Monsoon storms have caused major flash flooding and landslides in parts of Tak and Mae Hong Son provinces in the North, cutting off land routes to many villages.
In tambon Mae Tan of Tak's Tha Song Yang district, heavy rains and strong winds have caused rock slips and landslides along a road linking the district with Mae Hong Son's Mae Sariang district, which temporarily blocked traffic Tuesday.
Since Monday, heavy rains have hit several parts of Mae Hong Son, bringing flash floods to tambon Mae Suad of Sop Moei district in the province.
Dozens of houses were damaged in the floods which also submerged several roads, cutting off access to many villages. Extensive damage to crops has also been reported, local authorities said.
Prachit Muangjaima, chief of Mae Ngao National Park, located in Sop Moei district of Mae Hong Son province, said the water level of the Mae Ngao River which runs through the park has risen over the last three days.
Mr Prachit said the river burst its banks Tuesday, and water inundated a road in the park and surrounding areas. The road was submerged under about 1.5 metres of water, cutting off traffic between the district and the national park.
The 36th Ranger Regiment, on duty in Sop Moei district of Mae Hong Son, sent flat-bottomed boats and troops to rescue people who were trapped in their flooded villages on Tuesday.
As well as the two northern provinces, rain has continued to fall in parts of Nakhon Phanom province for almost two weeks, raising the water level of the Mekong River to eight metres Tuesday.
Officials from the Nakhon Phanom Provincial Disaster Prevention and Mitigation department issued an alert warning residents living along the Mekong River to brace for possible floods from the river. They also warned people living near mountains to brace for flash floods and forest run-off.
Meanwhile, the Meteorological Department issued a warning, saying people in at-risk areas of the North and the upper Northeast should beware of accumulated rain and heavy rain that fell from Monday until yesterday.