This is the moment a hailstorm pummeled a school in northern Thailand.

Video shows hailstones falling amid a downpour at the Ban Lai Thung Hill Area Community Learning Center in Chiang Mai province on April 9.

A school teacher, Wipawadee Wongpia, said: 'It was raining for around 30 minutes when I heard the raindrops growing louder. I looked outside and saw hailstones pouring down. There was more hail this time than usual.'

The Thai Meteorological Department in an April 9 forecast said that northern Thailand, including Chiang Mai, would experience isolated thunderstorms with gusty winds and hail.

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