A southwestern monsoon over the Andaman Sea and the Gulf of Thailand, combined with a low-pressure area over upper Vietnam will continue to bring heavy rain to much of the North and eastern Northeast.
Residents who live in hilly areas should be alert to the possibility of flash floods. In low-lying areas, streams and rivers may overflow their banks, the department added.
The upper part of the Andaman Sea will experience moderate winds and waves of about two metres. The lower part of the Andaman Sea and the Gulf of Thailand will see waves of one to two metres. In both areas, waves will be higher during thunderstorms and vessel operators are advised to avoid thunderstorms.
Tropical storm "Khanun" is moving towards the southern coast of Japan and will make landfall on Tuesday or Wednesday. Travellers to Japan are advised to monitor weather conditions, the department said.