Bad weather will continue to dump heavy rain on the South at least until Wednesday, with its impact also felt in other parts of the country, including Bangkok.
Thai Meteorological Department chief Wanchai Sakudomchai warned residents in the southern, eastern and central regions to brace for downpours.
His warning came after storms hit the far South over the weekend, ravaging houses, uprooting trees and felling electricity poles in three villages, and causing blackouts in parts of Narathiwat's Rueso district.
A low pressure system, which brings rainfall, near Phuket Island in the Andaman Sea, remains intense and people in vulnerable areas could be at risk. Those areas are near mountains in Phuket, Nakhon Si Thammarat, Surat Thani, Krabi and Phangnga provinces, according to Mr Wanchai.
Tourist boats have been told to stay in port to avoid strong winds and waves more than two metres high.
In a related development, officials in Narathiwat on Monday inspected damage to three villages in tambon Batong where 300 people were affected by torrential rain on Sunday.
At least 61 houses were stripped of their roofs and many electricity poles were knocked down by fallen trees, according to the officials. The electricity pole damage caused a blackout for the entire night, with locals depending on light from oil lamps.
"We have to race against time to fix the houses as more rain is anticipated," Batong tambon administration organisation chief Nurumang Hayichewo said.
His rescue team has contacted the Provincial Electricity Authority to repair the electricity poles and also provide new roofing materials to residents.
Among them is Yisa Woli, 60, whose home was severely damaged after a coconut tree toppled onto her roof.
Fortunately, nobody in her house was hurt, she said.
The current weather conditions have not only triggered heavy rainfall in the southern region.
Southerly and southeasterly winds are now affecting the upper central and northern parts of Thailand are also dumping rain in some areas, yet to a lesser degree that in the South over the past few days.
The East and the Central Plains, including Bangkok and its vicinity, will likely be further soaked by rain, Mr Wanchai said.
The Meteorological Department expects the heavy downpours in the South and rainstorms in eastern areas and Bangkok and its vicinity to last for a full day.
However, Mr Wanchai said the situation would improve since the influence of the low pressure system is expected to weaken because it was moving Monday, westward to the Gulf of Martaban in Myanmar.
"This will make the weather return to normal on May 2 (Wednesday)," Mr Wanchai said.