The Met Office has raised its prepared alerts up a notch to amber, with winter weather due to hit many areas tonight.
Fresh snow is expected later, with as much as 10cm falling in Glasgow and the central belt.
The alerts have been issued for Dumfries & Galloway, Strathclyde, Lothian & Borders, Central, Fife, Tayside, southern parts of Grampian and south Highland, and were due to remain in force until the early hours of Saturday morning.
Drivers have been advised to take care on the roads amid plunging temperatures and icy and slippery conditions.
The Scottish Government's Multi-Agency Response Team, based in the Traffic Scotland Control Centre in Glasgow, has been tasked with monitoring conditions and providing assistance across the network.
Transport Minister Keith Brown said: "According to the latest forecast, a combination of freezing temperatures, hard packed ice and fresh snow will mean a testing journey for some people tomorrow.
"I would urge the public to take on board police advice about driving to the conditions, planning ahead and taking notice of travel updates.
"Despite the high level of service and winter treatments provided, sudden weather changes can occur, and stopping distances increase tenfold when driving in snow and ice."
Assistant Chief Constable Allan Moffat, speaking on behalf of the Association of Chief Police Officers in Scotland, said: "There is now an amber warning in place for large areas of Scotland which will be affected by snow and ice and where there may be travel disruption.
"This means that people should be prepared for severe weather conditions and make appropriate arrangements. We would urge people to be aware of the threat of disruption and to check with radio and TV bulletins and online before making their journey.
"It is also important that the advice and warnings given to those wishing to travel in the areas affected are heeded as the conditions may be hazardous."
Forecasters say that the snow will last until Sunday, when warmer weather is expected to arrive. Temperatures could climb to around 5 degrees by the end of the weekend, bringing a thaw and an end to the freezing conditions.
In Orkney, police warned of the dangers of rescuing pets in the frozen conditions after a dog fell through ice.
Northern Constabulary said it was advising the public to be "particularly cautious" regarding frozen rivers and other water.
The labrador was rescued from the Peedie Sea, an inland lake at Kirkwall. Police and firemen attended to assist with the rescue of the dog, which was unable to pull itself out of the water after chasing a swan and falling through the ice.
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