Thailand's Meteorological Department on Tuesday issued a warning for people in the South to prepare for heavy rain that may lead to flash flood.

The department warned that residents in the southern Thailand should for widespread scattered rain with heavy falls in some areas and the danger of floods Tuesday and Wednesday.

People living near hillsides and waterways in southern province of Nakhon Si Thammarat, Phatthalung, Songkhla, Yala, Pattani and Narathiwat should prepare for possible flash floods and forest runoff, the department said.

There will also be strong wind-generated two to four-metre-high waves in the lower part of the Gulf of Thailand. All shipping should proceed with caution and small boats should stay ashore.