Australia's ocean temperatures reached a record high in 2025, according to Weatherzone, due to a number of climate drivers.
The weather service reported the mean annual sea surface temperature in Australia last year was 21.13 degrees, which is 0.93 degrees above the 1961-1990 average.
This was the country's warmest annual anomaly in records dating back to 1900, beating the previous record of +0.90 degrees in 2024.
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"Heat at the surface of the ocean is driven by warmth in the atmosphere and distributed by wind and ocean currents," Weatherzone's Ben Domensino said.
"Unsurprisingly, 2025 was also one of the warmest years on record for air temperatures in Australia and this abnormal atmospheric heat helped to warm the ocean's surface in the Australian region.
"In addition to this near-record atmospheric warmth, abnormally warm water was also pushed towards Australia by La Niña and a negative Indian Ocean Dipole in 2025.
"Both climate drivers enhanced westward and eastward wind patterns respectively, which pushed warm ocean water towards Australia's coasts, causing significant heat build-up to the north-east and north-west of the country."
The increase in ocean heat was particularly noticeable to the east of Australia in the Coral Sea and Tasman Sea with annual sea surface temperatures more than one degree above the long-term averages.
"This was the first time in recorded history that either sea has exceeded the 1961-1990 average by more than one degree," Domensino said.
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