Throw an extra blanket on the bed tonight - tomorrow morning will be one of the coldest of the year.

Auckland is expected to be 2C at dawn, and some pockets of the city could drop to zero or just below.

That is near-record cold for Auckland in June. According to Niwa, the city's temperature has never fallen lower than -1.5C in June - in 1967.

Frost is likely across both the North and South Islands, and could appear in unlikely places like Auckland's North Shore and possibly even Northland, Niwa said.

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Metservice forecaster Sarah Haddon said there were similar conditions overnight to the coldest day of the winter on Wednesday, when it was 0.5C at dusk in Auckland.

"Overnight tonight we do have lots of areas, especially in the North Island with clear skies and light winds as well.

"So you're gonna get those cold, frosty temperatures in the morning."

It will be a fine day in Auckland, getting up to 13C, before cloud arrives in the evening.

That means warmer nights. Temperatures are expected to rise to 11C overnight on Sunday.

The skies are even clearer in the central North Island, meaning Waikato, Taupo, Central Plateau, and the Bay of Plenty will also have very cold mornings.