Heavy rain and strong winds are battering the North Island, flooding highways and damaging buildings.
A truck flipped on to its side north of Matamata this morning, with one person injured and the contents strewn across the road.
Emergency services responded to the crash in Tower Rd at Turangaomoana just before 7.15am.
Meanwhile, a large tree has fallen and blocked both lanes of a road near Hatfields Beach in Orewa.
The Kaeo River in the Far North, which is prone to flooding, has spilled onto State Highway 10 after heavy rainfall. A webcam of the river shows the water level is at almost 3.5 metres.
Schools are closed, thousands are without power and roads have been affected by flooding and slips across Northland.
Up to 2000 properties in Waitangi and Paihia lost power this morning as network provider Top Energy said the storm had damaged a key power line feeding the Haruru Substation in Northland.
Crews were working in "challenging conditions" and the company warned people to treat all power lines and electrical wiring as being live at all times.
At midday, two roads in Northland remained closed. A fallen tree has closed Upokorau Rd while a slip on Kohumaru Rd could take up to 24 hours to clear, says the Far North District Council.
However, the worst rainfall is still yet to come. MetService predicted peak rainfall intensities of 15 to 20mm per hour this afternoon and evening in Northland.
In Auckland, the wild weather led to a series of road accidents during the morning commute, including a car rolling on the Southern Motorway. Speed limits were reduced on the Harbour Bridge as a precaution.
Emergency services closed Halsey St in Wynyard Quarter after high winds appeared to damage panels on the outside of the Park Hyatt Hotel.
Winds of up to 120km/h were whipping up the Waitematā Harbour. Photographs showed a yacht sinking in Sulphur Beach in Northcote.
The new "rainmaker" weather event arrived overnight, bringing heavy rain and gale-force wind warnings for many of the North Island.
Heavy rain is falling across Auckland, Northland and other North Island areas this morning as the tropical low-pressure system moves in.
There are over 20 weather watches and warnings in place across the country and the worst of the weather is expected to hit the North Island from 10am to 2am tomorrow.
In the South Island, MetService have issued a number of road snowfall warnings including for Lewis Pass from 2pm to 9pm, Arthur's Pass 3pm to 2am tomorrow, Porter's Pass from 4pm to 1am, Lindis Pass from 8pm to 11pm tomorrow and the Crown Range Rd from 1am to 4pm tomorrow.
The wild weather will move south as the day progresses, with heavy rain warnings and watches in place for Northland, Auckland, Coromandel, Bay of Plenty, Mt Taranaki, Tasman and Marlborough.
MetService said streams and rivers could rise rapidly, surface flooding was possible, and driving could be hazardous, especially for high-sided vehicles.
There were also warnings of gale-force winds on the Hauraki Gulf this evening. Winds could reach 130km/h.
Just after 6am, Auckland Transport issued an alert that all Gulf Harbour ferry services will be replaced by bus and shuttle services today due to weather conditions.
The rest of the country is set for a wet few days, with rain and wind forecast for most areas.
The low and its associated fronts are expected to continue south until Thursday.
The 36-year-old died on December 19.