Typhoon Dujuan brought record-breaking rainfall to parts of eastern Japan, dumping 832 millimetres of rain on Izu Oshima island in just 48 hours. Tokyo's Edogawa ward also recorded its highest-ever 24-hour rainfall.
The storm left at least four people dead, six missing and 22 injured. More than 1.6 million people were urged to evacuate, while torrential rain triggered flooding and landslides across the region. But what made the rainfall so intense?
In this video, we explain how warm ocean waters fuel typhoons, why September remains a wet month in Japan, and how Dujuan's moisture interacted with the country's autumn rain front to intensify rainfall. As another tropical system threatens Taiwan, what does this mean for the region's storm season?