Mountain run-offs inundated a village with muddy flood water as Thailand enters its rainy season.

Rescuers rushed to help residents in parts of Chiang Mai province after their homes were swamped from continuous heavy rain that streamed down from nearby mountains on May 18. Locals said the rain had been falling since May 17 evening, triggering an unprecedented flood in Ban Mae-O Nai village.

Rescue teams were deployed to evacuate the villagers, including some stranded elderly citizens.

The Office of Disaster Prevention and Mitigation said the flood has subsided, and they are continuing to send officers to help villagers in need. There were no initial reports of injuries or casualties.

Thailand's Meteorological Department said the country officially entered its rainy season on May 13. Bouts of rain showers are expected to occur until mid-October, with a dry spell possibly occurring from mid-June to mid-July due to the El Nino and La Niaa phenomena.

Thailand and other countries in Southeast Asia such as Malaysia, Indonesia and the Philippines are at the start of their tropical monsoon rainy season, which last until late November.

Soaring temperatures reaching 35 degrees Celsius are often followed by powerful tropical storms with thunder, lightning, rain and flash floods which cause rivers to flow faster and become dangerous.

Many of the under-developed nations struggle to cope with the heavy rain due to under-investment infrastructure.