BEIJING - Tropical storm Rumbia reached the South China Sea area at noon Sunday and is expected to move northwestward in the coming 24 hours, according to the National Marine Forecast Station (NMFS).

It is expected to turn into a strong tropical storm and land on some coastal areas in the western part of south China's Guangdong province and the northeastern part of Hainan province from Monday night to Tuesday daytime, it said.

Heavy and high seas have been witnessed in the central part of the South China Sea.

In related developments, the NMFS has issued a blue-warning on the tropical storm. Local governments and fishermen are told to be on their guard and not to go fishing offshore.

China has a four-color warning system for storm surge, with red being the most serious, followed by orange, yellow and blue.