MetService said the front, preceded by a moist northwesterly flow, was expected to move over the south of the South Island from early on Sunday, with a low then forming a front to the west of Westland.
The front and low would then move northeast over central and northern parts of New Zealand from Sunday afternoon to early on Monday, bringing rain to most places, with brief heavy falls likely in the west of the South Island.
Much colder southerly winds follow the front, which should bring the snow level down to around 400 to 500 metres in Canterbury, Otago, Southland and Fiordland.
It was likely that several of the higher South Island roads would be affected by snow, and high country farmers in Otago and Canterbury were advised to prepare for the potential of significant snowfall.
MetService updated warnings for most alpine roads late on Sunday morning to advise of less snow than previously forecast, particularly for Canterbury alpine roads, which had been expected to get up to 20cm of snow.
However, more snow was now expected on the Crown Range from about 10am today. MetService said 5 to 10cm of snow (or more) may settle on the road near the summit, with lesser amounts to 500 metres.
The road linking Queenstown and Wanaka was temporarily closed after a vehicle got stuck on Sunday afternoon, but was reopen by 2pm.
In a Facebook post, the Queenstown Lakes District Council said the closure was from Cardrona Village to Eastburn Rd and crews worked to clear the road.
"We're asking that chains still be fitted at this stage due to current conditions."
Conditions were fine on the alternative route via Cromwell for those without chains.
Grit had been applied near the summit of the Crown Range and extra caution was advised.
"Temperatures are dropping, with ice is expected to form in other areas of the road. Crews will continue to monitor the situation. Remember, if you regularly travel over the Crown Range chains should be carried all winter."
In Central Otago, snow in the Maniototo area was settling on the roads, a spokesman for the Central Otago District Council said about 2.15pm today.
Crews were out ploughing and gritting, and road users should drive to winter conditions.
A snow watch was in place for the Canterbury High Country, about and north of Rangitata River, from 4pm on Sunday until 1am on Monday. Snow may lower to 400 metres, with heavy snow expected above 700 metres.
People are advised to keep up-to-date with the latest forecasts, snow warnings and to take care on the roads during the long weekend.
Snow for alpine roads
MetService late on Sunday morning revised down warnings for most alpine roads. Just snow showers were now expected for the Milford Road (State Highway 94) in Southland.
Further north, snow was set to affect Canterbury alpine passes including Porters Pass (SH73), which may get up to 8cm and Arthur's Pass (SH73), which was forecast to get up to 5cm on Sunday evening until Monday morning.
Milford Road (SH94)
From 11am until 2pm: A few light snow showers on Sunday but little, if anything, is expected to settle on the road.
Crown Range Road
From 11am until 2pm: 5 to 10cm of snow (or more) may settle on the road near the summit on Sunday, with lesser amounts to 500 metres.
Lindis Pass (SH8)
From 11am until 2pm: Snow to 500 metres on Sunday. Some 5 to 10cm of snow (or more) may settle on the road above 700 metres, with lesser amounts lower down.
Porters Pass (SH73)
From 4pm on Sunday until 6am on Monday: Snow is forecast to lower to 700 metres on Sunday afternoon, and 2 to 8cm of snow may settle on the road near the summit, with lesser amounts lower down.
Arthurs Pass (SH73)
From 5pm on Sunday until 6am on Monday: Snow expected to lower to 700 metres on Sunday afternoon, and 3 to 5cm of snow may settle on the road near the summit, with lesser amounts down.
Lewis Pass (SH7)
From 8pm on Sunday until 8am on Monday: Snow is forecast to lower to 700 metres on Sunday evening, and 3 to 5cm of snow may settle on the road near the summit, with lesser amounts lower down.
