Tropical Storm Kompasu will land in upper Vietnam on Wednesday or Thursday and bring heavy rain to the Northeast, the Meteorological Department warned on Tuesday.
On Tuesday the storm was in the upper part of the South China Sea and was expected to pass Hainan island and then land in upper Vietnam, and later weaken.
Heavy rain was expected in the Northeast of Thailand once the storm landed in Vietnam.
The department said the strong southwestern monsoon over the Andaman Sea, the South and the Gulf of Thailand, would also bring heavy rain to some parts of the lower North, the lower Northeast, the Central Plains, the East and the western coast of the South.
Small boats should stay ashore.