An amber weather warning means there is the possibility of travel delays, road and rail closures, power cuts and the potential risk to life and property, according to the Met Office.
Yellow weather warnings for ice are in place in north-western Scotland and the Northern and Western Isles, alerting travellers to be wary of slippery roads. In Devon, the county council has urged people to get home soon and stay put.
As the cold snap continues Hastings has been issued with a warning to expect "heavy snow" this evening (Thursday, January 31).
One to three inches is likely to accumulate quickly - within two to three hours - with up to four cm in some places.
Snow is lying at least 12cm deep on Bodmin Moor in Cornwall, and 5cm has been recorded in Sennybridge, Powys, according to the Met Office.
Several departures from London City Airport were delayed this morning due to poor visibility a day after airports in Manchester and Liverpool were forced to delay flights due to heavy snow.More news: Threatening cold to bring 'dangerous to impossible travel conditions' this week
Details: Areas of snow are expected Thursday onwards into early Friday.
Met Office meteorologist Mark Wilson said: "On Thursday it will be generally dry in the north".
Central England and Wales could bear the brunt of the snow on Thursday afternoon and into the evening as wet weather coming through the south-west England turns wintry, with some places seeing up to 4in of snow.
- A chance of injuries from slips and falls on icy surfaces.
The Met Office said rain and snow were expected to move into the United Kingdom from the southwest from Thursday and through Friday with icy patches forming, but that snow amounts would "vary markedly" across England and Wales. "Ice is likely in many parts overnight".