Metservice meteorologist Alwyn Bakker said the rain and snow were caused by a trough of low pressure moving eastward across Aotearoa.
"At higher levels of the atmosphere, particularly cold air will be making its way over Te Waipounamu.
"The cooling effect will be less noticeable at ground level, but the resulting atmospheric instability makes thunderstorms more likely, and snow is expected to three or four hundred metres in the south," he said.
About the Southern Alps, Kā Tiritiri o te Moana, the Lewis Pass SH7, Arthurs Pass SH73, Porters Pass SH73, and Lindis Pass SH8 as much as 6cm of snow was forecast to fall and settle at higher elevations.
Further south, the Haast Pass SH6, Crown Range Rd and Dunedin to Waitai Highway SH1 were also expected to see snow settle as low as 200m.
Unsettled weather is forecast across the country this week, with a strong and unstable westerly flow bringing snow and bands of rain to many regions.
"At this stage, the exact position of the low centre is uncertain, so as we progress through the week MetService advises keeping up to date with the latest forecasts," states Bakker.
Frosty conditions will continue to put a damper on spring for southern and central parts of the North Island this week, dusting Mt Taranaki with a layer of snow.
