Japanese weather officials say the Kanto Koshin region, which includes Tokyo, may have heavy rain from Thursday, as atmospheric conditions become very unstable.
The Japan Meteorological Agency says a seasonal rain front will move southward over Japan, while warm moist air will flow in from the south.
The Kanto Koshin region could expect downpours from dawn on Thursday through around Saturday.
Rainfall over a 24-hour period through Thursday evening could total 80 millimeters in northern Kanto and Koshin, and 60 millimeters in southern Kanto.
Koshin could get another 100 millimeters in the next 24-hour period through Friday evening, while southern Kanto could get 80 millimeters, northern Kanto 60 millimeters, and the Izu Islands 50 millimeters.
The rain will likely continue as the pressure pattern will remain largely unchanged. Rainfall in the 24-hour period through Saturday evening will total 100 to 120 millimeters in parts of Kanto Koshin and the Izu Islands.
Agency officials are urging people to be on the alert for landslides, flooding in low-lying areas and river swelling, as well as lightning strikes, sudden gusts of wind and hail.
The rainfall could increase depending on the movements of Tropical Storm Krovanh and the rain front. The agency is urging people to remain updated on the latest weather information.