Severe thunderstorms are possible for Auckland and Waikato on Thursday, with Metservice reporting downpours could cause flooding and slips.
A Severe Thunderstorm Watch was issued on Thursday morning for between 3pm and 10pm for the two North Island regions.
"Thunderstorms are expected to develop over the Auckland region this afternoon, and spread southwards into northern and western Waikato towards evening," Metservice says.
"These thunderstorms will be accompanied by localised heavy rain and small hail. There is also a low risk of a small tornado or funnel cloud."
The forecaster says "a few of these thunderstorms could be severe" and produce localised downpours of 25-40mm/hr.
"Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.
"Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain."
There are a number of other warnings and watches in place for parts of the country, including a Heavy Rain Warning for Bay of Plenty east of Opotiki and Gisborne north of Ruatoria, as well as a Strong Wind Warning for areas of Taranaki.
It comes as Weatherwatch says a large low pressure system will move over northern New Zealand tracking down across Northland and Auckland in the afternoon. This will produce "widespread rain and gusty winds" for the North Island
"In particular, heavy rain adding up to 100mm is expected in the Hawke’s Bay region during next 36 hours, a risk of localised flooding possible," Weatherwatch said. "Gisborne and Bay of Plenty region are also forecast to have 50 mm or more rain on Thursday."
Gusts in excess of 70km/h can be expected on coastal areas of the Cook Strait on Thursday afternoon into Friday morning.
A high pressure system will dominate the South Island from Friday "bringing cold nights". Temperatures are forecast to be colder than normal in eastern areas for the next two days.
"Overnight temps are quite colder and near or below freezing over Southland and Otago region on Thursday through Friday. The colder trends will move into the North Island, but turning warmer from Sunday.
"A next round of severe rain activity will kick in over the South Island from Sunday, heavy rain/snow and gusty winds likely in mainly western coastal areas as the westerly winds return."
