The World’s Oceans Are The Hottest On Record For June 2026

Sydney : The world’s oceans are the warmest on record for June, surpassing records set during the 2023-24 El Nino years.

Currently, the average sea surface temperature in the world’s tropical and temperate oceans is just under 21°C. Before widespread industrialization in 1870, the temperature was approximately 19.6°C.

This may not seem like a big difference. But heating the world’s oceans this much requires a truly enormous amount of energy. More than 90% of the extra heat trapped by greenhouse gases from burning coal, gas and oil went into the world’s oceans.

As a result, the oceans are warming rapidly. The added heat in 2025 was equivalent to approximately 12 Hiroshima-scale nuclear bombs exploding every second of every day.

To find a climate analogue comparable to what is happening in the oceans now, we would have to go back about 120,000 years, before the last ice age. At that time, slow shifts in the Earth’s orbit caused it to gradually warm over thousands of years. Humans reached a similar conclusion in just over a century.

But the temperature in the ocean doesn’t just stay there. Warmer oceans foster stronger hurricanes, a wetter atmosphere, heavier precipitation, and more heat in marine air masses; This could make heatwaves over land more likely and more intense.

The El Niño currently occurring in the tropical Pacific is likely to be large. As it continues to develop, we can expect to see higher temperatures and extreme events such as marine heat waves in the western Indian, tropical Atlantic and eastern Pacific Oceans.

Where are the hotspots on land and in the ocean?

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Europe is being overwhelmed by a record-breaking heat wave. The oceans and enclosed seas surrounding the region are also extremely warm.

Parts of the Mediterranean are up to 6°C warmer than the long-term average.

Some parts of the North Sea are up to 3°C warmer than average.

The resulting El Niño caused sea surface temperatures to be approximately 1.24°C warmer than average across a wide region of the central-eastern Pacific.

There is also much more heat below the surface. Subsurface conditions in the Eastern Pacific are 6°C above average.

A typical El Nino lasts about a year. The full effect on atmospheric temperature becomes most pronounced towards the end of the cycle. This means we can expect 2026 to be very hot (perhaps a new record), while next year could be even warmer as ocean heat is transported back to the surface. We saw this during the El Niño events of 2023-24 and 2015-16.

Longer-lasting and more intense marine heat waves combined with steady ocean warming pose major threats to marine ecosystems such as coral reefs, seagrass meadows, and coastal reefs. Studies on the 2023-24 El Niño and the warm year 2024 showed widespread effects.

From oceans to land

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What happens in the oceans does not stay there.

A record-breaking marine heatwave in June 2023 broke previous temperature records in the North Atlantic Ocean. Soon large areas of Europe were affected by intense heat waves, while heavy rainfall caused deadly floods in Spain and raging forest fires broke out around the Mediterranean.

Rising ocean temperatures have many consequences.

A warmer ocean may be less able to cool the land during the summer. Warmer oceans also lead to more evaporation, increasing humidity and causing more intense and sudden extreme rainfall and flooding. These can have devastating consequences.

There is a clear geographical pattern during El Niño events. The regions we expect to be warmer or colder during El Niño roughly reflect where we are more or less likely to experience marine heat waves and more intense tropical cyclones.

Typical hurricane regions, such as the western Indian Ocean, may see stronger hurricanes that drop more precipitation when they hit land. El Niño tends to cause extreme rain and floods in western South America and dry conditions in Australia and parts of Southeast Asia.

Can we prepare?

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We’re better understanding how major climate factors like El Niño shape weather and how to use ocean data from around the world to develop better seasonal forecasts that authorities can use to prepare.

Over the past two years, we have improved our ability to predict marine heatwaves three to four months in advance in Australia, the United States and other regions. The forecasts give marine authorities a chance to take early action by reducing the amount of allowable catches and starting conservation efforts for sensitive species.

This early success in ocean forecasting may be short-lived. The current US administration last year cut funding for climate data collection networks and worked to disband the National Center for Atmospheric Research.

This year, the administration announced it would end funding for a key ocean monitoring network before backing off.

Continuous collection of ocean data is crucial for ocean and land forecasts. If these are weakened or halted, we may face the challenge of blindly coping with worsening climate impacts.

Ending climate change measurements will not stop this from happening. The only way to prevent climate change from getting worse is to reach net zero as quickly as humanly possible. We must use forecasts to prepare for things we cannot prevent until then. (Chat)