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2025 was Australia's warmest year on record for ocean temperatures

Source Weatherzone Tue 20 Jan 2026

Australia’s ocean temperatures reached a record high in 2025, with sea surface temperatures warming close to 1°C above the long-term average. The mean annual sea surface temperature in the Australian region during 2025 was 21.13°C, which is 0.93°C above the 1961-1990 average. This was Australia’s warmest annual anomaly in records dating back to 1900, beating the previous record of +0.90°C in 2024. Image: Annual sea surface temperature anomaly for the Australian region between 1900 and 2025. Source: Bureau of Meteorology. Climate drivers and atmospheric heat behind record ocean warmth Heat at the surface of the ocean is driven by warmth in the atmosphere and distributed by wind and ocean currents. 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 northeast and northwest of the country. Record warmth in Coral Sea and Tasman Sea The build-up of ocean heat was particularly apparent to the east of Australia, with the Coral Sea and Tasman Sea both registering annual sea surface temperatures more than 1°C 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 1°C. Image: Sea surface temperature anomaly in 2025. Source: ClimatePulse / Copernicus / ECMWF Ocean temperatures surrounding Australia’s northern tropics were also exceptionally warm early in 2025, with January marking the fourth consecutive month of record-breaking ocean warmth to the north of Australia. Australia’s ocean heat exceeds global anomaly in 2025 Global ocean temperatures were also among the highest on record in 2025 according to data published earlier this month in Advances in Atmospheric Sciences. This study found that the global mean sea surface temperature in 2025 was about 0.49°C above the 1981-2010 average, which was the third warmest year on record. Image: Global annual sea surface temperature anomalies in 2025. Source: ClimatePulse / Copernicus / ECMWF One reason the global ocean temperature didn’t match Australia’s record-breaking warmth in 2025 was because of the cooling effect of La Niña in the tropical Pacific Ocean. La Niña’s cooling influence also helped prevent air temperatures from reaching record highs in 2025, although it was still one of the world’s top three warmest years on record for surface air temperature. - Weatherzone © Weatherzone 2026