At least 145 people have died after torrential floods inundated southern Thailand, officials announced as waters began to recede, exposing massive damage across the region.

The hardest hit area is Songkhla province, where the bulk of the fatalities occurred, and the city of Hat Yai has emerged as the epicentre of the crisis.

Hat Yai and surrounding districts suffered unprecedented rainfall — including a record-setting 335 millimetres in a single day — overwhelming rivers, canals and drainage systems.

Over a three-day period, rainfall totals exceeded 630 mm, flooding low-lying parts of the city, submerging streets, homes and vehicles, and leaving many residents stranded.

Authorities say more than 3.6 million people and over 1.2 million households across twelve provinces have been affected by the floods.

Entire neighbourhoods remain under water or buried under mud, while roads, bridges, power lines and essential infrastructure lie in ruins.

Evacuation efforts have relocated more than 16,000 people to temporary shelters; military helicopters and drones have been deployed to deliver food, clean water and medical aid.

Government teams are working to restore basic services and clear debris, but official warnings remain in force as residual flooding and further rainfall continue to pose risks.

Local officials have described the event as the worst flooding in decades.

As recovery efforts get underway, the scale of the destruction and human toll has triggered urgent calls for reassessing flood-management and disaster-response systems across southern Thailand.