The impact would hit late today in the upper North Island after a mild, cloudy day.
The lower North Island would have rough conditions this afternoon: strong winds, cold and rain, with snowfall possible to 500m in the evening in the Remutaka Ranges.
Heavy rain and gale warnings are in place for the South Island and the lower North Island.
The MetService warned surface flooding, slips and rapidly rising rivers were possible in the Tararua Ranges and driving in the area could be hazardous, as 70mm to 100mm of rain was likely between 9am and 9pm today.
Road snow warnings are in place for most of the country. Lewis Pass, Porters Pass, Lindis Pass and Crown Range Rd are all likely to be affected by snow during the day, while later the Desert Rd and the Napier-Taupō Rd can expect snow tonight.
Severe frost and black ice are also possible in the lower South Island where cold winds will keep temperatures below 0degC overnight, Hines said.
Sunday's forecast is looking more positive. Most of the country looks fine by the afternoon as the frontal system pulls away.
Today's weather
Whangārei
Mostly cloudy, the odd shower. Rain developing evening. Northwesterlies. High 18C, Low 10C
Auckland
Mostly cloudy with isolated showers. Rain developing evening. Northwesterlies. High 17C, Low 8C
Hamilton
A few showers turning to rain in the evening. Northwesterlies dying out evening. High 16C, Low 6C
Tauranga
Increasing cloud with chance shower or two. Rain developing evening. Northwesterlies dying out at night. High 17C, Low 6C
New Plymouth
Showers turning to persistent rain afternoon, clearing at night. Northwesterlies changing strong southeast evening. High 15C, Low 6C
Napier
High cloud. Rain developing evening as northwest changes strong southerly. High 19C, Low 5C
Whanganui
The odd shower turning to rain afternoon, then easing evening. Northwesterlies change gusty southeast around evening. High 16C, Low 4C
Wellington
Rain developing late morning, briefly heavy, as strong northwest changes southerly. Easing to a few showers by evening, but winds rising to gale. High 13C, Low 5C
Nelson
Morning rain, then easing to a chance shower until evening. Strong northwest easing by afternoon, changing gusty southeast evening. High 13C, Low 0C
Christchurch
Rain easing to few showers afternoon. Snow to about 500 metres for Banks Peninsula. Southerlies, strong at times. High 10C, Low 2C
Dunedin
Rain easing to a few showers morning. Strong southerlies, easing by evening. High 9C, Low 3C