Latest: Domestic flights were cancelled in South Korea Sunday as Typhoon Chan-hom brought strong winds and heavy rainfall to southwestern provinces.
The storm grounded 60 domestic flights linking Seoul with the southwestern coastal city of Yeosu and the southern resort island of Jeju, airport authorities said. International flights were not affected.
A strong wind alert has been issued along South Korea's southern and western coastal areas, which received up to 197 millimetres (7.7 inches) of rain as of 11:00 am (0200 GMT).
Weather authorities said the typhoon would be downgraded to a tropical storm when it reaches North Korea's Hwanghae province on Monday morning.
Typhoon Chan-hom swiped eastern China on Saturday, paralysing transport links and devastating farmland as authorities evacuated more than a million people, the Chinese government and state media said.
Five people in the Philippines were killed earlier in the week and more than 20 people injured in Japan on Friday.
Taiwan was also affected by the storm, closing its stock market and shutting schools and offices Friday as heavy rainfall and fierce winds battered the north.
A number of flights in and out of Japan's Okinawa island chain and northern Taiwan were cancelled.
The US government's Joint Typhoon Warning Center forecast that after hitting China, Chan-hom would head towards the Korean peninsula, bringing "gale-force" winds to the west coast of South Korea.