Wind chills as low as -20 this morning in exposed parts of Southland and overnight lows down to -7 predicted tonight across the North Island’s volcanic plateau clearly indicate the cold as being the main factor with this fast moving shot of polar air.

WeatherWatch.co.nz reports as of 7am the wind chill factor in Invercargill was -7 with -7 also in exposed parts of Dunedin and -8 in Queenstown.

Exposed ranges around northern Southland are estimated to be currently as low as -20.

Highs of only 3 to 7 degrees are expected across southern and eastern parts of the South Island today.

In Auckland tonight temperatures are expected to drop to 2 or 3 degrees with frosts in rural places around the city possible.  Frosty conditions look set to return to Waikato tonight. 

-7 is possible in Waiouru tonight.

Tomorrow places like Hamilton and Auckand can expect to only reach 11 or 12 degrees with a high of 8 or 9 for Wellington.

The capital is likely to have a wind chill of near zero when that southerly arrives today.