Kyushu flooding
south Japan

1-5 July 2019

Kyushu, Japan’s third largest and most south-westerly island, has been affected by wide-scale flooding and deadly landslides over the past week. The impact has caused widespread disruption to millions of residents, as well as affecting businesses and transport networks across the region.

For the 2020 flood event, please read our latest event commentary.

What caused the flooding?

The flooding, which affected southern Japan, was caused by a weather system front known as the mei-yu front (also known as the baiu front). This phenomenon is the result of a persistent, nearly stationary, east-west weak baroclinic zone which is in the lower troposphere and stretches from eastern China through Taiwan and across southern Japan into the Pacific Ocean (American Meteorological Society, 2012). It is a weather system which typically forms during mid to late spring and then continues through to midsummer. The front plays an integral role in many of the weather and climatic systems across a large part of Asia, especially in the south east of the region, bringing warm moist air from the South China Sea and the Bay of Bengal. On this occasion, the weather front stalled over the south of Kyushu island causing heavy and persistent rainfall (NPR, 2019). 

Impact to locals

The wide-scale reach of the heavy rain broke numerous meteorological records across the region, previously set in October 2017. Several prefectures such as Miyazaki and Kagoshima have experienced the highest levels of rainfall since records began. The city of Ebino in Miyazaki Prefecture saw over 381mm of rainfall within three days, whilst Nichinan in the same prefecture saw over 554mm (Floodlist, 2019; Accuweather, 2019). The cities of Kirishima and Hioki, both in the Kagoshima Prefecture, experienced 241.5mm and 233mm worth of rain within a six-hour window (Japan Times, 2019).

The relentless rainfall has heavily saturated large areas of land in upland areas, triggering deadly landslides which have claimed the lives of two individuals in Kagoshima Prefecture (Washington Post, 2019). The heavy band of rain has caused widespread disruption to over 1.1 million residents on the island of Kyushu, mainly in the Kagishima, Miyazki, Kumamoto and Ishikawa prefectures. The country’s Fire and Disaster Management Agency has reported that by 3 July more than 925,435 residents in Kagoshima Prefecture and 27,227 in Miyazaki Prefecture were put under evacuation orders due to heavy rain and the potential threat to life from flash flooding and landslides (Independent, 2019).

The heavy rain has affected the transport system within the region and sections of the high-speed Kyushu Shinkansen bullet train line were disrupted for several hours. Over a hundred schools and small businesses were also forced to close (Kyodo News, 2019).


Further heavy rain is set to continue, along with strong winds and thunderstorms, as a new wave of significant rainfall looks to have moved in from the East China Sea, bringing more disruption to Kyushu, the southern mainland of Honshu and the island of Shikoku.

JBA Risk Management has nationwide return period flood maps for Japan at 30m resolution. Please get in touch for more information.


AccuWeather. 2019. Japan braces for more rain after deadly rain, flooding last week. [online] Available at: [Accessed 11 July 2019].

American Meteorological Society. 2019. Glossary of Meteorology: Mei-yu front. [online] Available at: [Accessed 11 July 2019].

FloodList. 2019. Japan – 1 Million Ordered to Evacuate After Torrential Rain in Kyushu. [online] Available at: [Accessed 11 July 2019].

Independent. 2019. Japan evacuation: More than 1m people ordered to flee as torrential rains batter Kyushu island. [online] Available at: [Accessed 11 July 2019].

Japan Times: 2019. Heavy rains prompt evacuation orders in Kagoshima as weather agency warns of mudslides and floods. [online] Available at: [Accessed 11 July 2019].

Kyodo News. 2019. Downpours trigger flooding, 1.1 mil. asked to evacuate in Japan. [online] Available at: [Accessed 11 July 2019].

NPR. 2019. Heavy Rains Force Evacuation Orders For More Than 1 Million People In Japan. [online] Available at: [Accessed 11 July 2019].

Washington Post. 2019. Heavy rain in Japan causes flood, mudslides, blackout. [online] Available at: [Accessed 11 July 2019].