Weathermen forecast heavy rain nationwide throughout Thursday night, and then gradual improvement until next Wednesday.
Chomparee Chompurat, director-general from the Meteorological Department, said heavy rainfall has been stil being documented in provinces in the North, the Northeast, the Central Plains, the East and the South on Thurs.
It was due to a strong southwesterly monsoon over the Andaman Sea and the Gulf of Thailand as well as the monsoon trough, which stretched from the Northern to a low-pressure program in the Northeast.
Residents were warned to keep alert for hillside runoff in areas of consistent rain, she stated.
Small boats should stay ashore in the Gulf of mexico and the Andaman Sea on Thursday, because of waves that were 2-3 metres high.
From Friday to Sunday the monsoon would be weaker and the trough would move northwards in order to Myanmar, upper Laos and upper Vietnam, she said. Large rain would keep on only in some areas of the East and the western coast of the South. Waves might drop to 1-2 metres high.
From next Monday to Wednesday the monsoon over the Andaman Sea as well as the Gulf of Thailand would further drop strength and rainfall would become scarce. Waves would be 1-2 metres high.