Heavy rain watches are in place for parts of the North Island, while the South Island experiences temperatures as low as -6.8 degrees.
MetService has issued heavy rain warnings for Northland, Auckland and the Coromandel Peninsula.
Northland's watch was due to expire at 10am although meteorologist Ngaire Wotherspoon said the region had had some "solid stuff" over it.
Auckland's watch was in place until 2pm, including Great Barrier Island, while Coromandel's was in place until midday on Saturday.
For Auckland, Wotherspoon said some localised downpours were possible with rainfall of between 25 millimetres and 40mm per hour.
A "complex frontal system" was coming down over the North Island causing a solid rainband, she said.
The East Coast of the North Island may experience some rain later this afternoon, but more was expected on Saturday, Wotherspoon said.
There were a "mixture of fronts and lows" bringing the wet weather.
South Island was looking "pretty good" although some patchy rain was expected around Fiordland and Canterbury, for example.
Temperatures had reached -6.8 in Tekapo as of 8am this morning, while Mount Cook airport hit -6.3 and Alexandra airport hit -5.1.
Queenstown hit -1 today, as Coronet Peak opens for the ski season.
Coronet Peak said it was having a "limited opening" and Meadows Express and Magic Carpets will open for skiing and riding.
Queenstown had some high cloud handing over it, stopping any dramatic drops in temperature, Wotherspoon said.