Packing strong winds of 48 meters per second, Typhoon Sanba was moving northward at a speed of 26 kilometers per hour from about 80 kilometers off the southern Japanese island of Okinawa as of Sunday morning, according to the Korean Meteorological Administration.
The massive storm is expected to reach about 70 kilometers off Jeju around 9 a.m. Monday before making landfall in the South Jeolla Province in South Korea's southwest. The typhoon is then expected to move over South Korea's mainland to reach about 90 kilometers from Seoul on Monday night, officials said.
Up to 400 millimeters of rain is expected before it moves out of South Korea, officials said.
As the typhoon approached, Jeju and other southern regions were already receiving rain Sunday.
On Jeju, about 3,000 ships took shelter at ports around the island, ferry services linking Jeju and nearby islands were suspended, and Mount Halla and other areas considered dangerous in such a storm were declared off-limit as precautionary measures.