In Ubon Ratchathani province bordering Laos, flooding has inundated thousands of rai of ricefields for three days while three villages in Don Mot Daeng district are completely under floodwater.
Roads leading to the villages are covered with floodwater for more than two kilometres and bridges are damaged.
Provincial officials are considering to declare two more districts disaster zones after earlier announcing 17 districts as disaster zones.
Officials said so far more than 27,000 households in Ubon Ratchathani have been affected by the flooding.
Disaster Prevention and Mitigation authorities in Amnat Charoen province, meanwhile, provided assistance to flood victims.
More than 50 houses in the provincial seat have been damaged while many roads are under water as high as 50 centimetres, making them impassable for small vehicles.
About 50 houses in Yasothon province are affected by the severe flood after a canal overflowed in Pa Tio district.
Soldiers helped the affected villagers move valuable effects to higher ground.
A number of canals in Nakhon Phanom province bordering Laos have overflowed, and thousands of rai of ricefield is completely inundated. But fishermen are happy as they could catch more fish in the river.
The weather agency warned that heavy downpours would continue in the Northeast and also urged people in the eastern provinces of Chanthaburi and Trat bordering Cambodia to be prepared for flash floods.