World's seas hit record high temperatures in July amid European heatwaves

The world's oceans registered their hottest July on record in 2026, scientists reported, as devastating heatwaves gripped western Europe. Sea surface temperatures hit unprecedented highs for the month along the Atlantic coast and in the western Mediterranean, according to the EU's Copernicus climate change service.

Globally, average sea surface temperatures outside the polar regions were the highest ever recorded for July, breaking the previous record from 2023. While global surface air temperatures in July 2026 were marginally cooler than in July 2024, scientists consider the two months to be the joint second-warmest Julys on record.

Western Europe endured its hottest June-July period, with exceptional heat fueling wildfires across the Mediterranean. The first two summer months were 2.79 degrees Celsius hotter than average, demonstrating a "exceptional persistence of heat" since the season began. Central Europe also faced a heatwave, with national temperature records falling in countries like Austria and Slovakia.

Samantha Burgess, a climate scientist at the European Centre for Medium-Range Weather Forecasts, described the summer as a "clear example" of climate breakdown intensifying interconnected extremes. High-pressure systems trapped heat over western Europe, leading to widespread drought. As soils dry out, their natural cooling capacity diminishes, allowing heat to build more rapidly.

Fossil fuel pollution has supercharged a series of heatwaves hitting Europe since late spring. The intense heat at the end of June is estimated to have caused over 10,000 deaths. Widespread dryness observed in May and June intensified in July, with exceptionally low rainfall and soil moisture in much of western Europe. This has impacted water supply, irrigation, and power plants, forcing some coal-fired power plants and Hungary's sole nuclear power plant to shut down due to a lack of cooling water.

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