A colder southerly flow is moving up and over New Zealand today and tomorrow, with temperatures below normal in many regions.
Increasing high pressure from the west will also bring lighter winds and colder nights – with frosts expected through inland parts of both islands, but especially the southern half of the South Island.
WeatherWatch.co.nz has Below Zero temperature maps (https://www.weatherwatch.co.nz/maps-radars/temperature/below-zero) showing a frost risk for tonight across the South Island’s interior:
While the Upper North Island will have a temperature drop today, it will be more noticeable tonight and Wednesday morning. Tuesday is below average temperaturewise over the lower two thirds of the nation but overnight tonight all of NZ will be below average.
On Wednesday it will be colder to start with but as the day wears on temperatures slowly start to return to normal (although some pockets will still be below normal).
Wednesday night will be another cold night going into Thursday morning with more frosts possible as high pressure grows, locking in the colder air.
Drier than usual weather will also be setting in as this powerful high pressure belt moves in (and will linger for the first week of May).