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

Homes with Above-Floor Flooding

1,206structures

Source: 01 被害情報（令和８年８月千葉豪雨）第１４報.pdf

Homes with Below-Floor Flooding

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 inundation was confirmed along 5 prefecturally managed rivers, though individual river names could not be identified from publicly available materials. The primary cause of damage appears to have been not riverine flooding but rather urban inundation (pluvial flooding) caused by drainage systems being overwhelmed, resulting in flooded roads and underpasses.

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

Maximum 24-Hour Rainfall

364mm

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

Rainfall Records

The AMeDAS Chiba station (Chuo Ward, Chiba City) recorded 115.0 mm in 1 hour through 18:48, a 3-hour total of 188.5 mm, and a 6-hour total of 293.0 mm — all by wide margins the highest since observations began in 1966. All-time records were also broken in Sakura City and Tateyama City. Beginning near 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. At 19:30 on the 13th, a Special Heavy Rain Warning was issued; at 20:58, a flash advisory for a linear precipitation band (Senjo Kosuitai) was announced; and at 21:55, a Special Landslide Disaster Warning was issued.

Source: WeatherNews / NIED Water and Sediment Disaster Research Division

Landslides

A confirmed total for landslide and debris flow incidents has not been established. Special Landslide Disaster Warnings (Level 5) were issued for 6 cities including Chiba City and Ichihara City, and reports indicate that slope failures occurred at numerous locations, but the total count remains unconfirmed.

Source: Rescue Now, Inc.

Evacuation Orders Issued

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