The first major cold snap has arrived in the south with temperatures dropping below minus six in some parts, and there are warnings the mercury could drop further.
MetService said more cold nights are on the way and frost has already arrived in the south.
MetService's Lisa Murray said this is the "first really cold snap we've felt" this year.
Residents in Dunedin woke to a chilly morning with locals rugging up - including Dante the dog, who wrapped up for walkies in his woollies.
"It's been a little bit icy and freezing as well," Dante's owner said.
"It was a bit chilly, I had a hoodie on this morning but it's warmed up a wee bit now," one local said.
"It always comes with a shock to the system when it does get so cold," another added.
But the cold didn't stop one brave golfer from getting out for 18 holes on the course on Thursday morning.
The middle of the South Island was home to some of the coldest temperatures so far this year.
"It was -6.8C at Mt Cook Airport, we've seen -3C in Queenstown and -6C at Dunedin Airport," Murray said.
Passengers there are not going far thanks to the frost and fog.
Dunedin Airport customer experience manager Chris Snow said they were forced to cancel two flights on Thursday and several on Wednesday night because of fog.
Murray said a ridge of high pressure has meant clear skies - but cold temperatures.
"It means that our skies are generally clear and we don't have that warm cloud blanket over us keeping us warm at night, all the heat radiates off."
After a mild autumn and record-breaking warmth in May, many people will be hoping this winter doesn't set records of a different kind.
