World's oceans record hottest June ever as new El Nino takes hold

Global average sea surface temperatures reached 20.98C in June, breaking the previous records set in 2023 and 2024, the European Union's Copernicus Marine Service said.

The first six months of 2026 averaged 20.04C, just below the record set during the same period in 2024.

Scientists said the developing weather pattern could add more heat to both the oceans and the atmosphere through the rest of 2026 and into next year.

Uncharted territory

"Current conditions could indicate the beginning of a new phase, leading, once more, to uncharted territory," Carlo Buontempo, director of the Copernicus Climate Change Service, the EU's climate monitor, said in a statement.

"With ocean temperatures at these levels and El Nino on the horizon, we are likely to see more temperature records fall in the coming months."

El Nino is marked by unusually warm waters in parts of the Pacific Ocean that release more heat into the atmosphere and change weather patterns around the world.

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It can increase the risk of floods in Peru, droughts in parts of Africa and wildfires in Australia, while also temporarily lifting global temperatures.

"With the arrival and the onset of an El Nino year... we can expect that 2026 will be amongst the warmest (ever) recorded," said Simon Van Gennip, lead oceanographer for the Copernicus Marine Service, in a news briefing.

"This is due to El Nino ... but also from the warming due to the greenhouse gas emissions we continue to provide for the atmosphere."

Deepening crisis

The finding follows a warning issued last month in a major United Nations scientific assessment, which said the world's oceans are in a "deepening crisis" as seas warm and rise faster.

Oceans absorb around 90 percent of the excess heat trapped by greenhouse gases.

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Warmer seas add moisture to the atmosphere, helping fuel tropical cyclones and heavy rainfall. They also contribute to sea level rise as water expands when it warms, while prolonged marine heatwaves can bleach corals and kill marine wildlife.

Marine heatwaves affected around 82 percent of the world's oceans during the first half of 2026, the second-largest extent after 2024, the Copernicus Marine Service said.

Regional extremes

The Mediterranean recorded its hottest June at 24.3C, surpassing the previous highs set in 2023 and 2025. Marine heatwaves affected 98 percent of the basin during the first six months of the year.

The tropical Pacific also experienced its hottest June, reaching 27.26C. The region matched its 2016 record for the January-to-June period, with the strongest and most persistent warming in the western equatorial Pacific and off the coasts of Peru and California.

(with newswires)