Monday will be a mostly sunny day countrywide, thanks to the large high pressure ridge spreading south. It will be short lived – tomorrow sees heavy rain return to the West Coast and windier northerlies developing across New Zealand.
Rain on West Coast will begin by Monday night and persist through Tuesday night. The total rain during Monday night and Tuesday daytime will reach around 60 mm. Higher up and heavy snow accumulation is possible over the Southern Alps on Tuesday.
The area of showery/patchy rain will move to the western part of the North Island with less intensity by Tuesday night. Rain is not likely to penetrate the eastern side of the South Island to any significant degree but a few spits are possible.
On Tuesday &/or Wednesday Marlborough, Canterbury, and Otago will be sunny and significantly warmer than usual. Max temperature in Christchurch on Wednesday will be 17C, which is 6C higher than today.
The mild weather lasts until Thursday and Friday when a cool down occurs thanks to a southerly injection. We first mentioned this last week, since then the models have eased back on this southerly and no longer does it pose as a “polar” snap, but certainly a temperature drop back to normal, or even slightly below normal in some pockets by Friday.