About 79,500 Auckland properties still have no power, and lines company Vector says some may not have the lights back on for three days.
Vector was aware of nearly 400 outages throughout Auckland, with "extensive" damage to its network from last night's ferocious storm.
At 8pm, Vector said 79,500 homes and businesses were affected by "ongoing power outages" after last night's storm lashed the region with hurricane-force winds. At its peak 182,000 properties were without power.
Vector has also issued a warning to the public about the danger of trying to cut trees away from nearby powerlines.
"We've had reports from some of our field staff that members of the public are taking it upon themselves to cut trees away from power poles and lines and/or moving downed lines from the roads or driveways themselves," the company said.
"We must stress to our customers – please, do not do this. Your safety and the safety of our field staff is our primary concern, and your actions could put yourself and others at risk. Our field staff will restore services as soon as it is possible and safe to do so. In the meantime, please always treat downed lines as live and stay well clear."
Auckland Council's contact centre has received approximately 1000 calls, mostly about downed trees and power outages.
Many bank ATMs and traffic lights are also not working.
A Vector spokeswoman said the priority was to restore "critical infrastructure" including hospitals and pump stations before outages that were affecting large groups of customers.
"For example if a feeder station goes down, that's 1000 or so people. We will prioritise that one before we get to the smaller individual jobs."
She said some more isolated customers may have their power restored sooner than expected, but "realistically that restoration time of two days, possibly three, still stands".
Last night's storm was "absolutely a big one", she said.
"The majority of the damage was from lines and power poles and trees coming down, but we also had feeders affected and [larger] infrastructure."
She was not aware of any damage to substations.
"The power outage in Auckland around Penrose substation in 2014 was big news and that was 70,000 customers, and took over 70 hours to restore.
"This storm overnight took out more than 100,000 customers in less than 24 hours."
Civil Defence Minister Kris Faafoi said he had spoken to Vector chief executive Simon Mackenzie.
"They've got all possible crews working to restore power. The basic message is if you don't have power and you've got family and friends to rely on and that you've got supplies to make sure you get through."
Vector had called for affected people to be patient as the work would take some time.
"It's a considerable amount of power outages to homes and a lot of work to get big trees off, it's not small branches in this instance, it's big trees that have come down," Faafoi said.
Mackenzie had indicated it could take two or three days to get to all the outages and crews in from outside Auckland to help out.
Facilities such as pump stations, rest homes and hospitals were being prioritised.
Faafoi said there had been a "fair bit" of warning to people that the weather would be bad.
"You can't predict exactly what's going to happen."
This morning Vector said there were 200-odd outages across the city but that had jumped to 400 by 11am.
"When our crews go to restore an outage they may find new damage which knocks out more people," the spokeswoman said. "Or they might have to respond to a call about lines down and switch off an area for safety."
The lines company has apologised after its app crashed during the night's fierce storm. Vector last night told people to report outages via their cellphones, but the app then went down, leaving people in the dark about how bad the outages were.
The app was reporting a "server error" for many people who tried to use it.
The call centre logged more than 10,000 phone calls about power cuts, lines down and other damage overnight.
Just before 11pm the company acknowledged people were having trouble with its app, and said it was "working to resolve this".
The company has now apologised for the issues customers had last night when trying to report power cuts and said crews are working as fast as they can to restore power.
Vector has not yet answered questions about what exactly went wrong with its app.
Network manager Minoru Fredricksens said the focus was on restoring power to those that need it most.
Staff worked through the night in hurricane-force wind and restored power to about 70,000 customers, Vector said.
Some of the power restoration work was impeded by fallen trees. Auckland emergency management director John Dragicevich said contractors had been working through the night to remove the trees so work could begin.
Weatherwatch forecaster Philip Duncan said he would be asking why forecasters did not predict the extent of the storm.
"We didn't see that there would be lots of trees down and half the city without power this morning. It was a notch higher than what we were expecting," he said.
The area of gales wasn't big but hit Auckland like a "wind tunnel", he said.
Further south, about 1000 central and lower North Island households are still without power after tornadoes, lightning strikes and strong winds knocked out power to 8200 houses.
Powerco said 8200 customers lost power early Tuesday as a result of the storm.
By late-afternoon today those still off-line as a result of storm damage had been reduced to 1000 and Powerco was hoping to make further gains before crews stopped for the night.
Powerco Network Operations Manager Phil Marsh said coastal Taranaki suffered the most damage and remained the main focus of restoration work.
"This is where most of our remaining outages are, particularly around Rahotu, and some people will be without power for another night," he said.
There were several days of work ahead of crews clearing trees from lines, replacing downed poles and realigning poles knocked out of position by the tornadoes.
He said about 4600 Tairua customers on Powerco's eastern network were without power for most of the day. Overnight winds toppled trees across the main feeder line to the Tairua substation.
What to do if you power's out
Auckland Emergency Management has issued instructions on what to do when the power goes down.
• Keep your fridge and freezer closed to keep food chilled.
• Throw away any frozen food that has been exposed to temperatures above 4C for two hours or more or that has an unusual odour, colour or texture. When in doubt, throw it out.
• If food in the freezer is colder than 4C and has ice crystals on it, you can refreeze it.
• Contact your doctor if you're concerned about medications having spoiled.
• Restock your emergency kit with fresh batteries, canned foods and other supplies.
• If your power is expected to be out for a day, conserve your hot water.
• More tips here on what to do with chilled and frozen food