Atmospheric conditions are unstable in the Kanto-Koshin region including Tokyo on Wednesday evening. Rain clouds have developed over Saitama Prefecture, bringing torrential downpours.
Weather officials are warning of flooding on roads and in low-lying areas as well as overflowing of rivers. They are also urging caution against lightning strikes, hail, and violent gusts, including tornadoes.
The Meteorological Agency says warm damp air and rising temperatures are causing the unstable conditions.
Hourly rainfall is believed to have exceeded 100 millimeters in parts of Saitama Prefecture through around 7 p.m.
The rain so far has heightened the risk of landslides in Saitama Prefecture. Landslide alerts are in place in some areas.
Rainfall in the 24 hours through Thursday evening could reach up to 120 millimeters in the northern Kanto region, 100 millimeters in the southern Kanto region, and 80 millimeters in the Koshin region.
Unstable atmospheric conditions are also expected on Thursday.
People are advised to seek shelter in sturdy buildings when there are signs of thunderclouds approaching.