The devastating storm killed three people, left dozens injured and hundreds displaced when it hit the Hobsonville-Whenuapai area in West Auckland.
In Whenuapai and Hobsonville 520 homes have been damaged, with assessments carried out by Auckland Council building inspectors.
Twenty-two houses are seriously damaged.
Prime Minister John Key described the “utter devastation” he saw on a visit to affected areas, comparing it to damage inflicted during massive storms in the United States.
He also visited the construction site where Tom Stowers, Keith Langford and Brendon Johnson were killed.
“It could have been worse,” he told Fairfax NZ.
“There were over 200 men working onsite and another 150 at the primary school, including one guy working on the roof.
“So you get a sense of the potential size of the tragedy.”
As for the wider damage, he said:
“I can say I have never seen anything like this in New Zealand before.”
“It’s far more significant than a very bad storm where you have a few trees down.
“It’s something you would expect to see in mid-west America not in Hobsonville.”
A number of the damaged properties belong to the Defence Force.
“I understand 115 of those were Defence Force owned and 35 were rented out,” he said. “I would say a certain number of houses will be uninhabitable.
“Many were slated to be demolished so they weren’t in the best of condition anyway.”
The Auckland Council will find housing for those with no place to live, and it is also looking after lost animals at the West Auckland Animal Shelter.
The three men who died were crushed by a falling concrete slab at Hobsonville High School while sheltering in a truck.
Civil defence has estimated the damage will cost $11 million to repair.
Around 570 people were still without power, with some more remote area not expected to be reconnected until Sunday.
The tornado brought winds over more than 200kmh, the most damaging winds were “straight gusts” which came before and after the mini twister, the MetService said.
Meteorologist Dan Corbett said straight-line gusts of up to 110km caused considerable damage at Whenuapai.
“The mini tornado obviously does some serious damage but they also have the potential to kick out some serious winds as they release.”
Auckland mayor Len Brown said the response the the disaster had been outstanding.
“We have learnt a lot from Christchurch,” he told Radio New Zealand.
Brown said the residents had been hugely traumatised.
The storm had gone through the area several times: “It had gone around it like the tub of the washing machine.”