The weather bureau has issued flood alerts for 19 provinces in the East, lower Central Plains and the South as Phichit and Ayutthaya remain swamped.
The Department of Disaster Prevention and Mitigation said the Meteorological Department has warned of possible flash floods and water runoff in the provinces over the next six days.
They are Trat, Chanthaburi and Sa Kaeo in the East; Phetchaburi and Prachuap Khiri Khan in the lower Central Plains region; and Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala, Narathiwat, Ranong, Phangnga, Phuket, Trang, Krabi and Satun in the South.
The weather bureau said a storm has gained strength in the Gulf of Thailand and the South, bringing with it heavy rainfall and gusting winds.
The department said flood-fighting preparations began in earnest in many provinces. Officials were keeping a close watch on the amount of rainfall and the rising levels of waterways. Rapid-deployment teams, vehicles and equipment were ready to be launched in case of emergency as residents may need to be evacuated from their homes in the event of flash floods.
The crests of reservoirs and large ponds were being reinforced to prevent breaches while temporary shelters were being put up according to emergency relief plans drawn up by provincial disaster mitigation offices. Water pumps were being readied for use.
Local residents were urged to closely follow weather updates and comply with emergency procedures if evacuation becomes necessary, said department chief Chayapol Thitisak.
Meanwhile, heavy floods have persisted in Phichit where more than 18,000 people in low-lying areas remain affected by inundation in seven districts, including downtown Muang district.
Ratipas Meekhamhaeng, chief of the provincial disaster prevention and mitigation office, said three of the seven districts were particularly hard hit by floods. They are Pho Thale, Bung Na Rang and Pho Prathap Chang districts.
The floodwater has reached one metre in some areas although the average levels in the communities range from 30cm to 50cm. Water from flooded communities was being diverted slowly because small canals and waterways were still holding a lot of water.
However, the office expects the flood will subside and the situation will return to normal in the next two weeks.
In Ayutthaya, residents in Ban Rong and Ban Kwang of Ban Ban district have demanded the authorities speed up draining water from their farms which act as water-retention areas.
Kulthida Thonglor, 40, deputy head of the Ban Rong community, said 52 households in the community have been flooded by up to 2.5 metres of water for three months since the beginning of the flood season. Although the Chao Phraya and Noi rivers were receding, floodwater covering residents' farmland used by authorities to retain excess water has remained high.