Sukhothai and Phitsanulok have seen a resurgence of floodwater after a period of stabilisation as high-volume water flows wash in from upstream provinces.
Residents of tambon Yang Sai in Muang district of Sukhothai fled their homes after a 10-metre-long section of a road that acts as buffer against the Yom River broke due to river overflows.
The deluge immediately inundated the Moo 9 community along the road.
The floodwater rapidly rose to 2m leaving no time for residents to move their belongings to higher ground, said local resident Sanit Umthung.
He said at least five families with elderly members aged between 67 and 90 were stranded in their flooded homes.
Several other communities and roads in Muang district were reportedly under 2-3m of water yesterday morning as a result of the river overflowing, authorities said.
Parts of Sukhothai and neighbouring Phitsanulok where the river flows are seeing floodwater rising again. The river, which receives water from upstream northern provinces, has swelled and flooded homes and communities.
Piti Kaeo-salap, the Sukhothai provincial governor, said local administrative organisations had sent workers to build an embankment of sandbags to keep out water from the district's business centre.
In Kong Krailat district of Sukhothai, Suriya Srisil, 73, said his 30 rai of paddy fields were destroyed in a flood only a few days before a planned harvest.
Residents in Moo 11 of tambon Ban Kaeng in Si Satchanalai district, meanwhile, were struggling to plug cracks in a local reservoir blamed for flooding more than 500 rai of rice fields.
They were stacking up sandbags to close the cracks.
Mr Piti said the provincial office was working with local irrigation authorities to divert the northern run-off in another direction to lessen the water flowing into Sukhothai.
It was being "bypassed" through what is now a tributary of the Yom River and connected canals.
The diversion has led to a new problem as floodwater was worsening in Phrom Phiram district of neighbouring Phitsanulok.
Some 800 households in Chaiyaphum have been hit by the flooding, leaving damage estimated at over 100 million baht.