It warned that flash floods and overflowing rivers and streams are an acute danger, especially in low-lying areas, until mid-week.
The monsoon trough – which spans the North, the Northeast, the upper Central and the East regions – will continue delivering downpours to the Northeast, the East and the South’s west coast.
The downpours will end when the monsoon trough shifts to Myanmar, northern Laos and northern Vietnam on Wednesday and Thursday, the department forecast.
All ships in the lower Gulf of Thailand should avoid thunderstorms and small boats in the upper Andaman Sea should remain ashore until the monsoon trough shifts, the department advised.
It also said that tropical storm “Doksuri” will intensify as it moves from the northern Philippines and the upper South China Sea to the coast of southern China from Tuesday to Thursday, but it will have no direct effect on Thailand.