Extreme weather and climate-related disasters raged around the world last month.
Scientists have said climate change likely played a role in the landslides and flash floods that killed hundreds in Nepal and China's Tibet, although the specifics are still being studied. Wildfires surged from Indonesia to Greece and Belgium, while severe drought struck Hungary and Romania.
Temperatures of more than 1.5C above pre-industrial times are significant because that temperature, when measured as a decades-long average, is the level of warming 193 countries and the European Union vowed to try to prevent under the 2015 Paris climate agreement, in order to avoid the worst consequences of climate change.
August was the first month since November 2025 in which the world's average temperature exceeded 1.5C above pre-industrial levels.
With an average global surface air temperature of 16.96C, August tied with July 2023 as the world's warmest month on record. This was 1.65C hotter than the planet's average temperature in the 19th century, before humans started burning oil, coal and gas on an industrial scale, C3S said on Thursday.
Emissions from burning these fossil fuels are the main cause of climate change.
"We've really seen the impact across Europe of how maladapted we are, with roads melting, train lines buckling, schools closing, hospitals completely overwhelmed, and record wildfires for the time of year," said Samantha Burgess, strategic lead at the European Centre for Medium-Range Weather Forecasts.
"The narrative around climate change has really transitioned from being quite an abstract concept that happens in a faraway place, to disrupting our daily lives," she said.
The data confirmed western Europe is emerging from its hottest summer ever recorded, with many regions suffering unusually low river flows and soil moisture — adding to farmers' woes, after a succession of extreme heatwaves since May ravaged crops.
The world has not yet technically breached the Paris Agreement's 1.5C target — which refers to an average temperature over decades, rather than a temporary peak. Currently, the world's long-term warming level is about 1.4C above pre-industrial levels.
The United Nations last week said sticking to the long-term 1.5 C goal is no longer possible. It urged governments to cut CO2 emissions faster, to limit overshooting the target.
C3S's records go back to 1940, and are cross-checked with global temperature records going back to 1850.
August's extreme heat was not limited to land. The world's oceans outside of the polar regions also recorded their joint-highest sea surface temperature for any month on record, C3S said.
In the tropical Pacific, record-high temperatures were fuelled by the formation of the El Nino weather pattern, which is forecast to strengthen in the coming months — potentially pushing up global temperatures further.
