Typhoon Noul made landfall in southern China's Guangdong province early Sunday, bringing heavy rain and strong winds and disrupting air and rail services in neighbouring Hong Kong.
China's National Meteorological Centre (NMC) issued a red alert, the highest level in the country's four-tier typhoon warning system, as the storm approached the coast.
Late Saturday night, the centre of the typhoon was about 100 km southeast of Huidong County in Huizhou City, packing maximum sustained winds of Force 14. The NMC said the storm was moving northwest at about 20 kmph and was expected to strengthen before making landfall.
After moving inland, Typhoon Noul is forecast to shift to a north-northwestward path and gradually weaken.
China's State Flood Control and Drought Relief Headquarters raised Guangdong's emergency response for floods and typhoons to Level III and activated a Level IV flood emergency response in Jiangxi and Hunan provinces.
The storm is expected to affect parts of Fujian, Jiangxi, Henan, Hubei, Hunan, Guangdong and Guangxi.
In Hong Kong, authorities raised the storm warning to Typhoon Signal No. 9 after the system passed within 80 km of the city. More than 410 flights and 150 high-speed train services were cancelled, while 28 temporary shelters were opened for residents.
The Hong Kong Observatory said the typhoon was weakening as it moved inland but warned of intense rainfall and the risk of flash floods. It said rainfall exceeding 30 mm per hour had already been recorded and was expected to continue.
Airport authorities said flight operations were expected to gradually resume after 6 pm on Sunday.
Typhoon Noul, whose name means "the glow of sunrise or sunset" in Korean, is the 12th typhoon to form in the Pacific this year and the third to strike China this month.
Authorities said more than 340,000 people were evacuated from Guangdong province ahead of the storm's landfall.