A burst of wild weather with hail and thousands of lightning strikes have blasted parts of the North Island's west coast as a storm moves over the country.

The unsettled forecast is set to continue into the start of the weekend, before a cool southerly change brings a return of winter, and a blast of snow to the South Island.

Residents in Waiuku, just south of Auckland, experienced a heavy burst of hail between 3pm and 4pm on Friday, blanketing fields and orchards.

Baljinder Randhawa Sonu told the Herald they were at a friend's kiwifruit farm at the time, and the heaviness of the hail brought down metres of fruit covers.

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MetService forecaster Sonja Farmer said the hail was part of a "very active storm system" moving over the North Island on Friday.

The unstable west to northwest flow covered much of the island through the day, with periods of rain, showers and thunderstorms.

As of 6pm, Farmer said there had been more than 4000 lightning strikes.

Hail struck parts of Waiuku on Friday afternoon. Photo / Baljinder Randhawa Sonu
Hail struck parts of Waiuku on Friday afternoon. Photo / Baljinder Randhawa Sonu

The risk of thunderstorms continued into the early evening about northern and western areas from Northland to Taranaki.

These would be accompanied by brief heavy rain, hail, and squally wind gusts of 80-90km/h in a few places.

There was also a moderate risk of a few thunderstorms about Bay of Plenty tonight with brief heavy rain and hail, and a low risk covering many other North Island areas this evening.

Parts of the South Island also experienced some thunderstorms through the day.

Hail in Waiuku on Friday afternoon. Photo / Baljinder Randhawa Sonu
Hail in Waiuku on Friday afternoon. Photo / Baljinder Randhawa Sonu

An unstable westerly flow would cover the North Island early on Saturday, however, a cool southerly wind change in southern and central North Island areas would arrive during the morning.

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This would reach Auckland by about midday. Showers, possibly thundery, were forecast in the city to clear in the afternoon and before turning fine with a high of 15C.

There was a moderate risk of thunderstorms about western North Island areas from Taranaki to southern Northland during the morning, and a lower risk of thunderstorms spreading further east.

There was also a risk of a few thunderstorms associated with a southerly wind surge about coastal Marlborough, Wellington and Wairarapa before dawn, and about coastal Hawke's Bay later in the morning.

Hail weighing down kiwifruit nets in Waiuku on Friday afternoon. Photo / Baljinder Randhawa Sonu
Hail weighing down kiwifruit nets in Waiuku on Friday afternoon. Photo / Baljinder Randhawa Sonu

Any thunderstorms that occur will be accompanied by brief heavy rain and small hail.

The cold southwesterly flow was forecast to arrive in the South Island overnight, with road snowfall warnings in place for Saturday morning about Lewis Pass (SH7), Porters Pass (SH73), Lindis Pass (SH8), the Crown Range Rd, and Milford Rd (SH94).