Northerly winds from the Arctic will bring freezing temperatures to large parts of the UK, with snow showers affecting Scotland, Northern Ireland, parts of northern England, north Wales and the east coast from Thursday.
It could be -4°C overnight on Thursday in parts of Scotland.
"The winds will turn more northerly on Thursday afternoon through Friday, bringing cold air down from the Arctic and with that it will also be very unsettled with snow showers," said Rachel Vince, senior meteorologist with MeteoGroup, the weather division of the Press Association.
"Because it is northerly and north-westerly winds, it is largely northern and western Scotland that will get the snow showers.
"It will turn milder at the weekend so I would not expect it to last very much beyond Saturday, Sunday."
Snow is forecast for the far north of Scotland from around lunchtime on Thursday, moving south through Thursday night.
The hills of northern Scotland could see several centimetres of snow, with up to 4cm (almost two inches) elsewhere. Temperatures will reach a maximum of 10°C (50°F) on Thursday with temperatures over- night on Thursday falling as low as -4°C, or 25°F, in Scotland.
"Temperatures on Friday will stay below zero in parts of Scotland and generally between 4°C and 7°C (39°F and 45°F) elsewhere, but it will feel a lot colder because of the cold northerly wind," Miss Vince said.
"It will become comparatively milder for the start of next week."