Scientists have confirmed the record for the hottest sea surface temperatures was broken last week.
The new high of 21.1°C beats the previous record set in 2024, during the last major El Niño.
In Australia, El Niño conditions mean weather will normally be hotter and drier than usual, starting from late winter.
The new record was set months after ocean temps are usually at their peak.
Let's unpack.
Glossary
Here's what you need to know to understand this story.
Sea surface temperature: The temperature of the top level of the ocean, which tells scientists about climate change and marine animals' health.
Copernicus Climate Change Service (C3S): The European Union's climate monitoring service.
It has tracked the average global sea surface temperature every day since 1979.
El Niño: A recurring weather pattern alternating with La Niña.
In Australia, it causes higher temperatures and can lead to droughts.
Record
In a press release on Monday, C3S said 22 August saw the hottest sea surface temperatures on record, at 21.1°C.
The previous record, 21.09°C, was set in March 2024, during a strong El Niño.
The weather pattern temporarily pushes global temperatures higher, on top of long-term warming from climate change.
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Here are the average daily sea surface temperatures for 2026, compared to the average daily temperatures recorded between 1991 and 2020.
Global ocean temperatures usually peak in March and April, so a record in August is unusual.
Explanation
Scientists say two factors are stacking on top of each other.
Decades of human-driven climate change have already warmed the oceans.
At the same time, a powerful El Niño is developing in the Pacific, and forecasters expect it to keep strengthening over coming months.
C3S said this El Niño could be the strongest in decades.
Impact
A warmer ocean makes sea levels rise faster, because water physically takes up more space as it warms up.
It also fuels more intense marine heatwaves, which damage coral reefs and cause more frequent and more damaging algal blooms.
Warmer oceans can supercharge extreme weather, since warmer water pumps more heat and moisture into the atmosphere.
What's next?
The latest data from the Bureau of Meteorology shows a strong El Niño is already locked in, and it's expected to keep intensifying through spring.
Some international forecasters have flagged the possibility of a "super" event this year, though a stronger El Niño doesn't always mean worse impacts here.
In Australia, El Niño years tend to bring warmer temperatures and drier conditions across central and eastern parts of the country, especially in winter and spring.
