"The kids may not care much but the parents or grandparents might."
Coastal areas of both islands may be exposed to cloudy areas and breezy colder winds this weekend, while other neighbouring regions will be hot and sunny.
Whether to party indoors or out at Christmas may be one of those decisions you can't make until the day itself.
"The mountains and ranges make all the difference this weekend and one slight change in the wind angle can make a big difference between whether or not it will be cloud-free or cloudy," Duncan said.
"A cool and sometimes windy south to south west flow means places like Southland, Coastal Otago and Dunedin, Wellington and Auckland may be a little cloudy and windy.
"On the flip side, other regions will be protected by the hills and ranges and may have a fairly sunny hot day - like Gisborne, Hawke's Bay, Nelson, Marlborough and inland areas like Taupo and Wanaka."
Snow sports fans should note there has been snow falling at Mt Ruapehu this week, an unusual event for this time of the year.
"Snow on the mountain is not very common in December but it does happen from time to time due to NZ being two small islands in the roaring 40s," Duncan said.
"At the moment, despite La Nina, our weather pattern is still mostly being dominated by weather from the Southern Ocean.
"About a decade ago we had snow all over the South Island ranges and to low levels around Queenstown just before Christmas, so it does happen. Most people don't like it though!"
Next week sees a lot of high pressure over the country, in particular northern New Zealand.
And a deep small low near the South Island later in the week will create a short burst of wind and rain for some in the south.
It might be as well to look out a warm coat for New Year's Eve, Duncan said.
"The day before may see high pressure starting to fade - and the forecast for New Year's Eve does look a bit unsettled and windy with a potential cold front moving up the South island.
"The most settled weather may be in the north for New Year's Eve."
Christmas and New Year temperatures - supplied by MetService:
Whangarei
Christmas Day: High 22C, low 14
Boxing Day: High 2C3, low 12C
New Year's Eve: High 25C, low 15C
New Year's Day: High 20C
Auckland
Christmas Day: High 20C, low 15C
Boxing Day: High 21C, low 15C
New Year's Eve: High 20C, low 16C
New Year's Day: High 20C
Tauranga
Christmas Day: High 23C, low 13C
Boxing Day: High 23C, low 13C
New Year's Eve: High 23C, low 14C
New Year's Day: High 22C
Rotorua
Christmas Day: High 22C, low 9C
Boxing Day: High 22C, low 10C
New Year's Eve: High 22C, low 12C
New Year's Day: High 21C
Napier
Christmas Day: High 22C, low 12C
Boxing Day: High 22C, low 13C
New Year's Eve: High 25C, low 13C
New Year's Day: High 24C
Wellington
Christmas Day: High 18C, low 11C
Boxing Day: High 19C, low 13C
New Year's Eve: High 17C, low 14C
New Year's Day: HigH 17C
Christchurch
Christmas Day: High 20C, low 11C
Boxing Day: High 20C, low 10C
New Year's Eve: High 23C, low 11C
New Year's Day: High 21C
Dunedin
Christmas Day: High 17C, low 10C
Boxing Day: High 20C, low 13C
New Year's Eve: High 16C, low 10C
New Year's Day: High 15C
