The world’s daily average sea surface temperature has climbed to its highest level on record, according to the European Union’s Copernicus Climate Change Service, raising fresh concerns over mounting pressure on the world’s oceans.
The average temperature across the extra-polar global ocean — between 60 degrees south and 60 degrees north — reached 21.1°C (69.98°F) on August 22, narrowly surpassing the previous record of 21.09°C set in March 2024.
The figures are based on the ERA5 dataset produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), with reliable records extending back to 1979.
Copernicus said the timing of the new record was particularly significant because global sea temperatures normally reach their annual peak in March or April, following the Southern Hemisphere summer.
The latest reading also surpassed the previous August record of 20.98°C, set in 2023, and follows a series of record or near-record ocean temperatures during 2026.
Scientists are also monitoring the development of El Niño, which the World Meteorological Organization expects to strengthen in the coming months. Copernicus forecasts suggest the phenomenon could reach an intensity not seen for several decades.
“This record is another clear signal of an ocean under growing stress,” said Samantha Burgess, ECMWF’s strategic lead for climate.
“El Niño is adding heat to the system, but it is doing so on top of decades of human-driven warming,” she added.