It is set to be a foggy start to Christmas Day in parts of Scotland.
The Met Office said that fog or freezing fog patches which is dense in places were expected.
Visibility could be cut to 50 metres in the worst-hit areas.
The Met Office added: “Fog or freezing fog patches will quickly become more widespread later on Christmas Eve and will also be dense in places.
“Not everywhere will see fog, but where it does form, the visibility may fall to around 50 metres at times.
“Fog will tend to be thin and lift in western and some central areas overnight, but will be slow to clear on Christmas Day in the east.
Forecasters warned the dense fog patches could affect Christmas travel plans.
There could be longer journey times for anyone who still needs to make a trip out.
Temperatures will struggle if the fog sticks but there could be some brightness across East Anglia, Kent and particularly north-east Scotland.
It could be quite a mild Christmas Day with temperatures of about 8C in Edinburgh, London, Birmingham and Manchester, 6C in Norwich, 11C in Belfast and Cardiff and 12C in Plymouth.