Overview:
Satellite data show sea surface temperatures rising sharply across parts of the southwest Pacific, triggering strong to severe marine heatwave conditions around Tonga, Fiji and Niue. Scientists warn the prolonged warming could impact marine ecosystems, fisheries and coastal communities if conditions persist.
SUVA, 02 FEBRUARY 2026 (SPC)—Recent satellite data show that sea surface temperatures have risen significantly across parts of the southwest Pacific Ocean, particularly around Tonga, Niue, and Fiji.
As of January 21, 2026, ocean temperatures in southern Tonga were 3 to 4°C above normal, while waters around Fiji and west of Niue’s Exclusive Economic Zone (EEZ) were 2 to 3°C above normal. These unusually high ocean temperatures may be connected to recent reports of dead fish in Tonga, though further investigation is needed to confirm the cause.
Over the past few days, Tonga has also experienced light winds, fewer clouds, very low swells from the north and strong direct sunlight – the sun reached its zenith above Tongatapu during this time, which may have contributed to the warming.
According to the National Oceanic Atmospheric Administration (NOAA) Coral Reef Watch Daily Marine Heatwave report issued on the same date, Fiji and Niue are currently experiencing a strong marine heatwave, while Tonga is facing strong to severe conditions. Marine heatwave maps for each country are available on the Pacific Ocean Portal.
Looking ahead, the Australian Bureau of Meteorology’s two-week outlook suggests that strong marine heatwave conditions are expected to continue through 2 February, particularly for Tonga. Moderate heatwave conditions are likely across much of the Pacific during February, with severe conditions forecasted for parts of the Federated States of Micronesia (FSM) and Papua New Guinea (PNG). As this is a monthly outlook, day-to-day and weekly conditions may vary.
The latest Coral Bleaching Alert (22 January) shows that most areas are under a bleaching warning, with a few patches of Alert Level 1 conditions observed in part of PNG, southwestern Samoa, and southern Tonga.
Authorities and stakeholders are encouraged to continue monitoring conditions closely, as prolonged periods of high sea surface temperatures can affect marine ecosystems, fisheries, and coastal communities. Any observed or experienced impacts should be reported to the National Meteorological Office to support ongoing monitoring and improvement of marine. …PACNEWS