The world’s oceans have reached their hottest temperature on record, according to European climate monitors, marking a troubling new climate milestone. The Copernicus Climate Change Service reported that global sea surface temperature hit 21.1 degrees Celsius (70.0°F) on August 22, breaking the previous record of 21.09 degrees (69.96°F) set in March 2024.
The Copernicus Climate Change Service, known as C3S, relies on data from the ERA5 dataset, which tracks ocean temperatures back to 1979. Scientists say a single daily record should be viewed carefully within the bigger picture of climate trends.
Still, they note this latest figure fits a pattern of long-term warming across the planet’s oceans, made worse by a strong El Niño event forming in the tropical Pacific.
World’s oceans hit their hottest temperature in August
What makes this record especially unusual is its timing. Ocean temperatures usually peak in March and April, right after summer ends in the Southern Hemisphere. This year’s record came in August instead.
It also surpassed the previous high for the month of August, which was 20.98 degrees Celsius (69.76°F), set in 2023. The new reading follows months of near-record and record-breaking figures throughout 2026, confirming that the world’s oceans are now sitting at their hottest average temperature since detailed tracking began in 1979.
Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts, said the record shows the ocean is under growing pressure. She explained that El Niño is adding extra heat to waters already warmed over decades by human-driven climate change.
Burgess added that as ocean temperatures keep climbing, so do the dangers facing marine life and coastal communities. She pointed out that the number of days with marine heatwaves around the world has more than tripled since the early 1990s, putting growing strain on ocean ecosystems and the people who depend on them.
El Niño set to intensify as ocean impacts mount
Weather officials expect the current El Niño to grow stronger in the coming months, with C3S forecasters saying it could reach a strength not seen in several decades.
Rising ocean temperatures carry wide consequences. Warmer water expands, which adds to sea level rise and raises risks for coastal towns and small island nations. Heat also fuels marine heatwaves that damage coral reefs and seagrass beds, disrupting food chains and industries such as fishing.
A hotter ocean can also add more moisture to the atmosphere, which may strengthen rainfall and storms. It becomes less able to absorb carbon dioxide too, weakening one of the planet’s key defenses against climate change.
Scientists at ECMWF said they will keep watching the data closely to see whether this heat spike fades or continues.
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