Two weather systems will "crash" into each other this weekend bringing strong winds and heavy rain.
WeatherWatch.co.nz said a large, slow moving high and a more energetic area of low pressure will create a squash zone of strong winds for central and eastern areas while heavy rain moves into the West Coast and some of the western North Island.
Clouds will continue to increase from the southwest today and Auckland's mainly clear skies over the past few days will be replaced by gloomy cloud from the Tasman Sea.
A sharp front extending from a large polar low pressure area pushes into southern coastal areas Friday and brings some rain and snow - mostly around Fiordland.
WeatherWatch.co.nz forecasts continuous rain around Fiordland over the weekend with over 150mm of precipitation over the next 24 hours.
This heavy rain will slide up the western side of NZ until about Taranaki - beyond that it looks much patchier and may not reach northern NZ until the very end of the weekend.
Strong northerlies will move on to the South Island over the days ahead, peaking this weekend around Cook Strait and then into the eastern ranges of the North Island. This will lead to warmer than normal temperatures and dry, sunny weather to the east, according to WeatherWatch.co.nz.
It was a slightly warmer morning for most of the country today, with the lowest temperature in Masterton with -3C.
Taupō also had a chilly start with -0.6C, and Christchurch fell just below zero, but most other areas stayed above freezing.
Wellington's low was 3.5C, while Dunedin started off at a amicable 6.7C, and Auckland stayed at a comfortable 10C.
However, MetService meteorologist Andrew James said a frontal system approaching from the west would bring wet weather to western areas of the South Island today.
The North Island is looking mostly fine, with some cloudy areas and some showers for the Gisborne area, he said.
On Friday and Saturday, the rain will settle in with the chance of warning criteria in Fiordland, southern Westland and the headwaters of the Canterbury and Otago lakes and rivers.
In addition, severe gale northwesterlies may affect exposed parts of Fiordland, Southland and Otago on Friday, and the Canterbury High Country on Saturday.
The wet weather in the South Island will also spread north tomorrow, affecting western areas south of Taranaki, James said.
Through the weekend there will be a worsening trend for the North Island, with showers turning heavy in western parts.
Cloudy periods. Light winds. High 14C / Low 6C.
Auckland: Cloudy periods. Light winds. High 14C / Low 5C.
Tauranga: Fine with light winds. High 14C / Low 3C.
Hamilton: Fine, apart from morning frosts and fog. Light winds. High 13C / Low 0C.
New Plymouth: Fine with some high cloud and light winds. High 13C / Low 4C.
Napier: Cloudy periods. Light winds. High 13C / Low 0C.
Wellington: Fine, some morning cloud. Northerlies developing evening. High 12C / Low 7C.
Nelson: Fine with high cloud and morning frosts. Light winds. High 13C / Low 2C.
Christchurch: Early frosts and cloudy periods - low cloud morning and high cloud from afternoon. Northerlies developing morning. High 10C / Low 2C.
Dunedin: Morning cloud and chance shower, then fine with high cloud. Northeast turning northwest evening. High 11C / Low 8C.