Almost nine Thai provinces have been struck by record floods, which have killed at least 33 people and prompted authorities to send military ships and helicopters to support relief efforts and evacuate critically ill patients.
As reported by the BBC, the city of Hat Yai, a business hub bordering Malaysia, recorded its heaviest rainfall in 300 years, 335 mm in a single day.
Scenes from the states show vehicles and houses submerged in rainwater, as residents await rescue on their rooftops.
Relentless rains have also ravaged neighbouring countries. In Vietnam, the death toll has risen to 98 in a week, while in Malaysia, more than 19,000 people have been forced from their homes.
In Indonesia, floods and landslides this week have claimed at least 19 lives.
More than 2 million people in Thailand have been affected by the floods, but just 13,000 have been moved to shelters.
The vast majority are cut off and unable to get help, according to Reuters news agency.
About 20 helicopters and 200 boats drafted into the Hat Yai rescue effort have had difficulty reaching stranded people, government spokesman Siripong Angkasakulkiat told reporters.
The Thai military, which has been put in charge of tackling the crisis, said it is preparing to dispatch an aircraft carrier and a flotilla of 14 boats loaded with relief supplies, along with field kitchens that are said to be able to deliver 3,000 meals a day.
Medical teams on board the aircraft carrier will convert it into a “floating hospital” if required, the navy said.
Boats, high-clearance trucks, and jet skis have also been deployed to evacuate residents, said the governor of Songkhla province, where Hat Yai is located.
In Malaysia, more than 19,000 people have been evacuated to safety, with 126 evacuation centres set up in the northern border areas.
For the unversed, heavy seasonal rain is a common sight around this time of year in Southeast Asia, but this year has seen exceptionally high levels of flooding in the region.