Sanba came on the heels of Typhoon Bolaven, which killed dozens of people and inflicting heavy damage in both South and North Korea late last month.
As Sanba battered South Korea's southwest coastal areas, authorities canceled hundreds of air and sea services, Yonhap News reported. Prior to the storm's arrival, tens of thousands had been evacuated.
Sanba, with wind speeds of up to 93 miles per hour and unleashing heavy rains, was moving northeastward at 21 miles per hour, the Korean Meteorological Administration said.
The storm was expected to change direction toward the East Sea after crossing South Korea's mainland, the report said.
The Jeju Island, which was the landing spot of Typhoon Bolaven, was again the main target of Sanba's fury that included rains of more than 3 inches per hour. Already Mount Halla on the island has received about 23 inches of rain.
Dozens of residents have suffered flood damage, and more than 10,000 households were left without electricity, the National Emergency Management Agency said.
Nationwide, at least 208 flights and 130 ferry services had been suspended as of Monday morning as typhoon advisories remained in effect in most parts of the country, including Seoul where heavy rains were in forecast.
Yonhap said major dams in the country discharged water to control their water levels ahead of the storm.
A spokesman for South Korean President Lee Myung-bak had ordered the military and other agencies to be prepared for any emergency relief and recovery efforts.