Kai-Tak, the 13th tropical storm of the year, is approaching China's southern regions, the country's meteorological authority forecast Tuesday.

Kai-Tak, moving northwest at a speed of 15 to 20 km per hour, will graze or land on southern regions of Taiwan on Wednesday night or Thursday evening, before approaching coastal areas of Guangdong and Fujian provinces, the National Meteorological Center said.

Meteorologists suggested that authorities should call ships back to harbor, reinforce outdoor facilities, and evacuate workers on offshore oil platforms as the storm is moving fast toward the Chinese mainland.

Before its arrival, sweltering heat will continue to grip much of south China, with the mercury hitting as high as 39 degrees Celsius in some areas on Wednesday, according to the forecast.