August 2026 Chiba Heavy Rainfall Event

Fatalities

13persons

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Cardiac Arrests

2persons

Source: Jiji.com (August 14, 2026)

Missing

1persons

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Injuries

44persons

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Above-Floor Inundation

1,206structures

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Below-Floor Inundation

1,489structures

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Rivers That Overflowed or Exceeded Flood Stages

Ministry of Land, Infrastructure, Transport and Tourism (MLIT) records indicate no flood damage attributable to the overflow of nationally managed rivers (as of August 15–16). Inundation damage was confirmed along 5 prefecturally managed rivers in Chiba Prefecture; however, the names of individual rivers could not be identified from publicly released materials. The primary damage is believed to have resulted not from river overflow but from inland flooding caused by drainage systems being overwhelmed, including flooded roadways and underpasses.

Source: Fukushima no Bosai HIH (compiled from MLIT materials) / MLIT Damage Situation Report No. 5

Maximum 24-Hour Rainfall

364mm

Source: Japan Meteorological Association tenki.jp (August 14, 2026)

Rainfall Records

The AMeDAS station at Chiba (Chuo Ward, Chiba City) recorded 115.0 mm in the one hour ending at 18:48, 188.5 mm over 3 hours, and 293.0 mm over 6 hours — all far surpassing previous records dating back to the start of observations in 1966. All-time records were also broken at Sakura City and Tateyama City. Beginning near Kashiwa City and Abiko City and extending to Ichihara City, Chiba City, Sakura City, Yachiyo City, Inzai City, Yotsukaido City, Funabashi City, and Shiroi City, Extraordinary Heavy Rainfall Advisories were issued in succession. At 19:30 on the 13th, a Special Heavy Rain Warning was issued; at 20:58, a flash bulletin was issued for the development of a Quasi-Stationary Precipitation Band (linear precipitation zone); and at 21:55, a Special Landslide Disaster Warning was issued.

Source: WeatherNews / National Research Institute for Earth Science and Disaster Resilience (NIED), Water and Sediment Disaster Research Division

Landslides

A confirmed total for landslide and debris flow occurrences has not been established. Special Landslide Disaster Warnings (Alert Level 5) were issued for 6 cities including Chiba City and Ichihara City, and slope failures and cliff collapses were reported at numerous locations; however, the total number of incidents remains unconfirmed.

Source: Rescue Now, Inc.

Evacuation Orders

200,000households

Source: Rescue Now, Inc.

Road Closures

4locations

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf