A Christchurch weather expert says there were at least two separate tornadoes in the storm

A tornado ripped through the Garden City this afternoon, tearing off roof panels and blowing a parked truck across a yard.

Christchurch Weather Updates director, Russell Voice, says one tornado hit the central city in Sydenham and Linwood, and a water spout formed at sea.

He says thundery hailstorms and strong winds may be on the way, but more tornadoes are unlikely because it's starting to cool down.