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August was the hottest month ever recorded globally, with ocean temperatures also reaching unprecedented highs as western Europe capped its warmest summer on record, the EU's Copernicus Climate Change Service said Thursday.
Global average air temperatures in August reached 16.96 degrees Celsius (62.53 degrees Fahrenheit), Copernicus said, surpassing by 0.01°C the previous all-time monthly record set in July 2023. Copernicus said the narrow margin meant the two months were considered joint-highest.
Copernicus observations go back to 1940, but other evidence, including ice cores, tree rings and coral skeletons, allows scientists to place current conditions against a longer historical record.
"Humans haven't seen temperatures as hot as today for, arguably, at least the last 100,000 years," Samantha Burgess of the European Centre for Medium-Range Weather Forecasts, which oversees Copernicus, said.
Scientists say human activity, primarily the burning of coal, oil and gas, has warmed the planet by roughly 1.4°C since pre-industrial times and increased the severity and likelihood of extreme weather. Heat-trapping greenhouse gas emissions rose to new highs in 2025.
Responding to the Copernicus assessment, United Nations climate chief Simon Stiell said the data reflected the continued reliance on fossil fuels and the climate impacts linked to it.
Global sea surface temperatures also set a new daily high and tied for equal-hottest in August, extending a three-month streak of record warmth across the world's oceans.
More than 90% of excess heat trapped by greenhouse gas emissions has been absorbed by the oceans, a process that has spared land from additional warming but placed severe strain on marine life, reefs and coastal communities.
Records were broken in the Atlantic, the Mediterranean and the tropical Pacific, where the strongest El Nino pattern of the modern era is gaining strength.
El Nino episodes, a natural warming phase in the Pacific, typically bring a temporary rise in global temperatures already elevated by long-term warming, and are associated with shifts in weather patterns worldwide, including floods, droughts and wildfires in different regions.
Scientists expect the current El Nino to peak in intensity around December, with 2027, and potentially 2026, projected to become the hottest years on record.
"Climate change makes every El Nino hotter, and until we stop burning coal, oil and gas these record-shattering months will simply keep on coming," Friederike Otto, a climate scientist at Imperial College London, said.
Copernicus said August marked the end of western Europe's warmest summer on record, surpassing the previous record set in 2003.
The June to August period included consecutive heatwaves that closed schools, reduced river levels and contributed to conditions favorable for wildfires.
Between mid-July and mid-August, the EuroMomo monitoring platform estimated more than 32,000 excess deaths across Europe.
Researchers from the World Weather Attribution network found that a heat wave in June would have been "virtually impossible" without the influence of climate change.
Elevated temperatures were also recorded outside Europe. On Sept. 9, the National Oceanic and Atmospheric Administration reported that the contiguous United States had its hottest summer on record.
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