According to WeatherWatch, coastal parts of Southland and Otago will experience windchill hovering around freezing on Monday afternoon, with -5C possible in the more exposed coastal areas such as Dunedin/Coastal Otago.
Further inland amid higher elevation the windchills intensify, and exposed parts of northern Southland and the hills around Otago will drop to -10C on Monday night.
This is colder than the North Pole is right now, which is in its summer season and experiencing windchill around -6C.
The bitterly cold air around the Southern Alps will mean windchill of -15C to -20C on Monday overnight and into Tuesday morning.
For the southern half of the West Coast the angle of the attacking winds may push some valleys well below zero with windchill.
WeatherWatch reports from Hokitika northwards a somewhat "milder" wind should come off the sea.
The forecaster warns livestock even on the West Coast should be protected from the bitterly cold air that may come down from the Southern Alps, especially south of Hokitika.
Snow-affected roads
Lewis Pass
Monday, 7am to 2pm
Forecast: Snow is forecast to affect the road. Expect 6cm-9cm of snow to settle near the summit with lesser amounts down to 600m.
Arthur's Pass
Monday, 6am to 1pm
Forecast: Snow expected to affect the road. Expect 1cm-3cm of snow to settle on the road near the summit with lesser amounts to 600m.
Porters Pass
Monday, 6am to 1pm
Forecast: A few snow showers are forecast to affect the road during the morning. About 1cm of snow may settle near the summit.
Haast Pass
Monday, 5am to 2pm
Forecast: A few snow showers may affect the road. Expect 1cm-3cm of snow to settle near the summit and lesser amounts down to 300m.
Lindis Pass
Monday, 6am to 11pm
Forecast: Snow is forecast to affect the road at times. Expect 6cm-8cm of snow to accumulate above 500m and lesser amounts at lower levels.
Crown Range Rd
Monday 3am to Tuesday 2am
Forecast: Snow is forecast to affect the road from early Monday morning to early Tuesday morning. Expect 4cm-6cm of snow to settle.
Milford Rd
Monday, 3am to 7pm
Forecast: Snow is forecast to affect the road from overnight tonight through to Monday night. Expect 15cm-20cm of snow to settle above 500m and lesser amounts down to 100m.
Dunedin to Waitati Highway
Monday 3pm to Tuesday 7am
Forecast: Snow showers are forecast to affect the road during Monday and early Tuesday morning. Expect 2cm to 4cm of snow to settle above 200m and lesser amounts at lower levels.
Source: MetService
Monday's forecast
Whangārei
Cloudy periods and a few showers. Northwesterlies turning southwest in the afternoon. High 17C, low 10C.
Auckland
Cloudy periods and a few showers. Northwesterlies turning fresh southwest in the afternoon. High 17C, low 9C.
Hamilton
Mostly cloudy with a few showers. Northwesterlies turning southwest by afternoon. High 16C, low 6C.
Tauranga
Cloudy periods. A shower or two, mainly in the afternoon. Westerlies. High 17C, low 7C.
Whanganui
Cloudy and showery. Strong westerlies. High 15C, low 5C.
Wellington
Partly cloudy. A few showers from afternoon as strong northwesterlies change southwest. High 14C, low 5C.
Christchurch
Morning showers, then fine. However, showers persist about Banks Peninsula, with sleet about high ground. Cold southwesterlies, strong in exposed places. High 12C, low 2C.
Dunedin
Showers. Snow to low levels. Strong cold southwesterlies, gale near the coast. High 9C, low 3C.
Invercargill
Periods of rain. Possible snow. Strong cold southwesterlies, gale at times. High 7C, low 3C
Source: MetService
