Plenty of sunshine is forecast across the country heading into the weekend but it comes at a cold, frosty cost.

Fine weather is predicted for Friday and Saturday along with freezing overnight temperatures.

"Temperatures are likely to be at their coldest overnight from Friday into Saturday, forecast to widely drop below freezing across both the North and South Island," MetService said.

However, a ridge of high pressure covering the country was expected to slowly move away east on Saturday, as a front approaches from the Tasman Sea.

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"This front is expected to pass over New Zealand during Sunday, bringing a period of rain to many places.

"Sunday sees the return of wetter weather, especially for the West Coast, on the plus side, with winds returning to the north we should find our overnight temperatures a few degrees warmer."

There was a moderate confidence that rainfall accumulations could reach warning criteria about Westland, Buller and northwest Nelson during this time, with a low confidence about Taranaki and the Tararua Range.

"A showery west to southwest flow follows this front on Monday, with westerly gales possible about the lower North Island."

There was a low risk of these westerlies reaching severe gale force about central Hawke's Bay, Wairarapa and the Tararua District from late Sunday to Monday.