People planning to head out this weekend to watch a fireworks show to celebrate Guy Fawkes should take a jacket or pack a rug.
A series of cold fronts began heading across New Zealand last night and will continue moving over most of the country this morning, bringing chilly temperatures.
Weather Watch chief analyst Philip Duncan said five cold fronts would replace the humid air over northern New Zealand with drier, cooler air from the southwest today and the coming weekend.
"Each one gets colder as it comes through, so it's sort of like walking down steps - as each one comes past, it gets colder. Then when the next one comes past, it drops and flattens out a little bit. It just gradually gets colder and colder over the next 24 hours."
MetService said Aucklanders should expect lows of about 12C tonight and 9C tomorrow, Guy Fawkes Day.
The national weather service said it should be reasonably rain-free with the odd shower and southwest winds.
Mr Duncan said the cold air moving off the Antarctic ice shelves meant this weekend would feel like winter in Otago and Southland. "We'll see snow probably in Queenstown and down in Cromwell and sleet in Invercargill - it's kind of weird for November."
He said the worst of the frosty weather system should have moved off the country by tomorrow afternoon, but the cold air would linger.
The east of New Zealand, from Canterbury to the Coromandel, should have "pretty mild" temperatures, but most of the country would definitely be cooler than it had been.
Mr Duncan said it was also likely to be very windy this weekend.
"We've had it pretty mild for the last few weeks, so this will probably be a surprise for most people."
But the good news was it should start to warm up again on Sunday as the cold fronts moved off and it should be warm "wherever you are".