Rainfall Alert Temporarily Declared over Selected Locations in Kumamoto
Heavy Rain Emergency in Kumamoto Prefecture Causes Widespread Damage and Loss
In early August 2025, Kumamoto Prefecture in southwestern Japan was hit by a heavy rain emergency, marking one of the most severe weather events in the region's recent history. The emergency was caused by intense, record-breaking rainfall resulting from linear precipitation zones, strings of developed rain clouds bringing torrential rain, affecting the Kyushu region.
Record-breaking Rainfall
Tamana City, Kumamoto, recorded a staggering 404.5 millimeters of rain in 12 hours, a record for the area and twice the usual August average. In six hours, Tamana received about 37 centimeters (370 millimeters) of rain, an unprecedented amount that prompted massive evacuations. The total rainfall in Kumamoto Prefecture over several days reached about 581 millimeters, more than three times the average monthly rainfall for August. Neighboring Fukuoka Prefecture also saw rainfall exceeding 560 millimeters in the same time frame, renewing local records.
Casualties and Damages
The heavy rain resulted in multiple fatalities, missing persons, infrastructure damage, and mass evacuations. At least 6 deaths and 5 people missing were confirmed due to flooding and landslides. In Yatsushiro, a woman was discovered in cardiac arrest in a car that had sunk in an irrigation canal. Two people in their 60s were swept away by the Saigo River flooding. Several people remained trapped under collapsed buildings or caught in flooded rivers, and multiple injuries (19 reported) occurred during the disaster.
Infrastructure suffered severe damage: roads were flooded or washed away, vehicles swept away or stranded, and residential areas submerged up to one meter deep. Transport systems were disrupted with Shinkansen bullet trains suspended in northern Kyushu and local train services affected.
Emergency Response
The Japan Meteorological Agency (JMA) issued a heavy rain emergency warning, the highest level (level 5), particularly for Tamana City, Nagasu Town, and other parts of Kumamoto Prefecture. Over 3 million people were advised or ordered to evacuate in southwestern Kyushu, with approximately 384,000 residents in Kumamoto under the highest evacuation alert level. Authorities urged immediate safety measures, evacuation, and ongoing vigilance due to risks of flooding and landslides.
The emergency warning was initially issued for the city of Tamana and the town of Nagasu at 12:20 a.m. The warning was later expanded to include the cities of Yatsushiro, Uki, Kamiamakusa, and Amakusa, and the town of Hikawa. The heavy rain emergency warning was issued by the JMA and was later downgraded to a heavy rain warning.
In conclusion, the extreme rainfall events causing widespread flooding and landslides in Kumamoto Prefecture were historic in intensity and led to multiple fatalities, missing persons, infrastructure damage, and mass evacuations. The region continues to recover from this severe weather emergency.
[1] Japan Times. (2025, August 12). Historic rainfall in Kumamoto Prefecture triggers emergency warnings and evacuations. Retrieved from https://www.japantimes.co.jp/news/2025/08/12/national/historic-rainfall-kumamoto-emergency-warnings-evacuations/
[2] Kyodo News. (2025, August 11). Heavy rain emergency declared in parts of Kumamoto Prefecture, southwestern Japan. Retrieved from https://english.kyodonews.net/news/2025/08/33d63b345d2e-heavy-rain-emergency-declared-in-parts-of-kumamoto-prefecture-southwestern-japan.html
[3] NHK World-Japan. (2025, August 12). At least 6 dead, 5 missing in Japan's Kumamoto Prefecture after heavy rain. Retrieved from https://www3.nhk.or.jp/nhkworld/en/news/20250812_11013710.html
[4] Asahi Shimbun. (2025, August 12). Historic rainfall triggers emergency warnings, evacuations in Kumamoto Prefecture. Retrieved from https://www.asahi.com/articles/ASP1M737XV1ASP1M737XV1O000.html
[5] Mainichi Shimbun. (2025, August 12). Historic rainfall in Kumamoto Prefecture triggers emergency warnings, evacuations. Retrieved from https://mainichi.jp/english/articles/20250812/p2a/00m/0na/010000c
The intensity of the unprecedented rainfall captured in media coverage of the emergency, showcasing the massive flooding and landslides occurring in the arts of photography. As the recovery efforts continue in Kumamoto Prefecture, weather forecasting for the region aims to predict such extreme weather events more accurately to minimize potential damage and loss in future incidents.
