Downpours have been hitting parts of the Kanto and Tohoku regions due to a front. Weather officials are warning of more rain, saying that bands of heavy rain clouds may develop over the Tokai region and the Izu Islands.
Japan's Meteorological Agency says extremely unstable atmospheric conditions have formed from western to northern Japan because of warm and damp air flowing into the front.
Ibaraki Prefecture's Hitachiomiya City, Kanto region, had about 52.5 millimeters of rain in the hour through 5:00 p.m. on Wednesday.
In Miyagi Prefecture's Ishinomaki City in the Tohoku region, 155.5 millimeters of rain fell in the 12 hours through 6 p.m. That is more than the typical amount of rainfall for the entire month of September.
The front is expected to move over the main island of Honshu through Thursday morning. Heavy rain and thunder are expected through Wednesday night in northern and western Japan, and through Thursday morning in eastern Japan. Localized torrential downpours are likely in eastern Japan.
Officials say bands of heavy rain clouds may form over the Tokai region and the Izu Islands through Thursday morning, which could sharply heighten the risks of disasters.
Weather officials are warning of mudslides, floods in low-lying areas and swollen rivers, lightning strikes, tornadoes and strong gusts.
Separately, Tropical Storm Yun-yeung is moving northward over the sea south of Japan. It may approach eastern Japan from Thursday through Saturday. Officials are calling on people to tune into the latest information.