This is the heartwarming moment a hero passerby helped a motorcycle rider who fell over during a rainstorm.

The man spotted the woman after she toppled over on a wet car park while being lashed with water during a tropical downpour in Bangkok, Thailand, on April 21.

They spent several minutes helping the woman to her feet while sheltering her with an umbrella.

Thailand and other countries in Southeast Asia such as Malaysia, Indonesia and the Philippines are approaching their annual monsoon rainy season, which lasts 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.