Japanese weather officials say the rainy season appears to have begun in the northern part of western Japan's Kyushu region. They are also warning of landslides, flooding of low-lying land and swelling rivers in southern Kyushu and Shikoku.
The Meteorological Agency said on Monday heavy rain was pounding southern Kyushu and Okinawa Prefecture on and off. It said rainy and cloudy weather is predicted to continue mainly in Kyushu, announcing the start of the rainy season in northern Kyushu.
The announcement for the region is 13 days later than usual and 19 days later than last year.
Weather officials also say a front lying off Japan's Pacific coast is expected to get active, likely bringing thunderstorms to regions between the Nansei Islands and eastern Japan through Tuesday.
The officials say bands of rain clouds may unleash large amounts of rain in the prefectures of Miyazaki and Kagoshima, excluding Amami, from Monday night to Tuesday morning. They say bands of rain clouds may also form over four prefectures in Shikoku on Tuesday morning. That could sharply raise the risk of disasters.
During the 24-hour period until Tuesday noon, up to 300 millimeters of rain is forecast for southern Kyushu and Shikoku; 180 millimeters for Amami and Kansai; 150 millimeters for northern Kyushu and Tokai; and 120 millimeters for Okinawa and Kanto-Koshin.
In the next 24-hour period through Wednesday noon, 120 millimeters of rain is expected in Tokai and Kanto-Koshin.
The Meteorological Agency is urging caution against landslides, flooding in low-lying areas, swelling rivers, lightning, gusts and hailstorms.
It is also calling on people to take safety measures, including moving into sturdy buildings, if there are any signs of developed thunderclouds approaching.
People in areas where heavy rain is expected are advised to check local hazard maps in advance and confirm the latest information to evacuate early.