A fire believed to have been started by powerlines downed in Christchurch's monster storm spread over two kilometres - threatening nearby homes and farms.

Southern fire communications shift manager Brent Dunn said the vegetation fire started at 2.40am and nearly covered an area of about two kilometres on Springston's Powells Road.

"It destroyed a farm shed and threatened two other properties but they were okay in the end.

"Twelve appliances attended, plus the command unit from Christchurch."

Fire appliances were called from Burnham, Dunsandel, Kirwee, Leeston, Lincoln, Rolleston and West Melton, and the fire was extinguished by 8am, Mr Dunn said.

Powells Road resident Faye Musson said the fire was heading towards her property and caused sparks to fly over her house.

"[The Fire Service] got there just in time. We were ready to evacuate.

"About five or six houses along the road were affected and three or four [properties' occupants] got out and we were the next ones to get out."

The fire was believed to have been caused by downed trees bringing down powerlines in the storm, Mrs Musson said.

"It just spread along dry grass and into the trees. It was just hopping roads, going along the grass, going along the ditches and then jumping the road into another lot of trees.

"It gives you a bit of a scare, we were all packed up and ready to go."

Christchurch lines company Orion said good progress was being made restoring power after cuts caused by strong winds.

By 10.30am power had been restored to 5000 of the 9800 Orion customers affected by overnight power cuts.

Most cuts were due to trees and branches falling onto lines in rural areas inland from Christchurch and 4800 homes and businesses were still without power.

Areas affected included Brookside, Ellesmere, Greendale, Halswell, Hororata, Lincoln, Motukarara, Northwood, Prebbleton and Springston.

"Our crews continue to make good progress. We're working as quickly as we can, while making sure we don't compromise the safety of our teams," Orion chief executive Rob Jamieson said.

"We're watching the weather closely, as more winds are forecast later today."

Kaikoura deputy chief fire officer Craig Guthrie said a large truck was blown over when the storm hit the east coat town.

The driver was "okay" and had moderate injuries, he said.

While the wind had calmed down, drivers were still advised to take care.

Power lines were down "all over the show" and multiple trees were blown over when the storm hit about 5.45am, Mr Guthrie said.

WeatherWatch.co.nz analyst Philip Duncan said the winds were caused by a deep low south of the country and a big high to the north.

"The squash zone is smack bang over the South Island and those norwesters [are] coming up over the Southern Alps."

Wind gusts across Christchurch would have ranged from 70 to 100 kilometres an hour, Mr Duncan said.

"The winds are around the damaging threshold to slightly below it.

"It's not at the high end but there's these micro-bursts that can come through the valleys that are much stronger."

The bad weather would be heading towards coastal Marlborough, Wairarapa and Wellington later this afternoon, but should ease by the evening before resurging again tomorrow, he said.

Winds around coastal Marlborough, Southland and the Catlins tomorrow morning could be stronger than what was seen in Christchurch today, Mr Duncan said.

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- APNZ