Funnel cloud sighted as gumball-sized hail pummels South Canterbury

A severe thunderstorm warning has been issued this afternoon by MetService, with gumball-sized hail falling in South Canterbury and a funnel cloud sighted.

MetService said a severe storm was detected about 12.15pm in the area of Ashburton and Timaru.

Timaru's main highway during a hailstorm. Source: Supplied / Sarah McNicholl

A severe thunderstorm watch remains in effect for Christchurch, the Canterbury Plains and high Country, as well as North and Central Otago.

A very large hailstone which fell at Saint Andrews near Timaru. Source: Nikyta Wisniewski

Timaru and Oamaru locals provided photos showing extremely large hailstones, with several also sighting a funnel cloud forming near Oamaru.

Two very large hailstones which fell in Timaru. Source: Elyse Ackroyd

Brad Dennison of Timaru said the hail was so large that it punctured holes all over the clear roofing at his workplace.

"It hit about bang on 12. The first few stones came straight through the roof," said Mr Dennison. 

"We're up on the roof covering up the holes and clearing the gutters before another one comes through."

Holes in clear roofing at a premises in Timaru after a severe hailstorm on November 20. Source: Brand Dennison

He said from where he is, he can see people on roofs all around. 

"The neighbours are all rallying together."

Canterbury Police tweeted that people should stay inside, and that if they were driving at the time a storm hit, they should put their phone away.

Hailstones - looking more like a coat of snow - blanket a yard in Timaru after a severe hailstorm on November 20. Source: Brad Dennison