Global oceans hit hottest June on record, scientists warn of more heat ahead

The world's oceans recorded their hottest June in history, with global average sea surface temperatures reaching 20.98°C and surpassing previous records set in 2023 and 2024, according to data released Wednesday by the European Union's Copernicus Marine Service and the Copernicus Climate Change Service.aljazeera+1

On June 21, the daily global average hit 21.0°C — exceeding the 2023 record of 20.83°C and the 2024 record of 20.86°C by roughly 0.1°C, the services confirmed. The tropical Pacific also registered its hottest June ever at 27.26°C.france24+1

Six Months of Unprecedented Ocean Warmth

The June record capped what the Copernicus Marine Service described as six months of "persistently elevated sea-surface temperatures and widespread marine heatwaves across much of the global ocean". Ocean temperatures in 2026 have reached levels "not previously observed in the satellite record," the service said.x+1

Scientists say the record warmth is being driven by the convergence of long-term human-caused climate change and the onset of El Niño, a periodic warming of the tropical Pacific that reshapes weather patterns globally. The World Meteorological Organization confirmed the onset of El Niño conditions on June 2, warning that the phenomenon would bring above-average temperatures "nearly everywhere" and fuel more extreme weather.news.un+1

Potential for a Historic El Niño

The WMO projected an 80 percent probability of El Niño conditions between June and August 2026, rising to 90 percent through November. Some scientists have raised the possibility that this event could become one of the strongest on record. Paul Roundy, a professor of atmospheric science at the University at Albany, told BBC Science Focus in May that he estimated "roughly a 50 per cent chance of the event becoming the strongest in the historical record".wmo+2

What Comes Next

Scientists warn that the combination of El Niño and background warming could push global temperatures further into what researchers describe as "uncharted territory" in the months ahead. The record ocean heat carries cascading consequences — fueling sea level rise, intensifying extreme weather on land, and threatening marine ecosystems already under stress from prolonged heatwaves. A marine heatwave that began off the U.S. West Coast last summer had already raised coastal water temperatures 3 to 4 degrees Fahrenheit above normal before El Niño's emergence, according to NOAA.euronews+2