Eight districts in Songkhla have been declared flood disaster areas, affecting more than 12,100 families living in 42 tambons.
Thamrong Jaroenkul, the governor of Songkhla, yesterday said half the province was officially a flood disaster zone.
The eight out of 16 Songkhla districts affected are Hat Yai, Sadao, Rattaphum, Khuan Niang, Chana, Thepha, Na Thawi and Saba Yoi.
Continuous and heavy rainfall over the past four days caused water levels in basins alongside important provincial canals to rise, leading to a high risk of overflow, Mr Thamrong said.
In Hat Yai, floods have reached the outskirts of the municipality, leaving the city encircled. Water flowed into workplaces and homes in surrounding villages, with floods reported to be more than 50cm deep in tambon Kuan Lang.
Kuan Lang municipality workers had to move their cars and machinery to higher ground as water levels continued to rise. They also warned people in nearby tambons of the risks ahead.
In Chumphon, 13 Thai trawlermen survived yesterday after their fishing vessel, the Rung Rassami trawler, was grounded and washed ashore in tambon Pak Nam Chumphon.
In Pattani's Muang district, high sea levels put strain on inland rivers, which overflowed and flooded the city centre.
Floods on most of the city's roads halted business and nightlife. Water levels reached as high as 50cm, officials said.
Shopkeepers were caught off guard as waters rose rapidly, but most succeeded in moving their products off the ground and placing bricks and sand bags in front of their front doors.
Areas across from Pattani's provincial hall and the city pillar shrine were flooded, as well as the main police station, the fire station and Muang Pattani municipality. Several other landmarks including the province's main school were also inundated.
The Pattani provincial governor yesterday warned people in Muang district of flash floods and asked them to move their belongings to higher ground.
Meanwhile, Narathiwat mayor Tanawit Chaiyanupong has intensified flood preparations.
A refuge and food supply centre has been set up at a school in tambon Bang Nak of Narathiwat's Muang district, and a team of rescuers are on hand to help.
Water levels there reached 30-40cm over the last few days.
Narathiwat Municipality officials yesterday urged residents to remain vigilant until Saturday, since the Meteorological Department is warning of heavy rains throughout the period.
Rapid flows from the Banthat mountains in Trang province also flooded agricultural land and more than 100 houses in Trang's Na Yong and Muang districts. The Trang governor has declared both districts disaster zones.
Water levels there have ranged between 20-90cm in the last few days due to continuous rainfall and forest runoff.
More than 20 soldiers from Ratsadanupradit Mahitsarapharki military camp in Trang have been distributing fresh water to flood victims and stopping cars from entering flooded roads.
In Phatthalung, floods affected more than 5,000 families, with water levels exceeding one metre. More than 50,000 rai of agricultural lands and rubber plantations were flooded, while several roads in villages were damaged by inundation.
Many houses in Nakhon Si Thammarat were flooded due to heavy rain and high sea levels. While the floods have not reached the municipality yet, water levels in nearby villages have ranged between 30-50cm.
Residents of coastal areas are most at risk, since strong winds and waves caused damage to more than 1,000 houses along the shore. Schools were also affected in tambon Pak Nakhorn, where classes had to be relocated.