"In fact, the east of both islands are up to several degrees above average."
A high pressure system out to the west of New Zealand is bringing warmer westerly winds to those parts and would mean warmer than average daytime temperatures.
"We've got a quiet couple of days coming up, but there's another surge of rain and snow and wind for the weekend.
"The nights are still a little bit cool," Duncan said.
"But as we get to Saturday, there is a southerly on the way for the lower South Island."
By tomorrow afternoon, rain returns to the West Coast and later on in Southland. There will also be strong southerly winds in the area later on that day.
"So you've got a cold Friday night and a wintry Saturday on the way.
People in Southland and central Otago areas could expect daytime highs to drop to temperatures between 4C to 6C.
Snow levels in Southland may be as low as 100m or 200m.
In Otago, those snow levels are forecast to be about 200m or 300m - while Canterbury should have snow to 500m lowering to 300m later in the day, possibly to 200m for a time, Weather Watch said.
For those in the North Island, there will be pockets of warmer than average weather on Saturday, Duncan said.
But colder southeast winds take a dive on Sunday.
"A good example is Napier, which has a high of 17C on Saturday but just 9C on Sunday.''
Many people around the North Island are enjoying fine spells, save for some light showers now and again.
Northland, Auckland and Waikato to Manawatū - including the central high country - are all experiencing sunny spells today. However, cloudy conditions and some showers are on the cards.
Gisborne to Wairarapa, including the Bay of Plenty, are seeing the same conditions. While Horowhenua to Wellington get some cloud and one or two showers today.
Further south, those in Marlborough, Nelson and Canterbury are enjoying mostly fine weather. While in Buller and Westland, people can expect a partly cloudy day with isolated showers.
Anyone in Otago and Southland is in for a fine day also.
SEVERE WEATHER WARNING:
The MetService has issued a severe weather warning for the west of the South Island, where heavy rains are forecast.
A front moving northeast is expected to move on to the South Island from tomorrow. "This front should bring a period of heavy rain to Fiordland and Westland during [tomorrow] and Saturday."
As a result, people living in these areas are being warned that rainfall accumulations may approach "warning criteria".
There is also a heavy rain watch for the Westland ranges south of Otira for between 8am tomorrow to 10am on Saturday.
Above 1000m, most of this will fall as snow, MetService said. Rainfall here may also reach warning criteria.
The same warning has been issued for Fiordland for overnight and through to the early hours of Saturday morning.
SEVERE WEATHER OUTLOOK:
Going into the start of the weekend, an active front is forecast to move up the South Island from tomorrow and will bring heavy rain to western areas.
MetService has issued a severe weather outlook as a result.
"Behind the front, much colder air should spread up eastern parts of the South Island during Saturday, while moist air aloft continues to stream down from the northwest.
"This could bring snow to quite low levels and, at this stage, there is low confidence of significant widespread snowfall meeting warning criteria from Southland to Marlborough and late Saturday in Wairarapa too.''
By Sunday, rain is expected to spread farther up the North Island. Snow is expected down to 600m over central and eastern areas and there is "low confidence" that snow amounts will meet warning criteria, MetService said.
"Also on Sunday, south to southeast gales are likely over much of the North Island, with low confidence that they might become severe."
