However, some may get slightly warmer due to a northwesterly prior to the drop.
South Islanders could see a few frosts inland if winds ease.
As for the heavy rain, it will also be the West Coast in the firing line which develops today and continues into tomorrow.
It could cause flooding and slips, as between 150mm to 200mm is forecast to fall.
Snow, up to 20cm, will only fall in alpine areas.
Weatherwatch.co.nz said severe gales, some up to 100km/h at times, were likely in marine areas, especially in the South Island.
The MetService has also issued heavy rain warnings for Fiordland, Westland, Buller, and the Canterbury and Otago headwaters, and a warning is in force for these areas.
