The Meteorological Department forecast is for very heavy rain in the North and the upper Northeast, with possible flooding in both regions and in the Central Plains and the East this week.
The department said on Sunday heavy rain was likely because a rather strong southwestern monsoon now covers the Andaman Sea, Thailand and the Gulf of Thailand. From Monday to Saturday the monsoon trough would stretch past Myanmar, the upper North and upper Laos and touch a low-pressure area in Vietnam.
Accumulative and heavy rain could cause flash floods, runoff and overflows in the western part of the North, the Central Plains and the East. It recommended small boats in the upper Andaman Sea be kept ashore until Friday as waves could be two to three metres high.