The Met Office says low lying areas could see one to two centimetres of snow while the hills could see up to 10cms fall in 12 hours.
"Three to 5cm of snow is likely above 200 metres, with up to 10cm in a few places".
Sarah Kent, of the Met Office, said: 'We've got cold weather throughout the United Kingdom for most of the week.
The yellow warning, the lowest level, runs from 12noon on Tuesday (29 January) to 11am on Wednesday (30 January).
Along with travel disruption, including delayed or cancelled rail and air travel, the Met Office has also highlighted there could be power cuts, as people brace themselves for the onslaught.
Temperature-wise, it's going to be cold, with readings hovering between 2°C and -2°C.
"Temperatures will be below freezing generally". There could be snow showers in London, but they are unlikely to settle.
Despite the low figures, eastern Scotland is set for sunshine this afternoon, whereas western parts of Scotland will still grapple with snow showers.
Largely sunny but cold with a widespread frost, breezy nearer the coast during the morning.
It was previously predicted that up to four inches of snow may fall across parts of South, East and central England from 9pm on Tuesday until midday Wednesday.
Heavy snow is also expected over Northern Ireland, southern Scotland and North Wales.
"For higher ground in Wales and northern-England could see the higher totals of 9-10cm by Thursday morning".