Thousands of homes are without power, flights have been cancelled and Auckland's Harbour Bridge is closed as the effects of Cyclone Gabrielle are felt across the top of the country.
Electricity lines company Vector said by 7pm about 15,000 Auckland customers were without power, on top of almost 8000 cut off in Northland.
"This number will change constantly as we restore homes and businesses but, with the weather due to worsen, we expect further outages overnight and tomorrow."
People in Coromandel and Gisborne in vulnerable areas are starting to evacuate, with worsening conditions expected tonight.
Coromandel Civil Defence controller Garry Towler says six evacuation centres will be open 24-7 while another 12 to 15 community-led centres are on standby to open if required.
An emergency alert text was sent to all people on the peninsula this afternoon.
Towler says most people appear to be heeding the warning, as traffic leaving the region is heavy. He's advising people to go to family or friends.
Earlier, Northland declared a precautionary state of emergency for an initial period of seven days, while Waka Kotahi confirmed all lanes on the Auckland Harbour Bridge were closed due to strong winds at 3.40pm, and has yet to reopen.
Speaking at today's official update, MetService meteorologist Georgina Griffiths said even with significant wind gusts in Northland already being reported, the weather today was just the start.
"This is the entree. This is not the impact day."
She said rainfall on Monday would be "significant" - up to 40mm in just one hour possible.
She said Aucklanders should see a pause in the wild weather late on Monday night, before severe southwest gales on Tuesday across the whole city.
She said they had not seen pressure this low in 40 years.
"This is a serious event for New Zealand."
The storm has caused damage to properties in the Far North as wind gusts of up to 140kmh have been recorded in exposed places.
A gust of 140kmh was recorded at Cape Reinga this morning. People had been warned to expect gusts of 120-130kmh or "possibly more" in exposed places.
Northland police reported flooding has started to impact State Highway 1 over the Brynderwyn Hills.
They also stated trees were down across roads around the region, including SH10 in Kāeo, SH14 in Maunu, and across Ngunguru Rd in Whangārei.
Prime Minister Chris Hipkins says central and local government had been working closely together on the cyclone response and is urging people to take the situation seriously.
Air New Zealand has cancelled several flights and services, including multiple long-haul international departures and all domestic services through the city tomorrow.
Air New Zealand Chief Operational Integrity and Safety Officer Captain David Morgan says to keep customers, staff and aircraft safe, the airline has made additional cancellations.
"We’ve cancelled five long-haul international arrivals into Auckland tomorrow as well departures. New York, Los Angeles, San Francisco and Singapore arrivals are operating as normal but may be required to divert to another New Zealand port."
"All Tasman and Pacific Island flights tomorrow have also been cancelled."
"In addition, all flights to, from or through Auckland, Hamilton, Tauranga and Taupo are cancelled through till midday Tuesday. We’d like to thank customers for their continued understanding if their plans are impacted."
In Auckland the Harbour Bridge was closed to all traffic about 3.30pm on Sunday, and residents in Coromandel and flood-prone Auckland areas were earlier told to consider evacuating early and avoid non-essential travel.
"Gabrielle has lost its tropical characteristics, this doesn’t mean it is weaker," MetService said this morning.
"It will be a very intense system as it moves closer to our shores in the coming days. Widespread severe weather is forecast with the worst expected on Monday/Tuesday."
A red heavy rain warning has been issued for Coromandel, Gisborne north of Tolaga Bay, and Auckland, including Great Barrier Island and other islands in the Hauraki Gulf.
An orange rain warning is in place for Gisborne from Tolaga Bay southwards, Wairarapa including the Tararua District, Eastern Marlborough south of Blenheim, including Kaikoura Coast, Bay of Plenty west of Whakatane, and Hawke's Bay (from Monday to Tuesday).
Strong wind warnings are also in place - including a red one for Coromandel Peninsula, Northland and Auckland (including Great Barrier Island and other islands in the Hauraki Gulf) until Tuesday.
MetService meteorologist Lewis Ferris said some areas had already seen up to 10mm of rain in an hour.
Tairāwhiti and the Coromandel were set to be worst hit today with the most severe weather arriving at 3pm, Ferris said.
Civil Defence Northland said there had been no major flooding-related incidents overnight.
Earlier, winds 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.
Gabrielle has 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.
Auckland and Coromandel
Rain has been falling overnight in Northland, Auckland, Waikato and Bay of Plenty. The wettest part of the country around 7am was 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.
"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.
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.
East Coast
East Coast residents are bracing for another onslaught of forestry slash as Cyclone Gabrielle arrives just weeks after Cyclone Hale.
Deputy Civil Defence Officer Nori Parata said her community was still recovering after slash blocked waterways and damaged properties during the previous cyclone.
She said slash was a lingering concern for the community, and expects Cyclone Gabrielle will undo all of the progress the town has made so far to clean up.
"Our beach has just been cleaned up and the waterways affected by the previous cyclone have been mostly cleared. We're probably expecting we'll be back in the same position after this event."
Parata said the Tolaga Bay community was digging deep to find the resolve to make it through yet another severe weather crisis.
- additional reporting NZ Herald
