Wrap up warm, today's going to be freezing

It's a day to wrap up warm, with many parts of the country struggling to reach temperatures in the double digits throughout the day.

The Desert Road is closed this morning to motorists because of snowfall and MetService meteorologist John Law said there could be more to come.

"For many places it's a really nice, cold, crisp winter's day," Mr Law said.

"It's looking like a really nice clear day, but very cold."

Watch: Cold snap has arrived

The southwesterly flow that had brought showers and brief thunderstorms to parts of Auckland and Northland would stick around today, Mr Law said.

"Showers will run through and some could be quite beefy," he said.

"There'll be a lot of wind and still the chance of hail."

Auckland is chasing a high of 13C today.

Bay of Plenty and the east coast of the North Island down to Wellington was in for clear skies and cool temperatures, Mr Law said.

"They got down to 3C last night, so it's certainly nice and cold there.

"As we move in more central to Rotorua they were just below freezing last night... and they're in for another cold night tonight."

SH1 Desert Rd & now SH47 closed due 2 #Ice & #Snow. USE SH4 via SH41 & SH49 http://t.co/70fhDfVfgL ^WS pic.twitter.com/NDHMeGsqWr

The Lifewise Big Sleep Out is on tonight in Auckland, with more than 100 people registered to sleep under the stars in Auckland and raise money to solve homelessness in Auckland.

Watch: Snow blankets the South

Mr Law warned those taking part would be in for an unsettled night.

"Be prepared for wet weather tonight," he said.

"There's a chance of some short, sharp showers."

Overnight the temperature is expected to get as low as 6C but with the high winds it will feel much colder, he said.

Snow showers are forecast for Southland and eastern parts of Otago down to 800 metres this afternoon.

Police later said that State Highway 47 (National Park) and State Highway 1 (Desert Road) were closed and there was no opening time scheduled for either at present.

Ice continued to pose a serious risk along SH4 Ohakune/Taumaranui and beyond.

"Motorists intending to travel along this road are advised to exercise extreme caution, drop travelling speeds considerably and remain aware of other traffic in the area. Best advice is to avoid this stretch of road unless absolutely necessary."

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