Rain is expected to ease from midday Thursday in Nelson, where there's been a torrential downpour as the dregs of Cyclone Donna met with a low trough over New Zealand.
Most parts of the North Island are preparing for heavy rain which is expected to hit on Thursday afternoon, potentially bringing slips and more flooding.
MetService has issued a severe weather warning for much of the lower and central North Island, forecasting Mount Taranaki and parts of the Bay of Plenty and Gisborne ranges to receive 150mm to 200mm of rain.
Lower lying parts of Bay of Plenty and across the central North Island's high country to the headwaters of the Whanganui River may receive 100mm to 140mm of rain.
MetService says the effects of the Donna's remnants were more uncertain as the weather system is expected to pass near to the North Island's east coast.
"A decaying low to the west of the country will get a last breath of life through an injection of moist tropical air from the remnants of Tropical Cyclone Donna, which is currently expected to pass east of the North Island this Friday," MetService posted on Facebook.
Donna will no longer be a cyclone when it gets to New Zealand, but is expected to bring heavy rain and gale-force winds.
Aucklanders should expect the heaviest rain on Thursday night, with northeast gusts up to 100km/h possible in exposed places, MetService says.
It comes after a very wet April, when New Zealand was hit by flooding, slips and power outages as the tail ends of Cyclone Debbie and Cyclone Cook swept through.