Typhoon Trami is battering Okinawa Prefecture and the Amami Islands in Japan's south, as it churns north toward the country's main islands. It could possibly make landfall on the western and eastern main islands on Sunday, NHK reported.
Weather officials are calling on people across Japan to take early precautions.
The Meteorological Agency said that at 9 PM on Saturday, the very strong storm was about 60 kilometers west of Okinoerabu Island in Kagoshima Prefecture, and was moving north-northeast at a speed of 25 kilometers per hour.
It has a central atmospheric pressure of 950 hectopascals and is packing winds of up to 162 kilometers per hour near its center.
The maximum instantaneous wind speed topped 191 kilometers per hour in the city of Naha at 6:15 PM, and 185 kilometers per hour in the town of Amagi, Kagoshima Prefecture, at 6:16 PM.
Violent winds from the slow-moving typhoon are expected to continue in Okinawa and Amami till Sunday.
The islands may receive more than 80 millimeters of rain an hour.
Weather officials forecast up to 400 millimeters of rain for Amami, and up to 200 millimeters for Okinawa in the 24 hours through Sunday evening.
Trami is predicted to gain speed as it heads northeast. It is expected to maintain its strength as it nears Japan's west and east on Sunday.
The storm is expected to pass over eastern and northern Japan between Sunday and Monday.
Weather officials are calling on people across Japan to stay alert through Monday for heavy rains, strong winds and rough seas.