The NOAA weather supercomputer generated image sequence below shows cold temperatures moving north over New Zealand at six hour intervals starting tomorrow morning.
The cold is being brought north by a Southerly which can be seen in the images in the form of isobars running vertically south to north. These will bring southerly winds over most of the country over the next 36 hours.
Temperatures are forecast to keep falling through Wednesday when temperatures in Wellington are expected to top out at just 8 degrees centigrade.
A similar high is also expected in the capital on Thursday with colder temperatures further inland, and much colder temperatures further south. Even in temperate Auckland temperatures on Thursday are not expected to make two figures.
As the following images show the prognosis is for the chill to linger with Wellington still forecast to achieve a high temperature of just nine degrees on Friday.
And if all this isn't bleak enough for you, the bad news is that this southerly spell is not forecast to bring either snow for skiers, or rain for the NZ's ailing hydro storage capacity.
+12 hours (tomorrow morning)
hours (Wednesday morning)
hours (Thursday morning)
hours (Friday morning)