The storm, which had Tuesday passed over the Japanese island of Okinawa, was the strongest to hit the Seoul metropolitan area for 15 years.
It reached the west coast of South Korea early Thursday and was expected to move to the Sea of Japan (East Sea) in the afternoon.
Most above-ground sections of Seoul’s extensive subway network were out of service because of power cuts, and drivers and pedestrians had to contend with toppled trees and strong winds.
The National Emergency Management Agency said four people were reported injured as of 8am. Yonhap news agency said an 80-year-old man at Seosan in South Chungcheong province had died after being hit by a flying roof tile.
The Seoul education office asked elementary and middle schools in the capital to delay the start of classes by two hours. All public and private kindergartens were ordered closed for the day.
All flights were cancelled before 9am Thursday at Gimpo International Airport in Seoul, officials said. Incheon International Airport west of the capital cancelled or diverted nearly 40 domestic or international flights.