Continuous monsoon rains have caused a river to overflow at the Thai-Myanmar border.

The downpour raised the river water level to four metres deep, prompting the closure of the Mae Sai border bridge in Chiang Rai province, Thailand on August 7.

The rain reportedly started early morning on Sunday and continued until Monday.

Houses, restaurants, and shops in low-lying areas were affected by the flood, while parents were forced to carry children on their backs after the district's kindergarten school entrance was submerged under two feet of rainwater.

Authorities said the Mae Sai river level is expected to increase as the rain continues. They have already ordered officers to stay alert and find ways to prevent water from flooding into economic areas.

Thailand and other countries in Southeast Asia such as Malaysia, Indonesia, Myanmar and the Philippines are in the middle of their tropical monsoon rainy season, which lasts until October or November.

Soaring temperatures reaching 35 degrees Celsius are often followed by powerful tropical storms with thunder, lightning, rain and flash floods.