The world’s seas were hotter last month than in any July on record, scientists have said, as devastating heat struck western Europe.

Sea surface temperatures hit record highs for July on the Atlantic coast and western Mediterranean, the EU’s Copernicus climate change service found, with severe marine heatwaves roiling Europe’s seas. Globally, the average sea surface temperature outside the cold polar regions was the highest on record for the month, beating the previous July record set in 2023.

Surface air temperatures around the world in July 2026 were marginally cooler than July 2024 – by just 0.01C – leading scientists to consider the two months as the joint-second warmest Julys on record.

Western Europe has experienced its hottest June-July period on record, data shows, with “exceptional” heat driving wildfires that devastated swathes of the Mediterranean.

The first two summer months of 2026 were 2.79C hotter than usual, the Copernicus said on Monday, beating the previous record set four years ago and reflecting the “exceptional persistence of heat” since the season began.

Central Europe is reeling from a heatwave in which national temperature records fell in a handful of countries including Austria and Slovakia. It is the latest in a scorching summer that has dried out vegetation and primed the continent to burn.

Samantha Burgess, a climate scientist at the European Centre for Medium-Range Weather Forecasts, said this summer had been “a clear example” of climate breakdown intensifying extremes that reinforce each other.

“[As] persistent high-pressure systems trapped heat over western Europe, the extreme temperatures also amplified widespread drought,” she said. “As soils dry out, they lose their ability to provide natural cooling, allowing heat to build more readily.”

Supercharged by fossil fuel pollution, a string of heatwaves have hit Europe since the end of spring, with particularly brutal heat at the end of June expected to have resulted in more than 10,000 deaths.

Copernicus said widespread dryness observed in May and June intensified last month, with exceptionally low rainfall and soil moisture in much of western Europe. Across the dry regions, which include France, Spain, and parts of Germany and the UK, low river flows hit water supply, irrigation and power plants, including in countries downstream. Short of cooling water, two coal-fired power plants were forced to shut in Poland last week, as well as Hungary’s sole nuclear power plant, for the first time in its 44-year history.

Heat and drought are among the biggest environmental threats to Europe’s economy. Early estimates for this summer suggest the June heat cost grain farmers €2bn in lost crops.

The longer-term damage can eclipse short-term losses, economists warn, particularly if droughts persist over many years. The mega-drought of 2015-18 cost Europe €439bn, a new working paper led by the CMCC European Institute on Economics found, with high but short-lived hits to agriculture and low but persistent impacts on manufacturing and construction. The researchers argue that conventional methods substantially underestimate drought-related economic losses as they fail to capture the years after.

Marta Mastropietro, a researcher at CMCC and the Polytechnic University of Milan, and lead author of the study, said: “Even a single dry year causes real economic damage, but a persistent drought is different: its effects can compound across sectors and keep accumulating for years afterward.

“That intersection between compounding and long-lasting impacts is what conventional impact estimates tend to miss.”

About half a million hectares have burned across the EU since the start of the year, data published by the European Forest Fire Information System shows, accompanied by above-average pollution as burning vegetation spews thick smoke. The hot, dry and windy conditions that make it harder to battle blazes has set new records for severity for this time of year.

Víctor Resco de Dios, a professor of forestry engineering at the University of Lleida, said: “Climate change is creating increasingly favourable conditions for the development of mega-wildfires.

“The good news is that through vegetation management and urban planning we can largely mitigate the problem,” he said. “However, we must be clear about one thing: what seems extreme to us today will be remarkably benign in a few decades if we continue to fail to take the necessary adaptive measures.”