MetService meteorologist Michael Pawley said fine spells, particularly in the morning, and a few showers were forecast across Otago and Southland on Christmas Day.
A high of 19°C was forecast in Dunedin.
Wānaka and Queenstown were expecting highs of 17°C and 16°C, respectively, about 4°C lower than average highs for the time of year, Mr Pawley said.
However, a high of 17°C was forecast in Invercargill — "that’s a bit closer to average for them".
"It’s looking better [in the South] than it is in Westland. As you go further north, it could be a bit finer."
A front moving up the West Coast this week was expected to bring heavy rain to Greymouth and Buller.
"It depends a lot on how much that can get over into the east of the [Southern] Alps," he said.
"But certainly for places like [the] South, it’s more of a showery situation."
On Christmas Day, Christchurch was forecast to be a cloudy 25°C, Wellington was forecast to be 20°C and mainly fine and Auckland to be a cloudy 24°C.
