Low pressure over Myanmar will create downpours and possible flash floods in 19 provinces, the Meteorological Department warned on Sunday.
The weather agency said the area of low pressure following a storm over the Gulf of Martaban will bring heavy rain to 19 provinces in the northern, central and southern regions. Some areas could be assailed by surging runoff and flash floods, it added.
Most parts of Bangkok will see thunderstorms and rain through Tuesday, the department said.
Rain has hit many provinces since Saturday and slippery road conditions were thought to blame for at least two fatal road accidents, a van inferno in Kamphaeng Phet that killed nine Myanmar nationals and an overturned bus in Khon Kaen that left one person dead and 29 injured.
The Disaster Prevention and Mitigation Department has warned officials to prepare for flooding and other consequences of the severe weather.