The police are urging motorists to be prepared as further snowstorms are expected overnight.
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Motorists are being urged to prepare for icy roads and reminded to drive to the conditions.
The Central District police said with the combination of clearer weather today and plummeting overnight temperatures they are preparing for some icy road conditions this evening, overnight and stretching into mid-morning Thursday.
Drivers are being encouraged to be equally prepared. Central District Road Policing Manager, acting Inspector Nigel Allan, said motorists, particularly those overnight such as long haul drivers and early morning commuters, will need to take extreme care.
"Keep a wary eye out for any patches on the road that appear wet will likely be ice and should be treated as such."
He said higher locations such as Saddle Road, Pahiatua Track, Mount Bruce and Norsewood are expecting snow and driving to the conditions is key.
People are advised to check their vehicles and tyres are roadworthy before heading off, and ensure all windows are completely clear of ice.
The police are also recommending that drivers ensure they carry a fully charged mobile phone and have a blanket, snacks and water on hand in case of an emergency or a breakdown.
People are being warned to prepare for a cold spell over the next few days as the freezing weather begins to bite across the country.
A MetService duty meterologist Nick Zachar said overnight freezing levels will drop for much of the country in what he describes as a robust winter storm.
"From Ashburton northwards along the east coast all the way from Waiarapa, and even in the Gisborne area, the higher parts will see some snow showers and towns and cities closer to sea level will be more sleety."
Snow and ice affected roads earlier today
The police in Christchurch were bracing themselves for a morning of snow and ice-related incidents as freezing weather hit the region.
They warned motorists there are pockets of ice in sheltered areas and to adjust their following distances and allow time to get to where they are going to avoid problems.
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Inspector Al Stewart, the Canterbury Road policing manager, said the roads were slippery in places and drivers should slow down and drive to the conditions.
"We've got a lot of ice on our roads this morning, unfortunately when we saw this a couple of weeks ago we'd had 3 times our average daily crashes before 8 o'clock in the morning, we're trying to get those messages out there to drivers to please slow down and make sure you're getting to where you're going safely this morning."
Inspector Stewart asked people to spend time clearing their windscreens of frost properly before they begin driving.
The snow and rain which has fallen in the hills of Christchurch has turned to ice. The Port Hills received the heaviest falls with lower lying suburbs getting a dusting.
Christchurch City Council roading engineer Richard Bailey told Morning Report there were a lot of grit trucks out in the city and drivers needed to be patient and drive more slowly.
"Some are interfering with our grit trucks, which is causing the workers a few problems," he said.
Gritting trucks crews around the city said some cars cutting in front of their trucks were making their job difficult.
"[Commuters are] travelling too close behind the grit, I don't know if they realise that we are actually spreading grit and of course the trucks have to stop spreading grit when the vehicles get to close," Mr Bailey said.
The police last night reported multiple-vehicle crashes in the Queenstown Lakes area, Southland and also around Dunedin.
The Southern District police were also urging motorists to delay non-essential travel.
They said road conditions were less than ideal across the district with black ice in Invercargill to snow in Dunedin and Central Otago.
The Transport Agency said snow and ice were affecting most state highways in the lower South Island.
There have also been a number of weather-related crashes on the road.
A petrol tanker sliding off the road was just one of ten crashes Waikato police attended to over-night due to icy conditions.
The 10 crashes happened from four-thirty last night to seven-thirty, this morning.
Shortly before 6am, a LPG tanker slided off the road and came to a stop in a ditch, the driver was not hurt.
North of Hamilton a car has crashed on Horsham Downs Road, causing an oil spill which was affecting traction on the road.
District road policing manager inspector Freda Grace said drivers needed to watch their speed, lengthen their following distances and drive to the conditions.