Last month was the hottest September on record around the world, scientists said.
Surface air temperatures globally were 0.05C (0.09F) warmer on average than in September 2019.
The difference was even more marked in Europe, with the previous September record for the continent in 2018 beaten by 0.2C (0.36F).
Temperatures were also well above average in other parts of the world including the Middle East, parts of South America and Australia, said the EU's Copernicus Climate Change Service.
Meanwhile, the Siberian Arctic was also warmer than average in a hot spell that has affected parts of the region since early spring.