It will be settled weather in the North Island today after a wet and windy night that resulted in power outages and emergency callouts in Auckland.
However, the west coast of the South Island is set to be drenched by up to 200mm of rain in 24 hours.
A strong, moist northwest flow would cover the South Island today and tomorrow, bringing rain to western areas, MetService said.
"Rain is expected to become heavy in Fiordland on Friday, and 200mm or possibly more could accumulate there by Saturday evening."
A heavy rain warning is in place for Fiordland from 6pm tonight through to 6pm Saturday with up 200mm of rain expected to accumulate.
More rain was expected in the area after Saturday.
A strong wind watch was also in place for southern Fiordland, Southland, Clutha, Southern Lakes, Central Otago and Dunedin from 6pm tonight to 11am Saturday.
Winds could reach gale force at this time, MetService said.
Looking ahead, an active front was forecast to move across the South Island from the west on Saturday, then across the North Island on Sunday.
There was a high-risk rainfall could reach warning amounts about Fiordland, the Otago and Canterbury Headwaters, Westland, Buller, and western Nelson on Saturday, with a moderate to low risk about the Tararua Range, northern Taranaki and the King Country from Saturday to Sunday.
On Sunday, there was a low risk of severe northwest gales about southern Taranaki, Wanganui, Taihape, Hawkes Bay and Gisborne.
Last night Auckland emergency services dealt with a number of weather-related incidents, including power outages, across the city.
MetService meteorologist Ravi Kandula told the Herald Auckland had a mean wind speed of around 50 to 60km/h, with some gusts reaching 100km/h.
Outages occurred at several different locations around the city and wider Vector network, according to the Vector Outage Map.
A police spokeswoman said they have received a number of calls from the public about wind-related incidents.
"We've had a number of calls about fencing, timber, other material from building sites blowing on to the road – Takapuna, Otahuhu," she said.
"We've had a few reports of trees or branches blocking roads – Kohimarama, Epsom, Mt Roskill, Clendon Park, Kumeu, Waitoki, Northwestern motorway, Pukekohe."
Parts of Titirangi, Mt Eden and into Kingsland, Herne Bay, and two areas of Otahuhu were experiencing outages at 9.20pm.
Muriwai through Waimauku and towards Taupaki lost power too, as did an area of Whangaparaoa near Gulf Harbour.
Small pockets of power had also been lost near Puhoi, Warkworth, Tauhoa, and Wellsford.
Whangārei: Fine with southwesterlies. High 19C Low 9C
Auckland: Fine and mostly sunny. Fresh southwesterlies. High 17C Low 12C
Tauranga: Fine and clear. Southwesterlies. High 21C Low 9C
Whanganui: Fine. Westerlies. High 18C Low 10C
Napier: Fine. Southwesterlies dying away. High 18C Low 8C
Wellington: Fine, apart from morning and evening cloud. Southerlies die away this morning, northerlies strengthen tonight. High 16C Low 11C
Christchurch: Fine this morning. Becoming cloudy this afternoon. Northeasterlies by midday. High 17C Low 9C
Dunedin : Fine start. Becoming cloudy this afternoon and light rain developing this evening. Northerlies, strengthening tonight. High 16C Low 11C