A front is expected to move onto the far south of the South Island on Monday, then move quickly north over the remainder of southern and central New Zealand on Tuesday, before weakening and stalling over northern New Zealand on Wednesday, says a Metservice spokesperson.

This front is also likely to be preceded by a period of heavy rain in the west, and strong to gale force northwest winds in exposed places.

For Fiordland and the ranges of Westland south of the glaciers there is low confidence that rainfall accumulations will meet warning criteria on Monday, rising to moderate on Tuesday. There is low confidence of heavy rain for the ranges of Westland from the glaciers to Otira on Tuesday.

On Monday, there is low confidence that nt to northwest gales could become severe over parts of Fiordland, Southland and Otago, and on Tuesday that extends northwards through the Canterbury High Country, as indicated on the chart. Also on Tuesday, there is moderate confidence of severe northwest gales over Wairarapa.

MetService says that as the front moves over southern and central New Zealand on Tuesday it is followed by a strong and cold southerly wind change.

"This could bring snow down to around 700 metres over parts of the South Island, with the potential to affect higher roads and high country farms," says a MetService spokesperson.