The Thai Meteorological Department has predicted heavy rainfall in the North and the Northeast until Friday and warns of run-off, flash floods and landslides in several provinces.
The department said the weather conditions were possible because a monsoon trough was above the North and the upper Northeast, and the southwestern monsoon was strong over the Andaman Sea, Thailand and the Gulf of Thailand.
Officials warned of flash floods and run-off especially on slopes near waterways and low-lying areas. They recommended travellers avoid flood-prone roads during the period.
Flash floods, run-off and landslides were possible in Chiang Mai, Chiang Rai, Lampang, Nan, Phayao and Phrae.
Flash floods and run-off had already started and were critical in Nan where rainwater measured more than 340 millimetres. Flash floods struck communities and farmland in Bo Klue, Mae Charim, Muang, Pua, Tha Wang Pha and Wiang Sa districts of Nan, officials said.