MetService has issued multiple red severe thunderstorm warnings, with torrential rain, flash flooding and hail expected in parts of the North Island.
One of the new warnings issued is in effect for South Waikato, Waikato, Matamata Piako, Waipā, Taupō and Rotorua until 3.22pm.
A second red severe thunderstorm warning is in place for Waikato and Franklin until 3.45pm, MetService said.
Residents were urged by the National Emergency Management Agency to take shelter, preferably indoors away from windows.
If outdoors, people are advised to avoid sheltering under trees and to get back to land if they are on the water.
“Torrential rain can cause surface and/or flash flooding about streams, gullies and urban areas and make driving conditions extremely hazardous,” MetService said.
The forecaster warned that hail could cause damage to crops, orchards and vines.
Bay of Plenty east of Ōpōtiki and the ranges of Gisborne/Tairāwhiti north of Tokomaru Bay are under a heavy rain warning until 5pm.
MetService said a further 55-75mm of rain could fall with thunderstorms and localised downpours possible.
In the south, a severe thunderstorm watch for Dunedin, Clutha and Southland is in place from 2pm-7pm.
MetService expects thunderstorms in some northern parts of the North Island and west of the South Island as there is “plenty of juice in this broad low-pressure system”.
Meteorologist Paris Marshall said rising warm, moist air is partly to blame for the heavy showers and thunderstorms.
Auckland and Northland were among the areas “most at risk”, she said.
Auckland Emergency Management has advised people to look out for surface and/or flash flooding, as the ground is sodden after the heavy rain.
“Remember never, ever drive, walk or play in floodwaters in case of hidden danger, debris and polluted water.”
Coromandel Peninsula was under a heavy rain watch until 5am. Waikato, Waitomo, Taupō, Taranaki, Taumarunui and Tongariro National Park were under the same watch until 2am.
The ranges of Westland District and north of Mt Cook are under a heavy rain watch until 9pm.
There is some good news: Niwa forecasts a front will clear the country on Friday, bringing settled weather for the weekend.
“Expect strong northwesterlies and a burst of warmer temperatures,” Niwa said.
However, another front arrives late Sunday into Monday.
“Look for a windy and warm end to the weekend,” Niwa said.