by the broader pattern of unusually warm conditions across Europe.
The heat coincided with drought across western, central and parts of eastern Europe, putting pressure on waterways, agriculture and water supplies. Sections of the Rhine, Danube, Vistula and Garonne-Dordogne river systems recorded their lowest September flows on record, disrupting shipping and adding to difficulties for water-dependent industries.
Dry conditions intensified in parts of Spain, Portugal, France, Italy, the western Balkans and Greece. Rainfall towards the end of September eased conditions in some areas, but it also triggered flooding in parts of France and Spain, illustrating the contrasting effects of prolonged dry weather and periods of intense rainfall.
The warming extended beyond land. Average sea surface temperatures outside the polar regions reached 21.05°C in September, the highest level recorded for the month. The figure surpassed the previous September record of 20.92°C, set in 2023.
Temperatures in the tropical Pacific also drew attention. The Niño 3.4 monitoring region reached 29.70°C, exceeding previous peaks associated with major El Niño events. El Niño is a natural climate phenomenon involving unusually warm ocean temperatures in the central and eastern tropical Pacific. It can influence weather patterns around the world and contribute to higher global average temperatures.
The polar regions also recorded below-average sea ice levels. Antarctic sea ice reached its third-lowest winter maximum in the satellite record, while the September monthly extent was approximately 6% below average.
In the Arctic, sea ice reached its annual summer minimum, ranking 14th lowest in the satellite record. Its monthly extent was approximately 10% below average.
Taken together, the September figures show that unusually high temperatures are affecting the atmosphere, oceans and polar regions, while parts of Europe continue to face the combined pressures of heat, drought and flooding. Although a single month’s temperature cannot establish whether the Paris Agreement’s long-term limit has been crossed, the repeated exceedances underline the growing importance of tracking sustained global warming.
