Japan's weather officials are warning of possible landsides and flooding in the southern part of the Kanto region, as torrential rain has softened the ground and sent rivers rising.

The Meteorological Agency says atmospheric conditions are unstable in southern Kanto and the Izu Islands in the Pacific Ocean due to warm moist air flowing into a seasonal rain front stretching near the region.

In Chiba Prefecture, near Tokyo, the city of Minamiboso received 66 millimeters of rainfall over one hour through 1 a.m. on Saturday. Kamogawa City had 53 millimeters of rain between 1 a.m. and 2 a.m.

The rain front is expected to move south, bringing possible localized heavy rain with thunder to the Izu Islands through Saturday noon. This area could see more than 30 millimeters of rain per hour.

During the 24-hour period through Sunday morning, up to 100 millimeters of rain is forecast for the islands.

Officials are calling on people to stay alert to the risks of landslides and overflowing rivers. They are also urging caution regarding possible lightning strikes and violent wind gusts like tornadoes.