Typhoon Ketsana formed in the Pacific and made landfall in the Philippines, specifically impacting the capital city of Manila and surrounding provinces. The storm brought extraordinary rainfall, causing rivers to overflow and rapid urban flooding. The Philippine National Disaster Coordinating Council reported over 400 millimeters of rainfall in just 24 hours, a figure that contributed to the immense destruction. Significant infrastructure was damaged, including roads, bridges, and schools, while numerous communities faced evacuations due to rising waters. Residential areas were submerged, and access to clean water became a critical concern following the storm.

After affecting the Philippines, Ketsana continued its trajectory across Southeast Asia, impacting countries like Vietnam, Cambodia, Laos, and Thailand. Each of these nations experienced severe rainfall, with flooding that further exacerbated the humanitarian crisis initiated in the Philippines. In Vietnam, the storm caused landslides and additional fatalities. International relief efforts were mobilized swiftly as the scale of devastation became evident, with both local and global organizations stepping in to provide support. The typhoon underscored the vulnerabilities of both urban and rural communities in the region to natural disasters, prompting discussions about preparedness and disaster response strategies.

In the aftermath, long-term recovery programs were implemented, focusing on rebuilding infrastructure and addressing food security issues exacerbated by the typhoon. The storm's significant impact raised awareness about climate change and the increasing frequency of natural disasters, resulting in advocacy for improved forecasting and emergency response systems across Southeast Asia.