More heavy rains are expected in parts of Japan, including Kyushu and Tokai, which have already been hit by record rainfall.
The Meteorological Agency says warm, damp air is flowing towards a seasonal rain front hovering around the Japanese archipelago, destabilizing atmospheric conditions. Rain clouds are developing in northern Kyushu and the Chugoku region.
Hourly rainfall of about 40 millimeters was observed in Soeda Town, Fukuoka Prefecture, and over 36 millimeters in Tosu City, Saga Prefecture.
Some rivers in Yamaguchi and Hiroshima prefectures are at risk of overflowing. The risk of landslides has increased in parts of Fukuoka, Oita, Yamaguchi and Hiroshima prefectures.
A low-pressure system is forecast to move eastward over the Sea of Japan, bringing thundery downpours to parts of western and eastern Japan.
Kumamoto Prefecture, which has already been battered by record rainfall, may see hourly rainfall of 70 millimeters.
For the 24-hour period through Tuesday evening, up to 250 millimeters of rain are expected in Tokai: 200 millimeters in northern Kyushu and Shikoku; 180 millimeters in Hokuriku; and 150 millimeters in southern Kyushu and the Chugoku, Kansai and Kanto Koshin regions.
The rains are expected to continue into Wednesday.
Agency officials are warning of landslides, swollen rivers, and floods in low-lying areas, as well as lightning and strong wind gusts.