Cyclonic storm Ditwah causes catastrophic flooding in Sri Lanka
In late November 2025, a cyclonic storm known as “Cyclone Ditwah” emerged from the warm waters of the Bay of Bengal and made landfall on the eastern coast of Sri Lanka on 27 November 2025 just before 12:00 UTC (ReliefWeb, 2025a). The landfall unleashed torrential rainfall, widespread flooding, and deadly landslides that overwhelmed communities across 25 districts (UNFPA, 2025; WHO, 2025).
In just eight to nine days, about one-fifth of Sri Lanka became inundated, with 2.3 million Sri Lankans affected, of whom more than 60% were from Colombo and Gampaha (UNDP, 2025). As of 11 December 2025, more than 600 fatalities were reported, with economic losses reaching around US$7 billion (The Straits Times, 2025). The impact of Cyclone Ditwah was reported as one of the fastest crises to unfold in a short span of time (UNDP, 2025).
Overview and timeline
Cyclone Ditwah began as a well-marked low-pressure area just off the south-eastern coast of Sri Lanka on 26 November 2025. As the system moved into the Bay of Bengal, it encountered atmospheric and oceanic conditions allowing it to rapidly intensify into a tropical depression.
By the next day, the system had strengthened and developed into Cyclone Ditwah, making landfall with maximum sustained winds of approximately 65 km/h. The cyclone continued its passage northward inland and centred over northern Sri Lanka on 28 November 2025 (06:00 UTC), maintaining sustained winds of 65 km/h (ReliefWeb, 2025a). It continued northward over the Bay of Bengal until 29 November 2025 (20:00, UTC), where it slightly weakened and was reduced to a tropical depression on 30 November 2025 (Zoom Earth, 2025).
This cyclone formation occurred right in the heart of the “Maha” season (September-March), which coincides with the Northeast Monsoon. This season is characterised as one that brings heavy rainfall to the northern and eastern parts of Sri Lanka (FAO). While the “Maha” season is important for agriculture, such as replenishing the water reservoirs and supporting crop growth of staples like rice to sustain the population (Lanka Tour Experts), it also increases the vulnerability to flooding, strong winds, and storm-related hazards.
According to the Department of Meteorology’s report on 28 November 2025, the observed 24-hour rainfall for several districts exceeded 300mm, which includes Vavuniya, Nuwara Eliya, Kandy, Anuradhapura, and Mullaitivu (Disaster Management Centre, 2025). A local hydrology professor estimated the rainfall received on this day as nearly 10% of Sri Lanka’s annual average landfall which has significantly strained the catchments’ capacity (The Diplomat, 2025).
Impact
Cyclone Ditwah’s passage through Sri Lanka resulted in one of the most severe natural disasters to affect the island in decades. Geospatial analysis from the United Nations Development Programme (UNDP) shows about 1.1 million hectares were submerged, and floodwaters reached nearly 720,000 buildings and over 16,000 kilometres of roads. In the more hill-bound areas, around 1,200 landslides were triggered, isolating at-risk communities by disrupting access to essential services (UNDP, 2025).
Central Sri Lanka was particularly hit hard, threatening Sri Lanka’s tea and vegetable industry. The cyclone-induced floods and landslides uprooted many fully grown tea plantations, destroying roads and railway lines, and delaying the delivery of essentials, thereby rendering thousands of plantation workers homeless (Al Jazeera, 2025). As the second largest source of export revenue, preliminary estimates predict an output decline of about 35% for the tea industry in Sri Lanka.
As of 12 December 2025, the Disaster Management Centre reported that 5,588 houses were completely destroyed, 87,496 sustained partial damage, and 866 evacuation centres were established to accommodate 84,674 displaced individuals (ReliefWeb, 2025b).
Government officials have estimated a significant economic loss at USD$6-7 billion, which is nearly 3-5% of the nation’s Gross Domestic Product and surpasses the country’s foreign reserves (The Diplomat). This prompted the government to make a request to International Monetary Fund (IMF) of US$200 million for disaster recovery and support (Institute of South Asian Studies, 2025).
Notable historical events
Sri Lanka and the broader Bay of Bengal region have a long history of weather-related disasters driven by cyclones, monsoons, and extreme rainfall events. Although direct cyclone landfalls on Sri Lanka are extremely rare, the island has experienced severe flooding, landslides, and storm-related damage from systems that formed in the same basin as Cyclone Ditwah.
Climate change
Cyclone Ditwah occurred during the Maha season, when background conditions in Sri Lanka are already favourable for prolonged rainfall and elevated flood risk. In this context, climate change is relevant primarily through its influence on extreme precipitation rather than on cyclone frequency or intensity. Warmer atmospheric conditions increase the capacity of the air to hold moisture, which can intensify rainfall when weather systems develop.
The World Weather Attribution team analysed recent extreme rainfall and flooding in Sri Lanka and found evidence of an increase in extreme five-day rainfall totals associated with approximately 1.3 °C of global warming to date (World Weather Attribution, 2025). However, their analysis also highlights substantial uncertainty, including limited agreement across climate models, which prevents a robust quantitative attribution of the observed rainfall changes, and therefore the resulting flood impacts, directly to climate change. The study further notes that large-scale climate variability, including ENSO and Indian Ocean Dipole conditions, as well as local exposure and vulnerability, play an important role in shaping flood outcomes.
For Cyclone Ditwah, this implies that while physical mechanisms linking warming to heavier rainfall are well established, the severity of flooding resulted from a combination of meteorological conditions, seasonal hydrological stress, and local catchment and infrastructure characteristics. Climate change may have increased the likelihood of intense rainfall, but it is not possible to isolate its contribution to the observed impacts for this event alone.
Conclusion
Cyclone Ditwah was a moderate cyclonic system that nonetheless produced widespread flooding across Sri Lanka during the Maha season, illustrating how seasonal rainfall patterns and hydrological conditions can amplify impacts even in the absence of extreme cyclone intensity. The event underscores Sri Lanka’s sensitivity to prolonged heavy rainfall, particularly when rivers, reservoirs and soils are already close to capacity.
As climate change continues to influence rainfall extremes, future flood risk in Sri Lanka will depend not only on changes in hazard but also on exposure, vulnerability, and preparedness. Strengthening early warning systems, improving drainage and river management, and incorporating flood risk into infrastructure and land-use planning remain key measures for reducing future losses. Cyclone Ditwah provides a recent example of how these factors interact, offering lessons for managing flood risk under both current and evolving climate conditions.
This report is accompanied by a flood footprint for the event, detailing extents and depths of the flooding in areas affected in Sri Lanka. Download it via our Client Portal or request a copy by emailing eventresponse@jbarisk.com.
