Ocean temperatures last month were hotter than any other July on record fuelled by severe heatwaves across Western Europe and developing El Niño conditions in the equatorial Pacific, according to Copernicus Climate Change Service.

The average sea surface temperatures for the non-polar regions of the ocean were the highest on record for the month, at 20.96°C, surpassing the previous July record of 20.89°C, which was set in 2023. 

Europe suffered widespread strong or severe marine heatwave conditions, particularly along the Atlantic coast and western Mediterranean. Sea surface temperatures will remain at exceptionally high levels across the tropical Pacific, where current El Niño conditions are forecast to further strengthen in the coming months.

June-July also saw an intense heatwave in western Europe, with air temperatures sitting 2.79°C above average. A lack of rainfall has caused severe drought, with moisture levels being significantly lower than those in July 2022 – the last summer in which Europe suffered a severe drought. As a result, river levels have fallen sharply, with the Seine, Rhine, and Danube among those affected, adding pressure to water supplies, agriculture and energy production.

Climate-change induced marine heatwaves and drought are anticipated to affect fishers and farmers. 

Heightened water temperatures cause mass die-offs in critical nursery ecosystems like kelp forests, causing future fish populations to collapse. Lobsters, crabs, scallops, clams, and oysters also suffer devastating die-offs, unable to escape “seafloor heatwaves”, and farmed salmon, mussels, and oysters – kept in coastal pens or on ropes – cannot escape the warming waters and frequently suffocate due to sudden drops in oxygen levels.

Drought conditions and wildfires are also leading to crop failure across Europe. In 2026, 500 852 hectares of land had been burnt since the start of the year, that’s roughly the size of the country of Trinidad and Tobago. 

Samantha Burgess, Strategic Lead for Climate at ECMWF said: “As soils dry out, they lose their ability to provide natural cooling, allowing heat to build more readily. This is a clear example of how climate change is intensifying heat extremes, with heat and drought increasingly reinforcing one another.”

As man-made climate change increasingly drives temperatures up, the ocean has absorbed an increasing amount of heat energy. In 2025, the heat added was the equivalent of about 12 Hiroshima-scale nuclear bombs exploding every second of every day.

When ocean temperatures rise, they lose their ability to cool off nearby land during summer. They also evaporate faster, making the air more humid and driving heavier, more sudden rainstorms and floods.

Director of Campaign for Nature, Brian O’Donnell said: “Governments have become very good at documenting these records. Now they need to become much better at safeguarding the forests, wetlands and oceans that help regulate the climate and protect communities from the impacts of a warming world.”

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