Floods surged through a town and submerged the first floor of shops amid heavy rain in northern Thailand.

Footage shows the muddy deluge gushing through the perennially flooded Mae Sai District of Chiang Rai after the Sai River breached its banks this morning, July 28.

The first floor of shops at the Sai Lom Joy market were submerged by the floods, which overwhelmed sandbag barriers as the water level continued to rise at the Mae Sai Friendship Bridge.

The Department of Disaster Prevention and Mitigation has issued warnings to residents in four high-risk areas of the district, urging them to evacuate to higher ground.

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