Weather officials are warning of heavy rain until Monday for regions along the Sea of Japan coast, from western to northern Japan.
The Meteorological Agency says a rain front that is currently near Kyushu is expected to move north toward the Sea of Japan by Sunday morning.
Authorities also say a low pressure system will form along the front, become more powerful and pass northern Japan through Monday.
Warm and moist air is expected to flow into the front and the low pressure system, making atmospheric conditions unstable mainly along the Sea of Japan coast.
Heavy rain is likely in western Japan until Monday, and in eastern and northern Japan on Sunday and Monday.
Maximum rainfall in the 24 hours through late Sunday afternoon is forecast to reach 150 millimeters in northern Kyushu and 100 millimeters in Chugoku.
In the 24 hours until late Monday afternoon, northern Kyushu is expected to see up to 200 millimeters of rain. Up to 150 millimeters of rain could fall in Chugoku, Tokai, Tohoku and Hokkaido.
The agency is urging people to be on the alert for mudslides, flooding in low-lying areas and rising rivers, as well as lightning strikes and powerful gusts such as tornadoes.