Heavy rain is likely to pound the lower Northeast, the East, the Central Plains, greater Bangkok and the South from Oct 7-9, the Meteorological Department warned on Tuesday.
The department said an active low-pressure cell over the central South China Sea is likely to turn into a depression on Tuesday. It is expected to make landfall in southern Vietnam on Wednesday before moving westwards to the upper Gulf of Thailand.
Rain in the South is expected to be heavy to very heavy, exacerbated by the intensifying southwest monsoon across the Andaman Sea, the South and the Gulf of Thailand.
Waves in the Andaman Sea and the upper Gulf of Thailand are expected to be 2-4 metres high in places -- and more than 4 metres high during thundershowers, the weather forecast said.
All ships should proceed with caution and stay ashore from Oct 7-10.