The global daily average sea surface temperature outside the polar regions reached 21.1°C on August 22, 2026, setting a new all-time record, according to data collected from buoys, ships, and satellites and analyzed by the Copernicus Climate Change Service using ERA5 reanalysis datasets [1, 2, 3]. This surpasses the previous record of 21.09°C, which was recorded on three separate days in March 2024 [1, 3].
It is unusual for the ocean temperature to peak in August, as the highest temperatures typically occur in March or April each year [1, 2, 3]. The current record precedes the expected peak of the developing El Niño phenomenon, forecast to occur between November 2026 and January 2027 [1, 2, 3]. El Niño events bring warm waters to the tropical Pacific, further raising global ocean temperatures already elevated by decades of human-driven warming.
Dr. Samantha Burgess, ECMWF's strategic lead for climate, said, "This record is another clear signal of an ocean under growing stress. El Niño is adding heat to the system, but it is doing so on top of decades of human-driven warming. As ocean temperatures continue to rise, the risks to marine ecosystems and coastal communities also increase." [1, 3]
Warmer oceans cause higher sea levels due to thermal expansion, harm marine life, increase marine heat waves, and potentially lead to stronger storms and heavier rainfall [1, 3]. Dr. Jeremy Grist added, "The fact that we are already breaking records is an early indicator of how strong the El Niño is becoming. All things being equal, we might expect the ocean temperature record to be broken again in March [or] April 2027." [1]
The previous highest August temperature was 20.98°C [3]. The current data reflects continuing ocean warming trends and the influence of this year's emerging El Niño event.
The Copernicus Climate Change Service will continue monitoring sea surface temperatures closely through the expected El Niño peak from November 2026 to January 2027 to track further changes and potential impacts [1, 2].
