Typhoon Dujuan, also designated as Typhoon 25, caused severe flooding and landslides in Japan’s Kanto region last month, resulting in 14 confirmed fatalities across Chiba and Kanagawa prefectures. As of September 28, nine deaths were reported in Chiba Prefecture and five in Kanagawa Prefecture.

The storm brought extended periods of heavy rain, producing record-breaking accumulations in many areas. According to the Japan Meteorological Agency, some locations in Chiba Prefecture experienced rainfall totaling more than 480 millimeters over 48 hours through the night of September 21. Otaki recorded 489 millimeters, and Ichihara reported 487 millimeters. In Chiba City’s Chuo Ward, rainfall reached 419 millimeters during the same period.

These amounts substantially exceeded those recorded during previous torrential rains in August, which saw a maximum 48-hour total of 387 millimeters in Chuo Ward. While August’s rains featured intense hourly downpours—up to 115 millimeters—the typhoon’s peak hourly rainfall was lower, with 61 millimeters recorded in Katori, also in Chiba Prefecture. Unlike the August event, typhoon-related rainfall occurred intermittently over several days, rather than in concentrated bands.

Meteorological officials noted that the prolonged inflow of warm, humid air associated with the typhoon sustained the rainfall from September 19 onward, contributing to the unusually high totals. This extended wet period likely weakened slopes and soils, increasing the risk of landslides.

Takehiko Yamamura, director of the Disaster Prevention System Institute in Tokyo, indicated that the sustained rainfall may have saturated the ground, triggering landslides in vulnerable areas. He advised residents to heed warnings and consider evacuation promptly when a Level 3 Warning, which signals increased danger, is issued—especially for those in landslide-prone zones.

The impacts of Typhoon Dujuan underscore the continued vulnerability of the Kanto region to extreme weather events and highlight the importance of timely disaster preparedness and response measures. Authorities continue monitoring affected areas and are engaged in recovery and support operations for communities impacted by the typhoon.