Flash floods hit homes as heavy rain battered northern Thailand.

Footage shows villagers panicking as a swollen river threatened to spill over a wall protecting their houses in Chiang Rai on Tuesday.

Authorities said persistent rain caused severe flooding in northern provinces on Tuesday.

Water levels reached up to two metres (6.5 feet) in some areas as locals evacuated their residences in Lampang. Several pets drowned while vehicles parked on the street were submerged after the Ngao River burst its banks.

The Northern Meteorological Centre reported that northern Thailand was being lashed by heavy rains due to the combination of a low-pressure cell covering Laos and northern Vietnam, and the strong southwesterly monsoon prevailing over the Andaman Sea and the Gulf of Thailand.

Thunderstorms were expected to affect 80 per cent of northern Thailand, with heavy to very heavy rain in some provinces, including Chiang Mai, the agency said.

Thailand and neighbouring countries in Southeast Asia are at the start of their annual monsoon rainy season which sees soaring temperatures followed by powerful rain storms. The rudimentary infrastructure often struggles with the deluge, leading to widespread flash floods.