Freezing weather is set to grip the UK, prompting treacherous conditions on the roads and possible delays at airports across Britain.
Temperatures will plummet overnight with northern parts most likely to face disruption on Tuesday morning, the Met Office said.
Wintry conditions will continue into the weekend amid warning Britain could face an unusually cold snap for the rest of the month.
"There are indications of quite a prolonged cold period," Met Office forecaster Alex Burkill said, with this week predicted to be one of the coldest of the winter so far.
Temperatures could drop to -6C in parts of northern England and the midlands early Tuesday morning, the Met Office said.
A band of rain, sleet and snow will sweep in across Scotland and Northern Ireland overnight.
Between 1cm and 3cm of snow will fall widely and hilly areas could see up to 5cm, before the weather pushes into northern England and Wales.
Snow and ice warnings have been issued for swathes of the country over the next two days.
It comes after snow showers left between 1cm and 2cm in Kent and Essex on Monday and caused several crashes on the M20.
"As we go through the next 24 to 48 hours, it's going to stay cold, and we are going to see some snow and pretty much anywhere in the country could see something," Burkill said.
"Across a big chunk of Scotland and Northern Ireland, where we have had snow overnight, that's likely to then lead to some ice in time for morning rush hour tomorrow.
"Across northern parts of England and Wales we are likely to have some snow falling during morning rush hour, so that's likely to cause some difficult driving conditions and there could also be some icy patches too."
British Airways said 70 short-haul flights to and from London's Heathrow airport did not operate on Monday due to the weather and a further 10 have been cancelled on Tuesday.
Temperatures will dip further on Tuesday night - and could sink as low as -11C in parts of Scotland and northern England.
Another band of snow, sleet and rain would sweep across the country from Wednesday to Thursday and bring a "milder blip" in the weather, Burkill said, adding: "The cold weather is likely to return as we go towards the weekend.
"Really much of February and perhaps even into March it is going to stay on the cold side, so temperatures generally below average, with further frosts and also the risk of rain, sleet and snow as well."