"Snow showers are expected overnight Saturday above 800m. Between 10pm Saturday and 4am Sunday, 2cm to 3cm of snow may settle about the higher parts of the road," MetService said.
MetService meteorologist Raveen Das said the Desert Road was the only one of four highways across the country with Road Snowfall Warnings that was unlikely to clear overnight.
Temperatures in the Taupo region are set to get down to 1C overnight.
The three other highways with MetService Road Snowfall Warnings are all in the South Island.
Lewis Pass (SH7), which crosses the Southern Alps to link the West Coast Region with Canterbury, has had snow throughout this afternoon.
"Snow is expected to continue through to early this afternoon. Expect a further 5cm to 10cm of snow to accumulate on the road above 600m between 10am and 4pm Saturday, and lesser amounts lower down," MetService said.
Arthur's Pass (SH73) connecting Christchurch on the east coast with Cass/Hokitika via the Southern Alps likewise has had afternoon snow.
"Snow is expected to affect the road until early this afternoon. From 10am to 1pm Saturday, a further 1cm to 2cm of snow may accumulate on the road above 700m with lesser amounts lower down," MetService said.
Porters Pass (SH73) also has a snowfall warning with a forecast of 5cm to 10cm of snow to accumulate about the higher parts of the road and lesser amounts down to 400m up until 10pm tonight.
The temperature in Christchurch is forecast to hit 0C overnight.
An update on all these Road Snowfall warnings will come in at 10pm tonight.
Das said all three South Island highways with snowfall warnings are "likely to ease this evening".
"The overall trend for this evening is for snow showers to ease, the clearance really happens overnight, so there might be a few snow flurries affecting those roads," Das said.
Also in Canterbury rockfall closed SH1 from Oaro to Peketa at 3.30pm today.
NZTA updated at 5.35pm that route 70 (Kaikoura Inland Route) is also closed from Mount Lyford to Kaikoura due to snow, and with no detour available, motorists are asked to avoid the area.
The Canterbury town of Kaiapoi has also had widespread surface flooding today, after 90mm of rain overnight.
MetService reports indicate the worst of the rain for Kaiapoi is over and there is low chance of further rain tomorrow.
"Sucker trucks are working flat out across the district to make sure the waste and stormwater systems are running at 100 per cent so water can be cleared in the coming hours through our infrastructure network," the Waimakariri District Council informed Kaiapoi residents.
