New amber alerts for snow have been issued by forecasters, covering much of northern Scotland, starting on Sunday evening.
The Met Office said another 5-10cm (2-4ins) could fall fairly widely in the north east, Highlands and Northern Isles while a few places on the mainland could possibly see 20-30cm (8-12ins).
Widespread snow accumulations in recent days have already led to treacherous driving conditions with numerous reports of vehicles getting stuck.
The new alerts, which also warn of strong winds, run from 18:00 and continue until 10:00 on Monday when many schools are due to reopen after the holiday. Councils are reviewing the whether that will happen.
Highland Council said road conditions in Easter Ross, Sutherland and Caithness were particularly challenging, with drifting and freezing conditions overnight, and it advised people to travel only if it was essential.
The A9 and A99 between Helmsdale to Wick remained closed due to heavy snow, poor visibility and drifting.
Some 32 gritters were sent out in Aberdeenshire on Sunday morning but parts of the road network were still said to be “impassable”.
Network Rail said heavy snow in areas such as Kintore in Aberdeenshire, had seen snowploughs dispatched to clear the railway line, as well as further north on the line to Wick.
One of its snowploughs encountered drifts up to 1.2m (4ft) deep near Laurencekirk.
Loganair has cancelled a number of Sunday flights but Aberdeen Airport remained open.
A spokesperson said: “With weather warnings in place we urge passengers to check the status of their flight with their airline before they travel to the airport.”
All schools in Shetland will be closed on Monday as a result of the amber warnings.
Aberdeen City Council has said the reopening of its schools would be delayed until 11:00 on Monday due to uncertainty about the weather conditions, and breakfast clubs will not open.
