Motorists are being warned to drive carefully as icy Arctic air sweeps Scotland – bringing treacherous conditions with it.

A yellow weather alert for snow and ice is in force across northern Scotland and has been extended until 12pm on Sunday.

The Met Office has also issued a yellow warning for ice across southern Scotland until noon on Friday.

Snow was disrupting travel on Friday morning, with snow gates closed on the A939 at Cock Bridge snow gate and the B974 at Cairn O’Mount in Aberdeenshire, Traffic Scotland said.

In Dumfries and Galloway, Nithsdale Police tweeted: “A weather warning remains in place for ice. Fully defrost all windows before driving & drive to the conditions.”

Scotland is braced for freezing temperatures, with warnings they could drop as low as minus 10C overnight in some areas.

Forecasters said accumulations of 2-5cm of snow are possible at lower levels in the yellow snow and ice warning area, with 10-15cm above 200 metres, especially across the North Highlands, Moray and Aberdeenshire.

The Met Office warning said: “Some drifting and blizzard conditions are possible on hill routes at first. In addition, ice is likely to form on untreated surfaces, mainly where some of the showers fall as rain or sleet on some coasts.”

Some roads and railways are likely to be affected, with longer journey times by road, bus and train, it said.

Many schools in the Aberdeenshire area were closed on Thursday and some schools in the Highlands were partly shut on Friday.

Aberdeenshire Council urged people to plan ahead if they are travelling over the weekend.

Network Rail said a normal service is planned across Scotland on Friday but, with cold temperatures expected into next week, a call will be held to go over the detailed weather forecast.

Gritters will be ensuring roads are treated throughout Friday.