Japanese weather officials have announced the start of the rainy season in Tokyo and the rest of the Kanto-Koshin region.

The Meteorological Agency said on Monday morning that it expects mostly clouds and rain in the region for the next seven days or so.

The agency said rain is falling from northeastern to western Japan, and rain clouds are developing over limited parts of central Japan and Kagoshima Prefecture's Amami region.

Hourly rainfall of 29.5 millimeters was reported on Yoron Island in Amami.

Intermittent downpours are forecast for the Kanto, Tohoku and Amami regions.

Amami as well as the Izu Islands, south of Tokyo, may have at least 30 millimeters of rain in an hour.

By Tuesday morning, up to 120 millimeters of rain is expected in Kanto-Koshin and Tokai, 100 millimeters in Tohoku and 80 millimeters in southern Kyushu and Amami.

Rain in Tohoku is likely to continue after that.

Weather officials are urging people to stay alert for landslides, flooding in low-lying areas and swollen rivers.