Severe weather warnings are in place for most of the North Island, with Cyclone Gabrielle due to arrive in the region on Sunday.

Winds have cut power, brought down trees and blocked roads on Norfolk Island, halfway between New Zealand and Australia, but it appears to have been spared the worst.

It's been downgraded to a Category 2 system, but forecasters warn it could still bring destructive winds and heavy rain. One resident said most of the properties on the island are not built to withstand severe cyclones.

Orange-level strong wind warnings are in place across the upper North Island, from Northland through to Hawke's Bay.

Air New Zealand has cancelled several flights.

Auckland and Coromandel

Rain has been falling overnight in Northland, Auckland, Waikato and Bay of Plenty. The wettest part of the country currently is Waitakere, West Auckland.

The rain is forecast to get heavier, with severe gales also likely.

MetService says the amount of rain forecast for Coromandel Peninsula and northern Gisborne is expected to cause dangerous river conditions and significant flooding.

Coromandel is under a red-level heavy rain warning, with up to 400mm expected on the ranges, and up to 250mm elsewhere. Monday afternoon/evening is expected to be the peak, and "cause dangerous river conditions and significant flooding", as well as slips.

Auckland and Great Barrier Island are under an orange heavy rain warning, with up to 250mm north of Whangaparapa and 200m south.

"There remains some uncertainty associated with the exact track of Cyclone Gabrielle. Changes may be made in following updates, and this may be upgraded to a red warning."

Auckland Transport is urging travellers to be extremely cautious. Executive general manager of safety, Stacey van der Putten, says although the worst weather is expected from Monday, Auckland is already feeling the cyclone's impacts.

She warns the Harbour Bridge may face closures or restrictions on short notice, and travellers should keep an alternative route in mind.

Van der Putten is also encouraging Aucklanders to reconsider travelling on Monday and Tuesday.

The New Zealand Defence Force is expecting to be called out for evacuations.

Lieutenant Colonel Steve Fisher has been working with Auckland Emergency Management to prepare for evacuations around the North Island. He said roughly 100 Defence Force personnel are preparing for the cyclone response in Auckland, with more positioned outside the city.

"I think based on the last weather events we've seen, evacuations are likely. But the issue here is that the cyclone is largely unpredictable, so we need to be ready to move assets around the North Island based on where the greatest need is."

An Auckland firefighter was frustrated by the dire lack of staff as the region faced yet another major weather event.

Firefighters' union Auckland Secretary Martin Campbell said his station will have even fewer staff than they had during the floods two weeks ago, and the lack of firefighters will leave Aucklanders vulnerable.

"It's the worst-case scenario - we're here to protect the public, we're here to do a job. We are being prevented from being able to do that… it frustrates us immensely because we know the organisation can and should be being doing so much better."

Maritime New Zealand is warning boaties to stay out of the water when Cyclone Gabrielle hits the country.

Spokesperson Michael-Paul Abbott said heavy rain can cause flooding which hides potential risks, and kayakers and stand-up paddleboarders should not be in the water.

He says bulk carriers, container ships, passenger ferries should have plans in place for such a weather event.

Northland

Northland is under an orange heavy rain warning, with up to 250mm expected south of Kaeo, and 150mm elsewhere. Monday afternoon/evening will be the worst of it.

The region had winds over 130km/h at 6am Sunday, MetService said.

MetService said the orange warning could be upgraded to red as the cyclone arrives.

An iwi in the far north says it's prepared to support its community when Cyclone Gabrielle hits.

Chief executive of Te Runanganui o Te Aupouri, Mariameno Kapa-kingi, said their team has already done welfare checks for about 200 people in Te Kao ahead of the weather.

Kapa-kingi said they're ready to help with the clearing of downed trees, and any other needs of the community during the weather event.

A number of marae in Northland may be available as welfare centres when Cyclone Gabrielle hits the region.

A health organisation based near Kaitaia, Whakawhiti Ora Pai, said it has been talking to marae in the area. General manager Errol Murray said several marae are prepared to step up if needed, and they have been doing welfare checks on vulnerable communities ahead of the cyclone.

"We just make do. Our team's already doing some welfare checks… seeing if they're prepared and make sure they don't need a reason to go out. We're also preparing food, kai and water."