Flood-ravaged Auckland is forecast to receive further heavy rain in the coming days, authorities in New Zealand’s largest city say, as insurers count the costs of what looks likely to be the country’s most expensive weather event ever.

Four people lost their lives in flash floods and landslides that hit Auckland over the last three days amid record downpours. 

A state of emergency remains in place in Auckland. A state of emergency in the Waitomo region south of Auckland was lifted.

Flights in and out of Auckland Airport were still experiencing delays and cancellations, with thousands of passengers still stranded, including hundreds from overseas, flag carrier Air New Zealand said on Monday.

Beaches around the city of 1.6 million are closed and all Auckland schools will remain closed until February 7.

“There has been very significant damage across Auckland,” New Zealand Prime Minister Chris Hipkins told state-owned television station TVNZ on Monday.

“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 is forecasting further heavy rains to hit the already sodden city late on Tuesday.

“We have more adverse weather coming and we need to prepare for that,” Auckland Emergency Management duty controller Rachel Kelleher told a media conference.

Fire and Emergency services received 30 callouts overnight on Monday, including responding to a landslide when a carport slid down a hill.

The council has designated 69 houses as uninhabitable and has prevented people from entering them. 

A further 300 properties were deemed at risk, with access restricted to certain areas for short periods.

The north of New Zealand’s North Island is receiving more rain than normal due to the La Nina weather event.

The National Institute of Water and Atmospheric Research said Auckland had already recorded more than eight times its average January rainfall and 40 per cent of its annual average rainfall.

The cost of the clean-up is expected to top the $NZ97 million ($A89 million) bill for flooding on the West Coast in 2021 but will not be anywhere near as expensive as the estimated $NZ31 billion insured costs of two major earthquakes in Christchurch in 2010-11, Insurance Council of New Zealand spokesperson Christian Judge said.