Travellers embarking on the great Christmas getaway have been warned to prepare for disruption as Storm Barbara approaches Scotland.
Around 100 offshore workers may not get home for Christmas due to weather west of Shetland, BP has warned.
Ferries have also been cancelled as winds pick up on the west coast.
The full effect of the storm is expected to be felt on Friday and Saturday, when gusts of up to 90mph are forecast in the north and west.
Gusts of up to 70mph are also expected on Christmas Day, forecasters warned.
An amber "be prepared" warning is in force from 12:00 on Friday to 06:00 on Christmas Eve.
It said strong winds in the north west could cause structural damage, as well as disruption to power supplies and travel.
A yellow "be aware" warning for wind is also in place on Wednesday, Thursday and on Christmas Day.
In other developments:
- Scottish and Southern Electricity Networks said it was moving engineers to areas it expected to be hit by the storm;
- Ferry companies have warned passengers to prepare for "severe disruption" in the lead up to Christmas;
- Loganair said it would waive charges for passengers who wanted to transfer pre-booked tickets to earlier flights in a bid to avoid disruption;
- Comhairle nan Eilean Siar, the Western Isles council, warned people to "travel with care" on Friday and Saturday;
- It also asked residents and construction workers to secure loose debris and scaffolding;
- The UK coastguard warned against taking risks to photograph the weather. "A dramatic photograph or selfie is not worth risking your life for," they said.
About 100 BP workers could be stranded offshore over Christmas if the poor weather delays a scheduled crew changeover.
A spokesman for the oil firm said: "As we often see this time of year, the weather west of Shetland is becoming increasingly challenging with current sea swells of over 6 meters (20ft) and due to rise to over 20 metres (65ft) at the weekend.
"Unfortunately, this means that we will be unable to carry out our usual crew change flights before Christmas.
"Whilst we appreciate this will be extremely disappointing for those impacted, we are committed to putting the safety of our people above all else."
Guidelines issued by the Civil Aviation Authority (CAA) prohibit flights where the sea state if over six metres.
RMT regional organiser Jake Molloy said the weather conditions could affect many more oil workers due onshore for Christmas.
"It's difficult at any time but all the worse at this time of year for the crews," he said.
"Now they're doing three week shifts, it means their trip will extend into a fourth. It's a long time to be away from home at any time of year."
Meanwhile passengers on 20 of Caledonian MacBrayne's 26 ferry routes around the west coast were warned to expect disruption on Wednesday.
Forecasts of gusts of up to 46mph have meant that a number of sailings from Mallaig and Barra were cancelled.
Cold and blustery westerly winds were expected to bring heavy and frequent wintry showers across northern and western Scotland on Wednesday and Thursday.
Gales were likely at times along the west coast and the Northern Isles with winds gusting to around 55mph, while snow was expected on upland areas, with 5cm to 10cm (2-4in) possible on higher routes across the western and central Highlands.
The Met Office said frequent lightning may be an additional hazard across the Northern and Western Isles and the west coast in particular with the potential for disruption to power supplies.
Met Office spokeswoman Nicola Maxey said: "There will be blustery westerly winds coming through with heavy frequent wintry showers and we could see accumulations of snow on higher ground and maybe some slushy stuff at lower levels.
"We also expect some lightning and the chance of some icy roads. The lightning could also affect power supplies and there may be some power cuts.
"That is a weather system that is coming through from Wednesday to Thursday."
On Tuesday Transport Minister Humza Yousaf said the Scottish government was working with agencies to do everything possible to help get people safely to where they want to be.