September 2026, second-hottest month ever recorded on Earth

The European Copernicus Climate Change Service has certified that September 2026 was the second-hottest September ever recorded on Earth, surpassed only by September 2023. The anomaly recorded is +1.63°C compared to pre-industrial levels, the reference threshold the service uses to compare current temperatures with the period before industrialisation.

The figure is part of a sequence that also includes August 2026: both months exceeded the 1.5°C anomaly threshold, a condition that according to the bulletin had not occurred since November 2025. Copernicus notes that the sequence could continue into 2027, should the El Niño climate phenomenon strengthen.

At regional level, western Europe recorded for September an anomaly of +2.51°C compared to the pre-industrial period, the highest value ever measured for this month in the area. The bulletin also notes that the world’s oceans reached a record average surface temperature, while Europe had to contend with an anomalous heatwave and a drought that reduced the flow of the continent’s major rivers to historic lows.

The director of the Copernicus Climate Change Service, Carlo Buontempo, attributed the anomaly to the ongoing phenomenon: “It’s El Niño’s fault. And in 2027 it will get worse.”

This is a monthly bulletin, which measures the anomaly of a single month compared to the pre-industrial reference period and does not in itself constitute a long-term projection: any continuation of the sequence beyond the 1.5°C threshold in 2027, indicated by the service as possible based on the strengthening of El Niño, remains an assessment tied to the evolution of that phenomenon, not an already established fact.

Period	Anomaly vs pre-industrial
September 2026	+1.63°C (global)
September 2026	+2.51°C (western Europe)
September 2023	higher (hottest month on record)

The sequence of August and September 2026 above 1.5°C remains, for now, the most concrete element noted by the bulletin: two consecutive months above that threshold had not been recorded since November of last year.