Weather as it happened: Lightning, thunder and 'golf ball-sized' hail hits South Island

Lightning, thunder and hail the size of golf balls put the wind up southern towns on Wednesday.

These live updates are now over.

4:53pm - WeatherWatch says most of the thunderstorms are starting to fall apart.

4:39pm - Police urge people in Canterbury to be safe on the roads, secure property and keep pets inside.

4:32pm - The storm in Christchurch has so far not brought the hail or tornados that ripped off roofs and air conditioning units from buildings earlier in the week.

4:10pm - Timaru man David Anderson told Newshub his Audi looks like it's been "sprayed with bullets".

4:09pm - Contractors are out clearing stormwater drains in Timaru after the hail stripped leaves from trees.

4:06pm - MetService says there's been 700 lightning strikes in the past two hours.

4:01pm - Newshub has also been told of major crop damage, and Fire and Emergency New Zealand has received more than 30 allouts between Timaru and Waimate.

3:59pm - In Ashburton, Wendy Robertson told Newshub the hail was bouncing around everywhere.

Robertson said the hail was driving down, leaving the town looking like it's snowed.

"It was just bouncing like you were in a golf driving range," she said. "It was just going in all directions."

3:56pm - The Timaru Library has been closed with the roof leaking, and there's guttering damage at the local art gallery.

There's also been a high number of reports of broken skylights and many cars damaged, the Timaru District Council says.

3:51pm - Mass lightning strikes are now hammering Christchurch.

3:45pm - NIWA has counted over 450 lightning strikes from Ashburton to Christchurch between 2-3pm.

3:30pm - Video supplied to Newshub shows Timaru's main street covered in massive hailstones.

The Timaru-based South Canterbury Museum said on Facebook the hailstones were "the size of golfballs". Another resident described it as "vicious".

Timaru District Council spokesman Stephen Doran told Newshub there had been damage to vehicles.

"Most of the damage we're seeing at the moment is to cars," he said. "There's lots of dented paintwork and roofs and bonets out there."

Doran said the council was assessing buildings to determine whether there had been any damage.

Fire and Emergency New Zealand crews were kept busy between south Canterbury's Timaru and Waimate with vehicle accidents and other weather-related issues.

12:45pm - The NZ Transport Agency says motorists are advised to take extra care in Canterbury on Wednesday.

"Be prepared to stop/pause your journey in a safe place for a while if you are able."

More thunderstorms are possible throughout Canterbury and Otago as the day moves on, MetService says.

"[The] main risk here is for the heavy rain and hail that comes with the thunderstorms."