Four people died in flash floods and landslips that hit Auckland over the past three days amid record downpours.
A state of emergency remains in place in Auckland and Waitomo.
Flights in and out of Auckland Airport are still experiencing delays and cancellations, while beaches around the city are closed.
"There has been very significant damage across Auckland," Prime Minister Chris Hipkins said yesterday.
"Obviously, there were a number of homes damaged by flooding but also extensive earth movements."
About 350 people were in need of emergency accommodation, he said.
MetService forecast further heavy rains to hit late last night.
"We have more adverse weather coming and we need to prepare for that," Auckland emergency management duty controller Rachel Kelleher said.
Auckland Council has designated 40 houses as uninhabitable and has prevented people from entering them.
A further 151 properties were deemed at risk, with access restricted to certain areas for short periods.
The National Institute of Water and Atmospheric Research (Niwa) said Auckland had already recorded more than eight times its average January rainfall and 40% of its annual average rainfall.
The cost of the clean-up was expected to top the $97million bill for flooding on the West Coast in 2021 but would not be anywhere near as expensive as the estimated $31 billion insured costs of two major earthquakes in Christchurch in 2010-11, Insurance Council of New Zealand spokesman Christian Judge said.
Insurance Australia Group’s New Zealand divisions had received more than 5000 claims so far and Suncorp Group said it received about 3000 claims across the Vero and AA Insurance brands.
"The number of claims is expected to rise further over the coming days, with the event still unfolding and as customers identify damage to their property," IAG said in a statement.
Economists said the recovery and rebuild could add to inflationary pressures in New Zealand as vehicles and household goods needed to be replaced and there was an increase in construction work needed to repair or rebuild houses and infrastructure damaged by the flooding.
— Reuters
