If you think it was freezing last night, you're probably right -but only if you live in certain parts of New Zealand.

The mercury dropped below zero at a number of places including Christchurch which recorded the country's lowest temperature of -1.9 degrees.

Mt Cook and Waiouru airports hit freezing earlier in the night - which the MetService said got gradually colder until sunrise.

The Mt Cook night camera captured a dramatic image of snow on the alps, the chilly conditions forming an ice halo around the moon.

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The MetService said ice halos could be seen on days "with wispy high clouds in the sky made of ice (cirrus clouds)".

"The 22° ice halo is just one phenomenon amongst a broad range of atmospheric optical phenomena that occur when sunlight is refracted and reflected through ice crystals, in clouds high up in the atmosphere," a spokesperson explained.

"Some of these show rainbow colours, as ice crystals can act like prisms, separating the different colours of light."

MetService expected some areas to experience frost, but said the country would warm up as the morning went on.

Fine weather is forecast today for Northland, Coromandel Peninsula, Bay of Plenty and Taupo.

Auckland, Waikato, Waitomo and Taumarunui will be mainly fine with cloud increasing this evening with isolated showers.

Remaining showers should be clearing this morning in Gisborne and Hawke's Bay which will become fine.

For Taranaki to Wellington, including Taihape and Wairarapa there will be cloudy periods and isolated showers from the afternoon.

It's going to be mainly fine in Nelson but a few showers about Golden Bay are expected this morning; and in Buller and Westland areas of cloud will develop with isolated showers.

People in Marlborough, Canterbury, North and Central Otago, and Dunedin can expect a fine day with morning frosts.

And for Clutha, Southland and Fiordland there will be cloudy periods with a few showers, mainly near the coast.

On Monday the North Island will have cloudy periods, isolated showers in Northland and Taranaki and in the South Island it will be mainly fine, with just a few showers about the south coast.