This is the dramatic moment soldiers rescued residents stranded by floods in southern Thailand.

Footage shows troops wading through waist-deep waters to assist locals trapped in their homes in Hat Yai on November 27.

Authorities said those rescued included an elderly couple with kidney disease, and a woman with chronic heart disease and her 11-year-old son. They were taken to Songklanagarind Hospital in Kho Hong for treatment.

Following the evacuation, the helicopter team carried out an aerial survey of the surrounding flooded areas. They identified 20 more residents still in their homes.

As water levels appeared to be receding, the locals declined to be evacuated. The team instead delivered food and drinking water to them.

Songkhla Governor Ratthasart Chidchoo on Monday declared all 16 districts disaster zones and ordered the immediate evacuation of children, the elderly and the sick.

On Sunday, high-clearance trucks arrived to evacuate more than 400 tourists from flooded hotels across the city.

Soldiers, volunteers, and local government units have also been mobilised to hasten relief efforts, but they were hobbled by limited phone signal in the area.

The Disaster Prevention and Mitigation Department said that floods hit nine southern provinces, affecting some 1,128,284 households and 3,221,958 people.

Authorities said today that at least 100 people have been killed in the catastrophic floods, described by Prime Minister Anutin Charnvirakul as 'the worst flooding in 15 years'.

The Thai navy said it was preparing to deploy 14 boats and the aircraft carrier Chakri Naruebet to southern Thailand, with medical teams, supplies, and field kitchens able to supply 3,000 meals a day.

The navy said in a statement: 'The fleet is ready to deliver forces and carry out actions as the Royal Navy orders.'

The Southern Eastern Meteorological Centre said a strong monsoon trough was causing the heavy rainfall, which was expected to ease this week.

Thailand and neighbouring countries in Southeast Asia are in their annual monsoon rainy season which sees soaring temperatures followed by powerful rainstorms in the afternoon leading to widespread flash floods.