Typhoon Sanba, packing winds of 155 kilometres (97 miles) per hour, slammed into South Korea Monday, bringing torrential rains across the country and shutting down flights and ferry services.
Sanba -- the third major typhoon to hit the Korean peninsula in two months -- made landfall at the southern port of Yeosu shortly before midday (0300 GMT).
Moving at around 35 kilometres per hour, the typhoon had pounded the South Korean island of Jeju overnight Sunday, leaving around 10,000 homes without power and damaging road networks.
There were no immediate reports of any casualties.
As it crossed southwestern Japan on Sunday, the typhoon had earlier claimed one life and cut power to 100,000 households.
"Although its power is diminishing due to the low sea temperature, and is expected to diminish even more after making landfall, it's still a powerful typhoon," said a spokesman for the Korea Meteorological Administration.
Seoul authorities warned of heavy rainfall of nearly 300 millimetres (12 inches) in Jeju and southern coastal regions from Sunday to Monday night.
Severe storm alerts have been issued in southern regions, with the warnings likely to expand to the rest of the country in the afternoon, they said.
The typhoon is expected to move northeast across the peninsula and back out to sea over the North Korean port of Chongjin.
More than 200 flights -- mostly domestic -- and all 88 ferry services across South Korea have been cancelled since Sunday, the transport ministry said, adding some 2,000 ships have been taken out of the storm's path.
About 1,100 residents in areas deemed vulnerable have been taken to shelters, the National Emergency Management Agency said, while another 12,000 residents in other areas have been advised to evacuate.
Tens of thousands of officials have been on high alert, carrying out special inspections on the entire 15 airports across the nation. Thousands of schools in southern regions remained closed Monday.
Typhoons Bolaven and Tembin, which struck the peninsula in late August, left more than 20 people dead in the South, damaging farmland and hundreds of houses and causing power cuts that affected millions of homes.
North Korea's state media said Bolaven -- the strongest typhoon to hit the peninsula for almost a decade -- killed 59 people and left more than 26,000 people homeless.