New Zealand braces for Cyclone Gabrielle's full impact

The New Zealand government is considering a national state of emergency, with tens of thousands of homes already without power as Cyclone Gabrielle approaches.

The damaging storm, first identified in the Coral Sea last week, has progressed across the South Pacific to sit around 350km north of Auckland as of noon (1000 AEDT) on Monday.

Cyclone Gabrielle passed over the Australian territory of Norfolk Island on Saturday night as a category two storm with gusts of up to 155km/h.

As it continues to track south, NZ meteorological agency MetService reported gusts of 159km/h at Channel Island, near the Coromandel Peninsula, on Monday morning.

MetService has issued dozens of weather warnings, including several red alerts, saved for the most destructive weather.

Prime Minister Chris Hipkins urged Kiwis to avoid non-essential travel and bunker down.

"We're still expecting the worst is yet to come," Mr Hipkins said.

"We have to take seriously the red weather warnings when they're coming through. It's a cyclone. It is something that could have a significant effect."

MetService's red warnings effect the North Island regions of Auckland and Hauraki Gulf islands, Northland, the Coromandel, Tairawhiti and Taranaki.

Some Whangarei residents have been asked to evacuate their homes ahead of high tide around 2pm local time.

Whangarei, Northland's regional capital, is among the wettest places in the country, with the airport receiving 184mm of rain in the 24 hours to 9am on Monday, more than twice its average February rainfall.

Emergency management confirmed 58,000 people were without power due to damaging winds, most from Northland.

Auckland, the site of record rainfall and flooding a fortnight ago, remains on high alert.

New Zealand's biggest city received 245mm across a 24-hour period on January 27 and 28, producing widespread flooding and killing four men.

MetService expects another 150-250mm of rain in Auckland over the next three days, raising concern for more flooding and slips which could wipe out infrastructure and homes.

Emergency Management Minister Kieran McAnulty said the national state of emergency was being considered at meetings every four hours.

"We have not reached that point and we may not have to. This is an all of government response with all agencies ready to respond as needed," he said.

Only two national state of emergencies have been issued in New Zealand; for the 2011 Christchurch earthquake, and the COVID-19 pandemic.

Regional states of emergency have been declared in several regions.

Emergency services attended more than 220 wind-related callouts overnight.

"Roofs lifting off homes. Windows blown out. A couple of places where trees have fallen on houses. Lots of fallen trees on roads and bringing down powerlines," Fire and Emergency NZ spokesman Vaughan Mackereth said.

In Auckland, 115km/h gusts have been recorded on the harbour bridge, which has been closed to traffic for long spells.

Air New Zealand has cancelled all flights in and out of Auckland and a string of regional airports on Monday, while Auckland ferries and many inter-city buses have also been cancelled.

Schools have been asked to consider closing by the education department, and many people have been asked to work from home and delay non-essential travel.

Cyclone Gabrielle's effects are likely to be felt across New Zealand until Wednesday, with tracking maps suggesting the storm will continue south to the Coromandel before heading east over the Bay of Plenty and Tairawhiti.

The storm's huge size means Wellington, at the base of North Island, and towns across the South Island will be hit, with damaging winds expected on Tuesday.