Twenty cars were damaged when a summer storm blew down tents in a carpark in Thailand.

Footage shows the gales whipping through the Racha Thewa Subdistrict Administrative Organisation office in Samut Prakan province on Tuesday afternoon April 25.

The howling winds caused the tents to billow and collapse, with staff scrambling to anchor them down. However, the harsh downpour forced them to seek shelter soon after.

The storm subsided after around 30 minutes, leaving 20 vehicles and 10 tents damaged.

Construction worker Yutthachak Kinnares who works nearby said: 'I saw the sky darken shortly before the strong wind blasted the area. The storm was so strong that the tents were nearly blown away.'

Songchai Nokkhamin, chairman of the Racha Thewa Subdistrict Administrative Organisation, said most of the damaged vehicles belonged to employees, who have already contacted their insurance companies for compensation.

The damaged tents will be replaced with new ones, he added.

The storm came as temperatures soared past 42 degrees Celsius last week during a heat wave across the Asia Pacific region.

Maximiliano Herrera, a climatologist and weather historian, described the scorching heat as the 'worst April heatwave in Asian history'.

In Thai capital Bangkok, residents were warned not to go outside amid 42 degrees Celsius temperatures causing power outages due to surging demand from air con units and fans running.

The country's national weather service said the heat index - what the temperature feels like when combined with humidity - hit a record 54C (129F).

The warm weather is now giving way to extreme tropical storms.

The Thai Meteorological Department warned that southerly and southeasterly winds prevailing over upper Thailand would strengthen between April 23 and 26.

Outbreaks of summer storms, accompanied by thunderstorms, gusty winds, hail, and lightning strikes, were expected to affect the northeastern and eastern parts of the country first, before spreading to other regions.