The latest Climate Bulletin, published by the Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Commission, brings alarming data for August 2025. This month was Globally, the third warmest August on record, with southwestern Europe experiencing its third significant heatwave this summer, contributing to widespread forest fires and heat stress. This publication also celebrates the tenth anniversary of the monthly Climate Bulletins.

Global temperatures continue to rise

August 2025 was only 0.22°C cooler than the two warmest Augusts recorded, in 2023 and 2024. Globally, the average surface air temperature in August was 16.60°C, which is 1.29°C above the estimated pre-industrial level (1850–1900) and 0.49°C above the average for this month from 1991–2020. However, August 2025 was only the fifth month in the past 26 months in which the global average surface air temperature did not exceed 1.5°C above the pre-industrial level. However, the global average temperature over the past 12 months (September 2024–August 2025) still remained above this level, at 1.52°C. Samantha Burgess, Strategic Climate Lead at ECMWF, stressed that these events, including unusually warm global oceans, underscore not only the urgency of reducing emissions, but also the critical need to adapt to more frequent and intense climate extremes.

Third summer heatwave in southwestern Europe

In Europe, the average land temperature in August was 19.46°C, 0.30°C above the 1991–2020 average. This value placed it outside the top ten warmest Augusts on record. However, south-western Europe experienced its third major heatwave this summer, starting in Portugal in late July and spreading to Spain and southern France in early August. The heatwave lasted until 18 August, with daily maximum temperatures reaching 40°C in most of the region, peaking at 45°C in Portugal and southern Spain. Based on data from the C3S Thermal Trace app, most of the affected regions experienced “very severe heat stress”, corresponding to a “felt temperature” of between 38°C and 46°C. Parts of northeastern and southern Spain and southern Portugal even experienced “extreme heat stress” (feels like 46°C or higher). Conversely, most of northern Europe, including Fennoscandia, the Baltic states, Belarus and Poland, experienced below-average temperatures in August.

Dry conditions and widespread forest fires

August 2025 brought mostly drier-than-average conditions to most of western, central and southern Europe, as well as southernmost Sweden, northwestern Russia and parts of Finland. In southwestern Europe, these dry conditions, exacerbated by heat waves, contributed to significant forest fires, particularly in the Iberian Peninsula and Greece. By the third week of August, carbon emissions from forest fires in Spain, as monitored by the Copernicus Atmosphere Monitoring Service, had increased dramatically, reaching their highest annual total since records began in 2003. Outside Europe, drier-than-average conditions were also recorded in the western, central and eastern US and much of Canada in August, contributing to ongoing forest fires. Conversely, wetter than average conditions affected northeastern Spain, southern France and Germany, Switzerland, most of Italy and other areas, where strong storms caused flooding and landslides with reported damage and casualties.

Sea ice status

In the Arctic, sea ice extent in August 2025 was close to the annual minimum expected in September. The average sea ice extent was 5.9 million km², 12 % below the 1991–2020 average and the eighth lowest August on record. The most significant negative anomalies were recorded in the European Arctic sector, north of Svalbard, Franz Josef Land and Nordland. Around Antarctica, sea ice concentrations continued to show contrasting areas of above- and below-average values in August, influenced by shifting pressure systems. Antarctic sea ice extent was 7 % below average, or 16.9 million km² – the third lowest August on record.

The information from the monthly C3S bulletins, which cover surface air temperatures, hydrological variables and sea ice, is based on data from the ERA5 reanalysis and provides key insights into the current state of the climate. These findings reiterate the the urgent need for global action in the fight against climate change and adaptation to its ongoing consequences. JRi

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