China on Thursday upgraded its warning for ocean waves triggered by Typhoon Dianmu to a yellow alert, the third level on a four-colour warning system.

The National Marine Environmental Forecasting Centre (NMEFC) said waves reaching a height of six meters will hit northern and central parts of the South China Sea and the Beibu Gulf from tonight through tomorrow.

Meanwhile, waves up to 3.5 metres in height will hit the coast of Guangdong Province, Hainan Province, and Guangxi Zhuang Autonomous Region, state-run Xinhua news agency reported.

Typhoon Dianmu made landfall in the city of Leizhou, Guangdong in the afternoon whipping up ocean waves up to 5 meters in height in northern and central parts of the South China Sea and the Beibu Gulf.

NMEFC also issued a blue alert for storms.

China has a four-tier color-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.