According to the latest Climate Bulletin of the Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF) under the Copernicus programme, May 2025 the second warmest May in the history of measurements worldwideThe temperature was only 0.12°C colder than the record-breaking May 2024. This bulletin provides a comprehensive overview of global temperatures, sea surface temperatures, hydrological conditions, and sea ice extent.

Global temperatures and an important threshold

The average global air temperature at the Earth's surface in May 2025 reached 15.79 °CThis is 0.53°C above the average for the reference period 1991-2020. Even more remarkable is that May was 1.40°C above the estimated pre-industrial average from 1850–1900May 2025 was only the second month in the last 23 months in which the average global temperature did not exceed the 1.5°C threshold set by the Paris Agreement. C3S Director Carlo Buontempo noted that while this may “offer a short respite” for the planet, the 1.5°C threshold is expected to be exceeded again in the near future due to continued warming of the climate system.

The boreal spring season (March to May) was also globally the second warmest in the history of measurements, with an average air temperature at the Earth's surface 0.59 °C above the 1991–2020 average, surpassed only by the spring of 2024.

Sea surface temperatures (SST)

The average sea surface temperature in May (between 60°S and 60°N) reached 20.79 °C, the second highest value for the month and only 0.14°C below the record set in May 2024. Sea surface temperatures remained unusually high in many ocean basins and seas. Large areas in the northeastern North Atlantic experienced a marine heatwave and record high sea surface temperatures for a given month.

Hydrological contrasts in Europe and the world

May 2025 brought marked contrasts in precipitation and soil moisture. In Europe, northern and central parts, including parts of Russia, Ukraine and Turkey, faced significantly drier than average conditions. Conversely, southern Europe, the regions of Fennoscandia, and parts of western Russia were much wetter than averageOverall, there were marked contrasts between wet and dry conditions during the European spring, with drier conditions in the north and west contributing to the lowest spring river flow in all of Europe since measurements began in 1992.

Outside Europe, drier than average conditions were recorded in the Horn of Africa, Central Asia, southern Africa, Australia and South and North America, where these conditions contributed to the spread of large-scale wildfires in Canada. Wetter than average conditions were reported in Alaska, eastern North America, Russia, southern South America and northern Australia, with flooding has been reported in New South Wales, Australia, northeast India, and the Mid-Atlantic region of the USA.

Sea ice extent

Arctic sea ice extent in May was only 2 % below the 1991–2020 average, representing 9th lowest value in a month in the 47-year satellite record. In Antarctica, sea ice extent was 9 % below average, with a mixed pattern of areas of above- and below-average concentration, related to the location of high and low pressure systems around the continent.

The Copernicus Climate Change Service provides these monthly updates on key climate indicators, which are based primarily on the ERA5 reanalysis dataset. Spring