The death toll from the floods has now risen to 12 and is mainly attributed to flash flooding which has washed away homes.
Four people died in Buriram, in eastern Thailand, as waters gushed through the streets, while the death toll in severely affected Nakhon Ratchasima has risen to four.
The central provinces of Rayong and Trat have both reported one casualty, while a further two people were killed in Lopburi.
Rescue teams have helped evacuate stranded people by boat, as homes and huge swathes of farmland have been deluged.
The area to the north-east of Bangkok is worst affected after twice the amount of rain compared to this time last year.
Residents in Nakhon Ratchasima, where 30 of 32 districts are already under water, have been told to evacuate or move to higher ground after a local reservoir burst its banks.
“We told people to leave their homes if the building has only one floor, but in two-storey houses they can move up to an upper level,” interior minister Chavarat Charnvirakul said.
He says the government will double the emergency fund available to provinces for flood relief.
Prime minister Abhisit Vejjajiva has visited affected areas and offered aid to people whose homes and farms have been flooded.
Mr Abhisit says Nakhon Ratchasima is suffering its worst flooding in 40 to 50 years.
Wet weather has also hit Cambodia and Vietnam where dozens of people have been killed.
© 2008 Australian Broadcasting Corporation