The Copernicus Climate Change Service (C3S), the European Union’s satellite-based climate monitoring programme, has published global surface and sea temperature data for September.

According to the data, September 2025 recorded an average global surface temperature of 16.11°C, making it the third warmest September on record. This temperature was 0.66 degrees above the 1991–2020 average.

The monthly average was 1.47 degrees warmer than the pre-industrial baseline (1850–1900). Furthermore, the 12-month period from October 2024 to September 2025 saw the global average temperature rise 1.51 degrees above pre-industrial levels.

In Europe, September 2025 was the fifth warmest September on record, with an average temperature of 15.95 degrees, which is 1.23 degrees above the 1991–2020 average.

Globally, sea surface temperatures also marked their third warmest September on record, averaging 20.72 degrees.

Commenting on the findings, Copernicus Climate Change Service (C3S) Deputy Director Samantha Burgess noted that global temperatures in September remained close to those of September 2024: “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,” she said.