- Date:
- November 2025 - December 2025
Asia Floods of 2025
Which countries were affected by the 2025 Asia floods?
What caused the severe flooding in Southeast Asia in 2025?
What was the impact of flooding in Indonesia in November 2025?
What climatic factors contributed to the Asia floods of 2025?
Several South and Southeast Asian countries witnessed destructive flooding in November and December of 2025, causing tragic loss of life, widespread displacement, and severe infrastructure damage that strained national economies and disaster-response systems. In Sri Lanka, Indonesia, Thailand, Malaysia, the Philippines, and Vietnam, successive, frequent, and unusually intense monsoon conditions and cyclones produced catastrophic impacts, killing more than 1,600 across all affected regions. This season also witnessed the rare development of Cyclonic Storms Ditwah and Senyar in typically inactive regions, with Senyar marking the first cyclonic storm to form in the Strait of Malacca in 135 years.
Widespread destruction
An erratic northeast monsoon (a seasonal wind system that travels through Southeast Asia and brings rainfall to the region as well as southeastern India and Sri Lanka) was strengthened by several storms that coincided with it, bringing torrential rainfall and major floods to South and Southeast Asia. Indonesia experienced disruption, as an estimated 1.5 million people were affected, 570,000 were displaced, and approximately 700 died. Vietnam recorded at least 90 deaths during November alone, in addition to 10 deaths recorded the previous month. The situation in Vietnam was worsened by typhoons that struck between September and November—Ragasa, Bualoi, Matmo, and Kalmaegi—each compounding the damage of the last. The weather conditions created by the passage of Cyclonic Storm Ditwah affected more than 1 million people in the South Asian country of Sri Lanka, where roughly 15,000 homes were destroyed and about 500 people were killed.
Flooding and landslides in Thailand caused at least 160 deaths and displaced roughly 2 million people. The Philippines saw the passage of several typhoons and super typhoons, starting with Super Typhoon Ragasa in September. The damage from that storm was not fully fixed when Typhoon Kalmaegi and Super Typhoon Fung-wong made landfall in the island country roughly five days apart in early November. About 265 people died as heavy rainfall, high winds, and secondary hazards affected communities across the country.
Cyclones, cyclonic storms, and typhoons
Typhoons and cyclones in the northwestern Pacific Ocean, the South China Sea, and the Indian Ocean were frequent and intense in the last quarter of 2025. In addition to the series of typhoons that struck the Philippines and Vietnam between September and October, November continued the active storm season.
Cyclonic Storm Ditwah formed as a tropical depression south of Sri Lanka on November 24. Concurrent with the Indian Meteorological Department storm scale used in the area, the system was designated a cyclonic storm on November 27. The storm’s top sustained wind speed hovered about 40 miles (65 km) per hour, a moderate wind speed for a cyclonic storm, but it became one of the most devastating natural disasters the island country’s history. The waters around Sri Lanka seldom give rise to circular storms of the scale requisite for the formation of cyclones, so its disaster-response systems are not equipped to mitigate the impact of major storms such as Ditwah.
A depression system formed in the Philippines on November 24 and moved westward. Following the storm classification system observed by weather monitoring entities in the region, the system intensified into a typhoon on the evening of November 26 over the waters of the South China Sea. The system, designated Koto, continued to interact with local monsoon conditions and with a cyclone system to the southwest until it dissipated over open waters to the east of Vietnam on December 3.
On November 25 a depression system that formed in the Strait of Malacca intensified into a deep depression and unexpectedly strengthened into a cyclonic storm the next day despite being less than five degrees of latitude north of the Equator, a geographical extent not commonly conducive to the formation of cyclones. This made the system, designated Senyar, the first designated cyclonic storm in the Strait of Malacca in 135 years. Though a weak cyclonic system, Senyar nevertheless caused severe flooding in Indonesia and caused more than 400 deaths as it looped from an easterly to a westerly direction through northern Sumatra and traveled eastward as a deep depression. The system interacted with the Ditwah system early in its path and with Typhoon Koto in the South China Sea toward the end of its course. The interaction of the outer winds of these systems caused wide-ranging weather anomalies that added to the erratic northeast monsoon in South and Southeast Asia.
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- La Niña is a weather event involving the cooling of eastern Pacific Ocean surface waters. The global impact of this cooling is the warming of Pacific waters near Asia, which creates conditions conducive to the growth of typhoons.
- Wind shear is a rapid change in wind velocity or direction. It is observed both near the ground and in jet streams. Vertical wind shear in particular involves rapid changes in wind speed and direction as altitude increases.
Climatic extremes and anomalies
The exceptional flooding and storm activity of November 2025 occurred amid climatic anomalies across the Indo-Pacific region. The continued increase of temperatures the world over due to global warming formed the backdrop of these phenomena. Warmer air, which holds more moisture and increases the likelihood of extreme rainfall, contributed to an unusually moisture-rich northeast monsoon. As the monsoon system moved across the region, it delivered exceptionally heavy precipitation.
A strengthening La Niña made the atmosphere over South and Southeast Asia more conducive to storm formation. The warmer temperatures produced by this phenomenon also reduced vertical wind shear in several tropical basins, thereby removing one of the factors that controls the formation of tropical cyclones. The resulting storms overwhelmed urban drainage systems, reservoirs, and flood-control works in many countries.
Preexisting economic and environmental vulnerabilities also amplified the effects of these climatic extremes. Many of the affected countries were grappling with weakened economies that undermined their disaster preparedness. In regions such as Sumatra, extensive deforestation removed natural buffers that once slowed soil runoff and reduced the severity of floods. The anomalous monsoon underscored the significant change in climatic trends and the need for the affected countries to dramatically reassess their disaster preparedness.