Typhoon Ma-on on Friday was moving northward off Minamidaito Island in Okinawa as it gathered strength for what is expected to be the most powerful storm to hit the Kanto region in a decade, the Meteorological Agency said.
The agency said the typhoon will strike the Kinki and Kanto regions Saturday and warned of heavy rain, high winds and sea surges.
The center of Typhoon Ma-on is likely to pass by Honshu and reach an area off the Sanriku region in northeastern Japan on Sunday, it said.
"Ma-on," the Cantonese word for saddle and the name of a peak in Hong Kong, would be the ninth typhoon to land on Japan this year -- a record high, the agency said.
The storm is likely to produce rain clouds in the Shikoku and Tokai regions mainly off the Pacific coast, while heavy rain is expected across the Tohoku region.
As of 8 p.m. Friday, the typhoon was about 200 km east-northeast of Minamidaito Island and moving north-northeast at 30 kph. It was packing winds of up to 180 kph near its center and had an atmospheric pressure of 920 hectopascals.
Minamidaito is about 400 km east of Naha, Okinawa.