September 2026 Second-Warmest on Record as Global Temperatures Stay Above 1.5°C: Copernicus

Key facts

• September 2026 was the second-warmest September ever recorded globally, with the global-average surface air temperature at 16.27°C, 0.82°C above the 1991–2020 average and 0.11°C cooler than September 2023, according to the Copernicus Climate Change Service (C3S).
• Global temperatures in September 2026 were 1.63°C above the estimated pre-industrial 1850–1900 average, marking the second consecutive month above 1.5°C after August 2026, in a run expected to continue into 2027.
• The average sea surface temperature for extra-polar oceans (60°S–60°N) in September 2026 was the highest on record for the month at 21.05°C, surpassing the previous September record of 20.92°C set in 2023.
• The monthly sea surface temperature in the Niño 3.4 region reached an all-time high of 29.70°C, exceeding peaks of the strong El Niño events of 1982/1983, 1997/1998 and 2015/2016.
• September 2026 was the third-warmest September for Europe as a whole at 16.26°C (1.54°C above the 1991–2020 average), while western Europe recorded its joint-warmest September, tied with September 2023 at 2.51°C above average.
• Record-low September river flows occurred in parts of the Rhine, Danube, Vistula and Garonne-Dordogne, disrupting navigation, water supply and agriculture in several countries.
• Arctic sea ice reached its annual summer minimum, the 14th-lowest in the satellite record, while around Antarctica the daily sea ice extent reached its annual winter maximum, the third-lowest in the satellite record at about 6% below average.
• The World Meteorological Organization (WMO) said on October 8 that El Niño will continue to intensify and is likely to peak in December, bringing above-average temperatures and shifting rainfall patterns.