Weather: Heavy frosts incoming as temperatures in south set to plummet

Get the longjohns out!
Get the longjohns out! Photo credit: WeatherWatch / Getty.

It will be a winter wonderland across the South Island over the coming days with some of the "heaviest frosts" of the year likely to roll in.

WeatherWatch forecasts the whole island will be affected by frosts this weekend, with temperatures also set to plummet. 

Coastal areas of Southland could get down to -1C, and further inland the mercury will drop to -3C. As you head towards the mountains and spots like Tekapo, it could hit -5C overnight Saturday while it will be as low as -4C across the Canterbury plans. Darfield is forecast to see a low of -3C and Ashburton is at -1C.

"Light frosts will stretch to coastal parts of Otago and Canterbury but some coastal fringes may just have enough of a breeze to limit frosts for all," WeatherWatch says.

While it will be chilly down south, the further north you go, the milder it gets. 

Light frosts can be expected in some sheltered areas in the weekend, with Hutt Valley dropping to 2C, the Wairarapa and Manawatu at 1C, Taupo at 2C and Rotorua at 3C.

"However parts of the upper North Island are in the double-digits for overnight lows this weekend, or at least very close to the 10C mark," Weatherwatch says.

"Auckland City dips down to 11C on Sunday night, some further rural areas of the region may get down to 4C. Other northern centres have lows between 11C and 8C degrees this weekend."

There will also be eyes on snowfall levels. Currently, MetService has a road snowfall warning in place for Lindis Pass, Milford Rd and Crown Range Rd in the south. That's on top of a heavy rain watch for much of the West Coast. 

"A front is set to bring heavy rain to Westland, and a watch has been issued - comes into force at 11am, and remains through to the early hours of Friday. Also, snow showers could settle on some higher roads. Stay safe," MetService says.