Wild weather set to hammer Auckland tomorrow night could cause power outages and see major costal roads closed by flooding.
Warnings were already in place for Auckland ahead of a king tide reaching its peak on Sunday evening, bringing potential lane or road closure for motorists.
Vector, Auckland's power provider, is also warning the heavy rain and severe easterly gales could cause power outages.
A low-pressure system was approaching New Zealand from the north, directing a strong and moist northeast flow over the North Island.
MetService said high tide in the Auckland coastal area on Sunday would be at 8.53am and 9.19pm, with the tide reaching heights of 3.5m and 3.7m.
Weather Watch said it was the combination of strong northeast winds and the king tide which could cause coastal flooding while heavy rain across the top of the North Island could also cause isolated flooding tomorrow and Monday.
Auckland Transport advised commuters to prepare for delays and closures around Tamaki Drive and Maraetai due to possible coastal inundation while also warning the Northern Motorway could become flooded between Esmonde and Onewa roads for those heading south.
Vector warned Aucklanders to put away garden furniture, trampolines and loose garden material which could be hazardous during the storm.
"Trees coming into contact with lines and cars colliding with power poles in the wet, are both possibilities when the worst of the weather reaches Auckland, particularly on the east coast and Waiheke Island," Vector's chief network officer Andre Botha.
Botha said extra crews were also rostered on to be on standby to deal with any outages.
On Sunday, there was a moderate chance rainfall accumulations would reach warning criteria in Northland, Auckland including Great Barrier Island, Coromandel Peninsula, Bay of Plenty, Gisborne and Nelson (especially northwest Nelson), according to MetService.
Weather Watch said there was likely to be between 30 and 50mm of rain in many northern areas tomorrow afternoon but the slow moving nature of the rain band coupled with the upper North Island hills and ranges meant there may be some isolated spots that could receive mre than double the forecast amounts.
The threat continued through to Monday, with the exception of Northland.
But the worst of the rain was set to hit the east coast, with a severe weather warning now in place for Gisborne, from Tolaga Bay northwards, and the ranges of Bay of Plenty east of Opotiki.
MetService said 70 to 100mm of rain could fall around the ranges from 3pm tomorrow until 6am Monday, with peak intensities of 10 to 15mm per hour.
In addition, on Sunday there was a moderate chance easterly gales would become severe about the northern half of the North Island, from Taranaki, Taihape and Gisborne northwards.
Meanwhile, there was a low chance of severe easterly gales for Whanganui, northwest Nelson and Buller on Sunday.
"On Monday, the flow should turn southwest as the low-pressure system moves east of New Zealand," MetService said.
More settled weather would come by Wednesday as a ridge of high-pressure moved onto the South Island from the west.