The South-West Pacific had its second warmest year on record (behind 2024), with extreme weather causing widespread disruption, economic damage, and loss of life.

The deadliest single event of the year in the region was Cyclone Senyar, the first known system to reach tropical cyclone intensity in the Strait of Malacca, which impacted more than 10 million people in Indonesia and Malaysia and killed more than 1200.

The vast ocean expanse in the South-West Pacific is becoming hotter and more acidic, harming local economies and marine ecosystems, whilst rising sea levels threaten vulnerable coastal communities and low-lying island nations, according to the World Meteorological Organization’s (WMO) State of the Climate in the South-West Pacific 2025 report published today.

In 2025, the remaining tropical ice cover in Papua, Indonesia, was estimated to be only about 2% of the ice area observed in 1988. The last remaining tropical glacier of the region is expected to disappear by the end of 2026 or early 2027, according to the report.

“For many countries and territories in the South-West Pacific, the ocean is central to livelihoods, economies and resilience. In 2025, the region experienced warming oceans, rising sea levels, marine heatwaves and ocean acidification, alongside tropical cyclones and the continued loss of tropical glacier ice,” said WMO secretary-general Celeste Saulo. (above pic).

The report includes contributions from National Meteorological and Hydrological Services, climate and ocean experts and United Nations and other international partners. It is one of a series of regional reports by WMO to provide scientific support for climate-smart decision-making and disaster risk reduction.

“Across Asia and the Pacific, heat is intensifying multi-hazard risks, intersecting with food systems, public health, infrastructure and oceans, and placing new pressures on health and livelihoods. Early warning and early action save lives when alerts are timely, messages are trusted and last-mile delivery reaches the vulnerable,” added Armida Salsiah Alisjahbana, executive secretary of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP).

The annual mean surface air temperature averaged over both land and ocean areas in 2025 in the South-West Pacific region ranked as the second highest on record, at about 0.37 °C above the 1991–2020 average.

There were warmer-than-average temperatures in the western Pacific and below-average temperatures over the central tropical Pacific – typical of La Niña conditions.

The WMO added: “As is typical during La Niña conditions, rainfall was above average across much of the Maritime Continent, with many regions recording precipitation within the wettest 10% of years between 1991 and 2020, while much of the western and central equatorial Pacific was drier than average.”

Several countries experienced extreme weather and climate events with fatalities and significant economic losses – especially from tropical cyclones.

Cyclone Senyar was the first tropical cyclone on record in the Strait of Malacca since 1886 and made a first made landfall in northern Sumatra on 26 November before recrossing the Strait and making a second landfall over Peninsular Malaysia. The most extreme rainfall was observed in the far north of Sumatra, Indonesia,  (more than 400 mm in one day), northern Peninsular Malaysia and southern Thailand.

The report includes a case study on impacts and responses on this cyclone. It shows how early warnings, collaboration, and local grants reduced casualties and aided rapid relief. However, there were gaps in last-mile dissemination of warnings to some coastal populations and fishers.

“Cyclone Senyar demonstrated the urgent need for impact-based forecasting of cascading hazards and to prepare for complex scenarios where cyclonic storms combined with monsoon surges trigger simultaneous floods, landslides and debris flows and may even coincide with geophysical hazards such as earthquakes or tsunamis,” it warned.