Tropical Storm Matmo was moving into Cambodia from Vietnam on Thursday, and was expected to bring heavy rain to the central part of Thailand, where temperatures are also dropping.
Phuwiang Prakhammin, director-general of the Meteorological Department, said Matmo made landfall in Vietnam over Qui Nhon city on Thursday morning and would arrive in Cambodia later in the day .
That could cause heavy rain, with accompanying runoff dangers, in the lower Northeast, the East, the lower Central Plains and the upper South, he said.
These conditions were likely to prevail in the Northeast and the East on Thursday, and extend to the Central Plains, the East and the upper South on Friday and Saturday.
Mr Phuwiang said a powerful high pressure system was covering the North, the Northeast and the Central Plains and temperatures would drop by 3-5°C in the North and the Northeast and 1-3°C in the Central Plains and the East.
Small boats were warned to stay ashore in the Gulf of Thailand until Saturday due to the strong northeasterly monsoon.