The upper northern and western regions of the country are bracing for heavy rain this weekend, although tropical storm Son-Tinh is losing steam.
The Meteorological Department on Friday released a weather warning about the impact of the storm, as it began to move farther away from Thailand.
Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Phrae, Nan, Kamphaeng Phet and Tak were among the northern provinces hardest hit by heavy rains on Friday, it added.
Meteorologist Ekanong Kienthong said the situation would persist throughout the weekend.
"The upper part of the North and provinces along the western area through to the South will see rain and downpours in some areas on Saturday and Sunday," she said on the weather bureau's broadcast. Parts of the Northeast will feel the impact as well, she added.
Storm Son-Tinh entered the country from Vietnam on Thursday but lost strength along the way. Still, it caused flooding in some areas.
The Disaster Prevention and Mitigation Department said flooding was reported in at least 11 districts in five provinces: Trat, Phrae, Phetchabun, Phitsanulok and Prachuap Khiri Khan. Flooding was also reported in Kanchanaburi and Kalasin among others.
Provinces along the Mekong River were also hit by the storm on Thursday.
A section of Road 323 between Sangkhla Buri and Muang district of Kanchanaburi is flooded on Friday. (Photo by Piyarach Chongcharoen)
Chaiyaphol Thitisak, the Disaster Prevention and Mitigation Department chief, said officials had not lowered their guard against the prospect of more flooding.
After two days of downpours, Kanchanaburi governor Jirakiat Phumsawa on Friday declared Sangkhla Buri a disaster area after the entire district was inundated.
Flooding made Road 323 between Sangkhla Buri and Muang district impassable for small vehicles, causing traffic gridlock for several kilometres. The road is the only main link to the outside world for Sangkhla Buri.