Heavy rains in the northern part of Japan's Kyushu island are threatening the territory with landslides and flooding.

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 52 millimeters was observed in Hita City, Oita Prefecture, and 46 millimeters in Kikuchi City, Kumamoto Prefecture.

Parts of the Chugoku region, including Hiroshima Prefecture, have had nearly 200 millimeters of rain in the past 24 hours.

Some rivers in Fukuoka, Yamaguchi and Hiroshima prefectures are at risk of overflowing. The risk of landslides has increased in parts of Fukuoka, Oita, Yamaguchi, Hiroshima, Okayama and Shimane 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.