As floodwaters started receding in the four southernmost provinces, the flooding expanded to four other provinces yesterday.
Residents in some areas were put on high alert for mudslides triggered by torrential rains which have pelted the South during the past three days.
People wade through run-off sweeping through Ban Phian village of tambon Thepharat in Sichon district of Nakhon Si Thammarat province yesterday. NUCHAREE RAKRUN
The floods have inundated tens of thousands of homes, forcing residents to seek shelter elsewhere and causing significant economic damage.
Nakhon Si Thammarat, Chumphon, Trang and Krabi were the latest four provinces to be hit by flash flooding and mountain runoff triggered by heavy downpours.
Thousands of residents in mudslide-prone areas, including Nakhon Si Thammarat's Nop Phi Tham district, have been evacuated to safe ground to prevent a repeat of last year's tragedy.
Mudslides hit the district in March 2011, killing several people.
But flooding in the southernmost provinces of Songkhla, Yala, Pattani, Narathiwat has eased and many affected areas have dried out. Officials said all would return to normal by today as long as the rains cease.
The continuing rain yesterday caused flash floods in three districts of Nakhon Si Thammarat, including Nop Phi Tham, Sichon, and Lan Saka.
Floodwaters cut off at least six bridges and roads in Nop Phi Tham district, leaving several villages isolated from the outside world, the Disaster Prevention and Mitigation Department reported yesterday.
Nop Phi Tham district chief Preecha Koomwong said tambon Krung Ching was the hardest hit area as floodwaters washed away temporary bridges built to replace the ones destroyed by last year's flash floods.
Mr Preecha said he feared there would be more flash floods and landslides if the rain continues this week.
In Sichon district, almost 200 families living in landslide-prone areas have been moved to evacuation centres after between 20 and 40cm of rain fell during the prior 24 hours.
Nakhon Si Thammarat governor Viroj Jiwarangsan said officials had been sent to disaster-hit areas to repair roads and bridges to enable the delivery of relief supplies.
Runoff from Banthad mountain also inundated some districts of Surat Thani, Trang and Phattalung provinces.
In 11 districts of Phatthalung, about 30,000 families' homes were flooded in tambon Kuan Saothong, where water reached two metres on Sunday night.
The waters began to recede yesterday afternoon.
Meanwhile, authorities have managed to contact the eight hikers who went missing during an excursion to Khao Lon mountain over the weekend. All of them were safe.
They said communication signals was down because of bad weather.
In Chumphon, Lang Suan Hospital in Lang Suan district was inundated yesterday afternoon. The water level rose rapidly, prompting medical staff to quickly move patients and medical equipment to higher floors.
In Thung Tako district, flash floods inundated a 200-metre section of Highway 41 linking Chumphon and Surat Thani yesterday, making it impassible to motorists, who had to use a bypass road instead.
The incident caused traffic congestion along the southern road which was already crowded with motorists returning home from the New Year holidays.
The Chum Phon-Lang Suan and Lang Suan-La Mae roads were also closed due to flooding.
Science and Technology Minister Plodprasop Suraswadi yesterday inspected Thung Wua Lan beach in Pathiu district which was damaged by high waves recently.
Mr Plodprasop said the ministry was planning to install a wave detection device to warn residents of high waves before they reach the shoreline.
He also ordered local authorities to take legal action against resort operators who have encroached on public beaches.
In other news, flooding in the southernmost provinces improved yesterday as the water quickly drained out to the sea.
Hat Yai's business district was spared from flooding, which affected only three communities in Hat Yai municipality.
Songkhla governor Grisada Boonrach said the Royal Irrigation Department has sped up the draining of water out of U-tapao canal.
He said the situation would return to normal shortly if there is no more rain, although authorities plan to keep a close watch for possible flooding today. On New Year's Eve, flash floods inundated the homes of more than 20,000 people in 12 districts of Songkhla, he said.
Public Health Minister Wittaya Buranasiri yesterday said three hospitals in Songkhla were slightly damaged by the floods. Three critical patients in flood-hit Sadao district were transferred to Hat Yai Hospital on Sunday.
In Pattani, floods receded in eight districts which were hit by flashfloods over the weekend.
However, residents were told to stay on alert for more flooding, especially those near Pattani and Sai Buri rivers.
Residents in six coastal districts were also warned of high waves and turbulent seas today and tomorrow.
In Narathiwat, floodwaters started receding in some parts of 10 affected districts.
Villagers living in landslide-prone areas were told to prepare for evacuation after five homes at the foot of mountains in Muang and Rueso were swept away by strong mountain runoff on Sunday, while 20 others were slightly damaged.
In Yala, floodwaters receded in Muang, Raman, Bannang Sata, Krong Pinang, and Yaha districts. The water level of the Pattani River, which breached its banks and inundated a number of communities on Sunday, was also receding yesterday.