Wrap up warm for the next couple of days - temperatures are forecast to drop, but will make way for warmer and sunny conditions later in the week.
Auckland's temperature was 10C about 7am. A high of 14C is expected in the city, but an overnight low of 6C will mean for double the blankets tonight.
Thunderstorms are also on the cards for parts of the city - particularly west of Auckland.
A few showers can also be expected and there is a risk of hail in some parts too, the MetService said.
Tomorrow will bring finer weather for Auckland - but the clear skies would mean for a much colder night; with an overnight low of 3C forecast.
Meteorologist Tahlia Crabtree said the chilly temperatures and bad weather was due to a front moving from the lower part of the North Island - already getting "grotty" weather conditions this morning - towards the upper half of the country.
"By tonight, the front will have moved across Auckland. There will be a pretty unpleasant southerly," she said.
"But in true spring fashion, the front moves away [tomorrow] and we've got a ridge of high pressure coming in."
Similar conditions are expected in and around the Northland region.
The coldest place early this morning was in Tekapo, which recorded a teeth-chattering -6C.
Those in Invercargill experienced a chilly -1.5C when the latest observation was recorded at 7am.
Another cold spot was at Dunedin Airport, which got a -4.6C temperature.
Fire danger due to high winds
High winds in the Otago region have kept local firefighters busy the last few days and people are being warned to take extra safety precautions.
Fire crews were called to the Rock and Pillar Range yesterday evening when gale force winds fanned a fire through tussock grasslands.
The fire affected Department of Conservation land and spread onto nearby farmland.
Principal rural fire officer in the region, Graeme Still, said: "People need to be aware that any activity that involves fire during this heightened fire danger is asking for trouble and extra precautions need to be taken."
He said tussock grasslands and other light material throughout Otago are 100 per cent dry at the moment, so people need to be extra careful and think about what they are doing.
Although snow and rain has fallen in the area today, frosts and strong north-westerly winds are forecast in the region later this week.
"Frost pulls the moisture out of vegetation - making them highly combustible, so the danger has not decreased just because we have had a bit of rain," he said.
Anyone heading out camping should remember to never leave a camp stove unattended and to make sure the stove is on level ground to prevent from tipping over.
It is also recommended to place a camp stove where there is no vegetation in a 3m radius, such as on a stream bed or bare ground.
Road snowfall warnings
A number of road snowfall warnings are in place in the South Island, in particular, and road authorities are urging motorists to be prepared before heading out.
The NZ Transport Agency says although State Highway 73 Arthurs Pass to Otira is open, chains are essential.
"The road is closed to towing vehicles. Road users should be mindful of road cleaning crews in the area," an alert read.
Those travelling on SH77 Methven to Rakaia Gorge are being warned of ice affecting the route because of frosty temperatures there this morning.
"Please take care and drive to the conditions."
Ice is also expected on SH8 Burkes Pass to Twizel and motorists using the SH79 Fairlie to Rangitata route are also being advised to keep an eye out for snow and ice.
Meanwhile, restrictions have been lifted on SH73 Springfield to Castle Hill Porters Pass, and chains are no longer required.
The SH80 Aoraki Mt Cook Highway, which had been closed earlier, is also affected by snow but has reopened.
People driving on that road are being encouraged to stick to the 30km/h speed restriction in place at the moment due to the nearby fire damage in recent days. Fire and Emergency NZ staff are still on site.