According to the European Union’s Copernicus Marine Service, the global average sea surface temperature reached around 21.0 degrees Celsius in June, surpassing the previous records set in 2023 and 2024.
The world’s oceans just experienced their hottest June on record and could set fresh highs in the months ahead as El Nino and climate change drive temperatures even higher.
Global average sea surface temperatures in June were 20.98C, beating the previous records of 2023 and 2024 pic.twitter.com/dSfGdjHxPf
— AFP News Agency (@AFP) July 1, 2026
Marine heatwaves spread across the globe
According to the EU’s marine environment monitor, the first half of 2026 was marked by unusually warm ocean temperatures and widespread marine heatwaves. By the end of June, around 82% of the world’s oceans had been affected by marine heatwaves.
“Marine heatwaves expanded steadily throughout the period, ultimately affecting around 82 percent of the global ocean,” Simon van Gennip, lead oceanographer for the Copernicus Marine Service, was quoted as saying by Al Jazeera.
The Mediterranean Sea, the central North Atlantic and the equatorial Pacific were among the regions that recorded particularly high temperatures, indicating that oceans are under sustained heat stress.
El Niño could push temperatures higher
Scientists said the possible return of El Niño later this year could further increase temperatures in both the oceans and the atmosphere. Carlo Buontempo, Director of the Copernicus Climate Change Service, said current conditions could signal the beginning of “new phase, leading, once more, to uncharted territory.”
“With ocean temperatures at these levels and El Niño on the horizon, we are likely to see more temperature records fall in the coming months. That Copernicus Marine data reaches the same conclusion through independent methods speaks to the strength of European science — and to why open, robust data matters now more than ever,” Buontempo added.
Why warmer oceans matter
The report comes weeks after a major UN scientific assessment warned that the world’s oceans are facing a ‘deepening crisis’ as they continue to warm and sea levels rise. Oceans absorb around 90% of the excess heat generated by greenhouse gas emissions, helping regulate the Earth’s climate. However, rising ocean temperatures also increase moisture in the atmosphere, making heavy rainfall and tropical cyclones more intense.
Warmer seas also contribute to rising sea levels and place additional stress on marine ecosystems, including coral reefs, which can bleach and die during prolonged marine heatwaves.
What is El Niño?
El Niño is a climate pattern caused by unusually warm waters in the tropical Pacific. According to the World Meteorological Organization (WMO), the conditions are developing and is expected to influence global temperatures and rainfall, raising the likelihood of extreme weather in the months ahead.
