September 2025 was the third hottest September on record globally and the fifth hottest in Europe, according to the European climate monitoring agency Copernicus.
The global average temperature for September 2025 was 16.11°C, 0.66°C higher than the September average for the 1991-2020 period and 1.47°C above the pre-industrial average (1850-1900).
Only September 2024, with an average of 16.18°C, and September 2023, with an average of 16.38°C, were warmer, Copernicus reported.
Samantha Burgess, a climate scientist at Copernicus, noted that global temperature patterns remain unchanged from a year ago, with both land and sea surface temperatures remaining high. She attributed this to the continued accumulation of greenhouse gases in the atmosphere.
The Paris Climate Agreement aims to limit global warming to well below 2°C, preferably to 1.5°C. Temporary temperature increases over several months do not necessarily mean the more ambitious goal is out of reach.
In Europe, last month’s average temperature was measured at 15.95°C, which is 1.23°C above the 1991-2020 average for September.
The global average sea surface temperature in September 2025 was 20.72°C, making it the third highest ever recorded for a September. The highest was in September 2023, at 20.92°C.
