Copernicus Records Second-Warmest September Globally

September 2026 was the second-warmest September in the global ERA5 record, with an average surface air temperature of 16.27°C. This was 0.82°C above the 1991–2020 average and 1.63°C above the estimated 1850–1900 pre-industrial average. The data are compiled by the Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts.

Global Temperature Records and Climate Baselines

ERA5 is a global atmospheric reanalysis dataset produced by the European Centre for Medium-Range Weather Forecasts. September 2026 was 0.11°C cooler than September 2023, the warmest September in the dataset. A monthly global temperature above 1.5°C relative to the pre-industrial baseline is distinct from the Paris Agreement’s long-term temperature goal, which concerns sustained warming over a longer period.

El Niño and Sea Surface Temperature

El Niño is the warm phase of the El Niño–Southern Oscillation, a recurring climate pattern involving changes in sea surface temperatures and atmospheric circulation across the tropical Pacific. The Niño 3.4 region is a central equatorial Pacific area used to monitor El Niño and La Niña conditions. Its September 2026 monthly sea surface temperature reached 29.70°C, a record for the region. El Niño conditions were strengthening and were expected to intensify further, potentially peaking later in 2026 and continuing into 2027.

For the extra-polar oceans between 60°S and 60°N, the September 2026 average sea surface temperature was 21.05°C, the highest for that month in the record. It exceeded the previous September record of 20.92°C, set in 2023.

Regional Temperature and Sea-Ice Conditions

Europe recorded its third-warmest September, with an average land temperature of 16.26°C, and experienced unusually warm and dry conditions. Antarctic sea ice reached its third-lowest annual winter maximum in September 2026. Sea-ice extent is the area of ocean where sea ice covers at least a specified proportion of the surface.

Important Facts for Exams

• The pre-industrial reference period used for the September 2026 temperature comparison was 1850–1900.
• The 1991–2020 period is the reference average used for the reported global surface air temperature anomaly.
• The previous September record for extra-polar sea surface temperature was set in 2023.
• The Paris Agreement was adopted in 2015 under the United Nations Framework Convention on Climate Change.

September 2026’s global surface air temperature was 16.27°C, while the extra-polar ocean sea surface temperature averaged 21.05°C. The Niño 3.4 region recorded a monthly sea surface temperature of 29.70°C.