World’s seas hit hottest July temperature on record, scientists say

Last month saw the highest average sea surface temperature ever recorded for July across the extra-polar oceans, or the oceans free of seasonal sea ice, according to the European climate agency Copernicus.

Heatwaves sweeping Europe this summer also toppled the average temperature record for the June-July period set in 2022, the agency said.

The extreme heat began in May and has contributed to major wildfires, prolonged drought and new national temperature records across Europe, as well as thousands of projected heat-related deaths.

Globally, so far this is the third-hottest year, behind 2024 and 2025, climate statistics show. But 2026 still has time to catch up.

Devastating wildfires have swept across Europe this summer. / Credit: AP

Thanks to the combination of accelerated human-caused global warming and a supersized El Niño, a periodic warming of parts of the Pacific that leads to temperature variations around the globe, there’s an increasing chance that by the end of the year, 2026 could become the hottest year on record, beating out 2024 — or at least come close, scientists said.

The record-breaking rise in average sea surface temperature was partially fueled by developing El Niño conditions in the equatorial Pacific, the service said.

The new average record for July is 20.96 degrees Celsius (69.73 degrees Fahrenheit), which beat the 2023 record of 20.89 C (69.60 F).

However, last month’s average surface air temperature globally was 16.90°C (62.42 F), making it only the joint second warmest July on record and tied with July 2024, Copernicus reported.

In Western Europe, meanwhile, the average temperature record for the June-July period hit 21.62°C (70.92 F), Copernicus said.

“Persistent high-pressure systems trapped heat over western Europe, the extreme temperatures also amplified widespread drought,” said Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts.

“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.”

Recent years have seen an increasing number of marine heatwave events around the UK, according to the Met Office.

Scientists say 2025 was particularly exceptional, with marine heatwave conditions persisting for more than three-quarters of the year. Similar events were also recorded in 2022 and 2023, while 2026 has once again seen sea temperatures significantly above average.

At the same time, cold marine conditions have become increasingly rare. The last widespread cold spell affecting UK waters occurred during the Beast from the East in 2018. Since then, winters have tended to feature above-average sea temperatures.

Warmer seas can have important consequences for marine life and ecosystems. Species that are typically found further south can expand their range northwards when waters remain unusually warm for prolonged periods.