August 2026 Chiba Heavy Rainfall

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

Inundation Above Floor Level

1,206structures

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Inundation Below Floor Level

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 Stage

According to Ministry of Land, Infrastructure, Transport and Tourism (MLIT) documents, no flood damage was reported from nationally managed rivers (as of August 15–16). Flood damage was confirmed along 5 prefectural-managed rivers, however individual river names could not be identified from publicly available documents. The primary driver of damage appears to have been not riverine flooding but rather inundation caused by drainage systems being overwhelmed (surface flooding of roads, underpasses, etc.).

Source: Fukushima no Bosai HIH (compiled from MLIT documents) / 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 1 hour ending at 18:48, 188.5 mm over 3 hours, and 293.0 mm over 6 hours — all by wide margins the highest on record since observations began in 1966. All-time records were also broken at Sakura City and Tateyama City. Beginning in the vicinity of Kashiwa City and Abiko City, Extreme Hourly Rainfall Alerts were issued for Ichihara City, Chiba City, Sakura City, Yachiyo City, Inzai City, Yotsukaido City, Funabashi City, and Shiroi City. A Special Heavy Rain Warning was issued at 19:30 on the 13th, a Quasi-Stationary Convective Band (linear precipitation zone) formation bulletin was issued at 20:58, and a Special Landslide Disaster Warning was issued at 21:55.

Source: WeatherNews / 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 (Level 5) were issued for 6 cities including Chiba City and Ichihara City, and slope failures were reported at multiple locations, but the exact 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