Prime Minister Prayut Chan-o-cha has ordered authorities to prepare measures to handle the heavy rain and flash floods that are forecast across the country from Aug 10-15.
The order comes on the back of a National Water Command Centre (NWCC) alert warning of a rising Mekong River until Tuesday.
Gen Prayut expressed concern about the expected heavy downpours across the country. He ordered officials to provide the latest weather updates to residents in flood-prone areas, deputy government spokeswoman Rachada Dhnadirek said on Wednesday.
According to the NWCC, the lower part of the Mekong River has been hit by days of rain, sending water surging in Bolikhamxay province in Laos.
Also, a low-pressure trough is covering northern Vietnam and southern China, which is expected to dump heavy rain in the North and the Northeast of Thailand from today until Tuesday.
"Gen Prayut has assigned state agencies in eight provinces along the Mekong River to be prepared for potential floods in Chiang Rai, Loei, Nong Khai, Bueng Kan, Nakhon Phanom, Mukdahan, Amnat Charoen and Ubon Ratchathani," Ms Rachada said.
Residents along the Mekong River are warned to closely monitor its water levels and prepare for possible flash floods, she added.
The Thai Meteorological Department warned residents in the North, the Northeast and the South to brace for heavy rainfall while 60% of Bangkok and its adjacent provinces will see thunderstorms in the afternoon and into the evening over the next several days.
Southwesterly winds will prevail across the Andaman Sea and the Gulf of Thailand. Waves of about 1-2 metres are expected in the Gulf of Thailand or over 2 metres in the Andaman Sea during storms, it said.
Meanwhile, roads recently closed by landslides and subsidence have reopened to traffic after local authorities installed prefabricated Bailey bridges.
On Monday, flash floods and landslides damaged stretches of road along Highway 1256 and Highway 1081 in Bo Kluea district of Nan.
Even though the Bailey bridges can help traffic, motorists are advised to drive carefully as the edges of mountainsides may be prone to landslides.
More than 100 residents from 27 households in flood-hit Bo Kluea Tai and Bo Kluea Nuea sub-districts have been evacuated to a shelter for their safety.