The alert level was upgraded to orange - the second highest - on Saturday for the approaching super typhoon Mujigae, China's National Meteorological Centre (NMC) said.
China has a four-tier colour-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue, Xinhua news agency reported.
Mujigae, the 22nd typhoon of the year, was in south China Sea this morning, and is expected to move northwest at a speed of 20-25 kms per hour with strengthening force, according to the National Meteorological Centre.
It is forecast to make a landfall on Sunday noon at the coastal area of the southern part of Leizhou peninsular of Hainan, with a speed of up to 151.2 km per hour at its centre.
The typhoon will bring gales to the coastal regions of Guangdong, Hainan and Guangxi in the coming two days. Most parts of Hainan and Guangdong will experience torrential rain.