Japanese weather officials are warning of possible landslides and flooding as atmospheric conditions remain unstable over much of the country.
The Meteorological Agency says warm, moist air is flowing in toward a front and low-pressure system near Japan's main island of Honshu.
Rainclouds are developing, mainly over western Japan.
Kushimoto Town in Wakayama Prefecture had 95 millimeters of rain between 8 and 9 a.m. on Thursday.
Shimonoseki City in Yamaguchi Prefecture had 234 millimeters of rain in the 12-hour period through 5:30 a.m., a record since the agency began taking data there.
Thunderstorms and localized downpours are forecast from northeastern to southwestern Japan.
Northern Kyushu can expect 180 millimeters of rain in the 24-hour period through Friday morning, while the Kinki and Kanto-Koshin regions could have up to 100 millimeters.
Heavy rain has peaked in the northeast and in northern areas along the Sea of Japan, but these regions are prone to landslides as the ground is saturated.
Weather officials are urging caution for landslides, flooding in low-lying areas, swollen rivers, lightning strikes, gusty winds and hail.