Christchurch was hit by a fierce wind storm last night which caused power outages, trees falling and car crashes.
Some Canterbury residents can expect to be without power for up to five days, thanks to the spring storm that's savaged parts of the South Island.
The front is on its way north, with severe weather warnings now in place for Marlborough, Nelson, Waitomo and Waikato.
Send your weather related stories, photos or video here.
Lines company Orion's Chief executive Rob Jamieson said power was out to 17,000 Orion customers this morning, down from 28,000 overnight when strong winds affected power lines across the network.
Most power cuts were due to trees or branches falling onto power lines.
Power had been restored to most of urban Christchurch, and affected areas were predominantly in the rural region west of the city, Mr Jamieson said.
Half of Orion's major rural substations were without power and teams were continuing to assess the extent of the damage, he said.
"Until we are able to bring the substations back on line, it is difficult to determine the extent of the damage throughout the rest of our rural network.
A tree breaks through a fence in the Christchurch suburb of St Albans. Photo / Dale Kershaw
"Access is proving very difficult and our crews are working as quickly as they safely can.
"As access will remain an issue for at least the remainder of today and its clear there is extensive damage, customers need to prepare for the possibility of extended power cuts,'' Mr Jamieson said.
"In some cases, power could be out for up to five days.''
MetService meteorologist Daniel Corbett said the weather front was a "dogs dinner, and it's not done yet".
"It's been a pretty nasty front, it's had some bark, it's had some bite and it's not done yet. It's moving its way north."
MetService has warned a severe weather watch is in place for Waitomo, Waikato, Marlborough and Nelson.
A burst of heavy rain in Waikato and Waitomo was expected tomorrow, senior forecaster Erick Brenstrum said.
"An active front should move slowly north over the South Island to lie across Cook Strait at midnight tonight.
"It should then cross the North Island on Thursday. This front is preceded by a very strong northwest flow and there are warnings for severe gales for many areas."
Northwest gales could reach severe gale force in Nelson and inland parts of Marlborough today, Mr Brenstrum said.
Over Westland, widespread severe gales were no longer expected, but a watch was in place for severe thunderstorms which may produce wind gusts exceeding 120km/h over localised areas.
"People in these areas are advised to stay up to date with the latest forecasts."
New World Temuka and New World Waimate were closed due to the power outage, a spokeswoman said. However, New World Temuka is now open and operational.
The front reached Wellington yesterday afternoon, with wind gusts reaching 120km/h.
An ancient elm cracked in fierce gales and hit a rented bungalow in Christchurch. Photo / APNZ
When an ancient elm cracked in fierce gales last night and crashed into her roof, terrified Shannon Swann leapt onto her flatmate's knee, thinking Christchurch had been hit by another massive earthquake.
Shaking with fear, Ms Swann and Kylie McFaul ventured outside into the howling wind holding hands.
They were staggered to find it was not a quake which caused the loud bang, but a huge branch of the more than 80-year-old tree that had come down on to their rented bungalow.
This morning they were waiting for news on what happens next, and counting their lucky stars.
"You're alive, that's the main thing," Dudley St neighbour James Bonell told 30-year-old Ms Swann.
The tree has broken tiles and guttering, but Ms Swan and Ms McFaul are unsure if there's any more significant damage.
A KiwiRail spokeswoman said rail lines were closed between Dunedin and Ward, south-east of Blenheim, as well as between Haast and Rolleston due to extremely high winds which brought trees down over the tracks overnight.
"We've also got a number of level crossings out of action but there's no trains running on them.
"We've had staff on-site since first light making repairs. We expect an update later this morning.''
In Wellington, a tree which fell over the tracks on the Wairarapa line this morning caused a 20 minute delay, but the service has since resumed, the spokeswoman said.
Motorists travelling between Canterbury and Otago have been cautioned.
Oamaru woman Lyn Warrington was with her daughter on Coast Rd when a gum tree crashed behind their car. "We're in shock ... It was halfway across the road," Ms Warrington said.
Severe gusts on Dunedin's northern motorway and in North Otago caused at least two trucks to overturn.
At Totara Estate, winds picked up and dumped a truck and trailer unit.
Oamaru Acting Sergeant Ewen Graham said the wind picked up the trailer first and then the truck, and threw them off the road.
The truck landed on the west side of the road, upright, while the trailer was tipped on its side.
The driver escaped uninjured.
"He was just shaken and got a hell of a fright," Mr Graham said.
A truck lies facing the opposite way it was heading on State Highway 1 north of Dunedin, after being blown over. Photo / ODT
A witness told Waikouaiti Constable Jon-Paul Tremain a truck was hit by a severe gust just south of Waitati, near Dunedin, and "lifted the passenger side of the cab up ... the wind was so strong it basically had taken the truck and thrown it across the road".
The wild weather has caused disruptions to air traffic, with flights to and from Christchurch and Wellington affected.
A Christchurch Airport spokeswoman said the airport was closed for a couple of hours overnight but reopened at 1.30am today. Flights were operating as normal this morning.
In the capital, the airport remains open this morning but some flights to and from Wellington Airport have been diverted or cancelled due to high winds.
An airport spokeswoman said passengers should check whether their flight has been affected, either on the airport or their airline's website.
Flights to and from Auckland Airport were unaffected, other than those disrupted due to the weather at other centres.
An Interislander ferry spokeswoman said one ferry was running an hour behind schedule and the second sailing had been cancelled.
"We're unsure as to whether that will be running for the rest of the day."
Bluebridge ferry spokeswoman Wendy Patton said there had been no delays or cancellations so far.
"Generally the northerly doesn't cause as much havoc as the southerly does for the ferries."
Ms Patton said they would be monitoring the situation and keeping an eye on updated weather forecasts.
Police southern communications Inspector Alan Weston said hundreds of extra 111 calls were received as a result of last night's storm, due to blown over trees and downed power lines.
"People just have to drive to the conditions and be aware that there is debris on the roads. They have to also be aware of the powerlines and telephone lines that could be down in different areas."
Fire crews attended this fire near Ashburton yesterday caused by downed powerlines.
Severe gales left a trail of fire and destruction in their wake as they headed north and away from the hard hit Canterbury area, said New Zealand Fire Service spokeswoman Karlum Lattimore.
Four helicopters had been dumping water on a fire in the Ashley Forest in North Canterbury this morning, she said.
Principal rural fire officer Allan Grigg said latest reports suggested the rain had helped and "the fire is no longer the raging monster it was''.
"We had one report last night of it appearing to have a five kilometre front. The helicopters were fighting the fire on two flanks while heavy machinery cleared fire breaks.
"We will bring in ground crews this afternoon when the wind drops."
Meanwhile, Kaikoura firefighters had been tackling a house fire while a rural crew was attacking a small fire in a plantation inland from the town.
In South Canterbury, crews were responding to a fire in a tree line in South Eyre Road.
Fire Service southern communications manager Chris Munro said the number of calls had dropped significantly and crews were now able to respond to the many reports of trees fallen onto power lines, houses and roads.
Between 2.30pm yesterday and 5.54am this morning there were more than 1800 weather-related emergency calls.
Christchurch area manager Dave Stackhouse said two firefighters were taken to hospital suffering from smoke inhalation after tackling a large fire in West Melton last night. They have since been discharged.
A fire at Sandy Knoll badly damaged a large implement shed and stables, however no animals were lost.
Cromwell resident Jade McLellan described how a huge gust of wind, which she thought was a tornado, picked up her father's 9m, two-tonne boat and flung it over the fence.
"We had a big gust of wind come through which picked up the neighbour's trampoline and spun that above fence level. Then we saw the boat flip up off its trailer and into the next door neighbour's yard."
The MetService has predicted 250-300 millimetres of rain will have fallen near the main divide by 5pm this evening.
Environment Canterbury has warned that such a large amount of rain and would be likely to result in significant flood flows into the Rakaia, Waimakariri, Hurunui and Waiau Rivers.
Anyone near the rivers should be aware of likely flood conditions throughout today.
Fishers and recreationalists have been asked to be very wary of rising water levels.
"We witnessed about a five hectare block of plantation destroyed in about five minutes - 90 per cent of it gone.
"(It was) just like dominoes."
The Ashburton-born farmer had never seen a worse storm hit the area.
"I've never seen the destruction as bad."
The following schools are closed after last night's storm due to damage and power outages:
• Burnham School • Cheviot area school • Clearview Primary School • Darfield High School • Darfield Primary School • Ellesmere College • Fernside School • Kaiapoi North School • Ohoka School • Rangiora High School • Rolleston School
