At a global level, May 2025 was the second-warmest May since records began, with surface air temperatures averaging 15.79°C, according to the latest data from the Copernicus Climate Change Service (C3S).
This is 0.53°C above the 1991–2020 average. While May 2025 was slightly cooler than the corresponding month a year earlier, it remained 1.40°C above pre-industrial levels.
This interrupted a 21-month streak of periods in which global temperatures exceeded 1.5°C, the data showed.
‘An unprecedentedly long sequence’
“May 2025 breaks an unprecedentedly long sequence of months over 1.5ºC above pre-industrial,” commented Carlo Buontempo, director of C3S at ECMWF.
“Whilst this may offer a brief respite for the planet, we do expect the 1.5ºC threshold to be exceeded again in the near future due to the continued warming of the climate system.”
In Europe, the average land temperature stood at 12.98°C in May, slightly below average, with below-average temperatures recorded in eastern Europe, from eastern Italy and the Balkans to Finland, and above-average temperatures in western Europe.
Outside of Europe, meanwhile, above average temperatures were recorded over western Antarctica, a large area of the Middle East and western Asia, northeastern Russia, and northern Canada. In India, Alaska, southern Africa, and eastern Antarctica, however, temperatures were below average.
Sea surface temperatures
Sea surface temperatures also remained high, with May 2025 seeing the second-highest value on record, of 20.79°C. This was 0.14°C below the May 2024 record.
The northeastern North Atlantic reported a marine heatwave, with record temperatures set in that region, while the Mediterranean remained warmer than average.
Spring 2025 was exceptionally dry in parts of northwestern Europe, with the lowest precipitation recorded since at least 1979 in parts of north-western Europe.
Sea ice levels also continued to decline, with Arctic sea ice extent coming in at 2% below average, marking the ninth-lowest May extent on record. In the Antarctic, sea ice was 9% below average.
‘Antarctic sea ice showed alternating areas of above- and below-average concentrations, shaped by the positioning of high- and low-pressure systems around the continent,’ C3S noted. Read more here.
