"Through the southern half of the North Island, for Taranaki down to Wellington and including the Wairarapa, it's going to be a little chilly in the morning. A light southerly wind will bring a bit of cloud which means a little bit of a gloomy start, but as the day progresses it should brighten up significantly and have a nice sunny afternoon."
Central areas of the North Island may be in for Christmas showers.
"We're talking inland parts of Bay of Plenty, inland parts of Hawke's Bay as well as Rotorua, Taupō and Taihape. Some of the afternoon showers could be fairly heavy and we couldn't even rule out a rumble of thunder or too in those central areas."
The South Island can expect a bit of a chilly start and cloud in the morning, but the majority of areas can expect to brighten up for a nice and sunny afternoon.
"Maybe a Christmas barbecue at lunchtime or in the evening will certainly be on the cards there.
"In terms of rain in the South Island on Christmas, central parts of Nelson and Marlborough will see some showers throughout the middle of the day with nice weather for the remainder."
On Boxing Day, most of the North Island will be treated to a fine summer's day.
Hines expects more warm and sunny weather for the top half of the North Island, likely to still see a few showers in some places such as Bay of Plenty and Gisborne.
"But no one is lining up that much rain on the 26th, expect it to be light and not stick around for too long."
The South Island changes a little bit more, come Boxing Day.
For eastern regions, that means things get a little bit windier but with a significant temperature spike.
"It'll be 6, 7 or 8 degrees warmer on the 26th than it is on Christmas for the likes of Christchurch and other parts of Canterbury."
"Although the flip side of that is people on the western side of the South Island look likely to see showers on Boxing Day. If you're in Fiordland, more serious rain will be hitting you."
The excitement of Christmas can be over the top for some children and a good way to get them to burn off the excess energy while staying cool in the midsummer heat is to spend an hour at the Waterworld floating waterpark.
Kids at Browns Bay on Auckland's North Shore bounced over obstacles and splashed down slides as temperatures hit the mid-20s yesterday, helping, no doubt, to keep their minds off what Santa might bring tonight.
The waterpark emphasises safety for confident swimmers aged 5 and above and everyone must wear the lifejackets provided.
Under the current Covid restrictions, only the vaccinated over 12s can participate and all Waterworld staff are vaccinated.
There are three parks operating across Auckland over the summer months, moving location every six days.