Record-breaking rainfall in eastern Japan has killed at least eight people, injured more than 30 and stranded thousands of travellers as authorities described the weather as “unprecedented.” More than 360 millimetres, or 14 inches, of rain fell within 24 hours in parts of Chiba Prefecture, immediately east of Tokyo, overwhelming roads, railway lines, drainage systems and homes during the busy Obon holiday period.
The Japan Meteorological Agency (JMA) said warm, humid air colliding with colder air above created extremely unstable conditions. Chiba recorded more than 100mm of rain per hour from Thursday afternoon, while one area received around 115mm in a single hour, roughly three times its average rainfall for the entire month of August and the highest hourly precipitation volume ever recorded in Japan.
Authorities issued a level five emergency warning, Japan’s highest alert, for heavy rain and landslides in parts of Chiba on Thursday. It was lowered to level four by Friday morning, August 14, but flooding, swollen rivers and landslides remained serious risks.
Chiba Governor Toshihito Kumagai called the situation “extremely unusual” and said saving lives remained the priority. One woman was found dead inside a submerged car, while others collapsed in the streets and later died. One person remained missing. Japan’s Ground Self-Defense Force was deployed to assist rescue and evacuation operations, including in Oamishirasato and Kashiwa city.
More than 100,000 households were asked to evacuate on Thursday. Thousands stayed at hundreds of evacuation centres, including around 1,800 people who sheltered overnight at the Chiba Prefectural Government building. In Ichikawa, one resident told NHK that the rain arrived suddenly while a power outage left her uncertain about reopening her business.
At Tokyo’s Narita Airport, approximately 7,000 passengers were stranded overnight after flooding disrupted transport connections. Airport staff distributed sleeping bags, water and snacks. Chiba resident Minoru Yamasaki, 48, said he waited four hours for a taxi before returning to the airport after a hotel he had booked turned him away.
Flights were expected to operate largely normally on Friday, with Japan Airlines anticipating possible delays but no cancellations. Several rail services between Narita and Tokyo partially resumed, although major highways remained closed.
Tokyo Electric Power Company (TEPCO) reported more than 20,000-22,000 households without electricity after floodwater affected a substation, while gas supplies to nearly 13,000 households were temporarily cut.
The emergency comes during an unusually active East Asian typhoon season involving Typhoon Dolphin, Tropical Storm Chan-hom and Typhoon Peilou. Dolphin later became China’s strongest typhoon of 2026, forcing more than 300,000 people to relocate and causing Shanghai to cancel over 1,300 flights.
Scientists warn warmer air can hold more moisture, increasing extreme rainfall risks as the climate changes. Although Chiba’s heaviest rain eased Friday morning, rescue and recovery operations continued, with authorities warning residents to remain alert for further flooding and landslides.
