The North Island was lashed with large amounts of rain overnight and thunderstorms and heavy rain will continue in some areas today.
MetService duty forecaster Brian Mercer said many areas received "significant" rainfall overnight, including 11mm dumped in Hamilton over one hour from 9pm.
Kerikeri received 38mm over the past 24 hours, Warkworth 29mm, Whitianga 35.8mm, Hamilton 27.2mm, Stratford 69mm and Inglewood 49mm.
It had also been wet in Wellington. Trentham received 49.2mm, while Kaitoke and Temarua in the Hutt Valley got 130mm and 144.2mm respectively.
High winds tore out a transmission pole near Cambridge, Waikato, cutting frequency of the airwaves for several Mediaworks and NZME radio stations, including Hauraki and ZM. Mercer said it remains unclear if it was because of a tornado or strong winds.
Mercer said conditions will ease in most places today, but the central North Island could expect thunderstorms, including hail.
However, most of the North Island will get a break in the weather, apart from Eastern Bay of Plenty, Coromandel and Northland where showers will continue through to tonight.
The South Island had been relatively calm apart from a few showers on the West Coast and Fiordland, but they will become more widespread today.
Southland and Central Otago will eventually clear. Fine spells are expected in areas including Dunedin.
A new front will move over the South Island tomorrow bringing rain to the West Coast and Southland.
The Eastern Bay of Plenty, Hawke's Bay and Gisborne can still expect showers and heavier falls can be expected in the Central North Island.
As the front moves up the country the temperatures will also slightly cool and winds will pick up, except in Christchurch, which will get northwesterlies.
The northerlies will turn to southwesterlies overnight Thursday.
