The Meteorological Department predicts heavy rains in the western parts of the North, the Central Plain and the South from April 20 to 26 due to southwesterly winds and low pressure areas.
The department said on Sunday that heavy rains were possible from Monday to Sunday because southwesterly winds would be more powerful in the Andaman Sea, the country and the Gulf of Thailand from Monday to Thursday.
The department warned people in the western parts of the North, the Central Plain and the South to be prepared for possible flash floods and run-off.
Waves in the Andaman Sea could be two to three metres high from Tuesday to Sunday. Boats should avoid the upper parts of the Andaman Sea and people should take precautions while going offshore in the Gulf of Thailand and the lower part of the Andaman Sea.