Typhoon Prapiroon has struck southern China, bringing torrential rain and high winds, and killing at least 18 people.
The storm blew up from the Philippines, where it caused the deaths of six people, and skirted Hong Kong before hitting Guangdong Province.
Officials told around half a million people to leave homes in low-lying areas in Guangdong, Guangxi and Hainan, warning of floods and landslides.
More than 53,000 fishing vessels were recalled to harbour amid high seas and ferries connecting Hainan with the mainland were suspended.
Around 800 flights were cancelled in Hong Kong on Thursday, leaving thousands of passengers stranded.
The typhoon has now been downgraded to a tropical depression, but is moving further inland, where more bad weather is expected.