Typhoon Kompasu has struck the South Korean capital, downing power lines and causing transport chaos.
At least three people were killed and dozens more injured in the storm - the strongest to hit Seoul in 15 years.
More than 120 flights were cancelled and power cuts hit major parts of the subway network.
Further south, Tropical Storm Lionrock made landfall in the Chinese province of Fujian, bringing strong winds and torrential rain.
Forecasters warned that the storm could trigger landslides, Xinhua news agency said.
In Yunnan province, in the south of the country, rescue work continued after Wednesday's rain triggered a landslide in Wama village.
Four people are known to have died and 44 are missing in the wake of the incident.
Twenty-three people have been rescued in the village, which lies between steep mountains and the Nujiang River.
Typhoon Kompasu made landfall in South Korea early on Thursday at Ganghwa Island, before passing to the north-east of Seoul.
One man was killed after being hit by a flying roof tile and another died after a tree branch fell and hit him.
A man in his 70s was electrocuted, the National Emergency Management Agency said.
Utility poles and trees were knocked down in the capital and hospitals were full of people injured after being hit by flying glass, Yonhap news agency said.
The typhoon is now heading north towards the Sea of Japan (East Sea), meteorologists say.
On Wednesday state media in North Korea broadcast a typhoon warning, telling people to prepare for heavy rain.
North Korea has already been hit hard by floods during 2010.