The Met Office has issued two rare amber snow alerts as part of nine weather warnings stretching from Cornwall to the Outer Hebrides.
Snow is expected to bring particular difficulty in North East England, North West England, SW Scotland & Lothian Borders, Strathcylde and Yorkshire & Humber.
The warning, which could cause some disruption due to a "spell of heavy snow", was issued at 7am and will last until midday.
The UK's national weather service said: "Heavy snow will spread northeastwards on Saturday morning giving significant accumulations, especially on hills.
The Met Office has issued two rare amber snow alerts as part of nine weather warnings stretching from Cornwall to the Outer Hebrides
PA/MET OFFICE
"Temporary accumulations of 5-10 cm are possible in the Vale of York, with 10-20 cm on ground typically above 200m, and potentially as much as 20-30 cm on hills above 400m.
"Snow will eventually change to rain in all areas by Saturday afternoon, but may be preceded by a short spell of freezing rain in places adding to the ice risk.
"Strengthening winds will lead to drifting of lying snow, with difficult travelling conditions likely on higher level routes, and the risk of interruptions to power supplies.
"A fairly rapid thaw of lying snow is then likely later on Saturday and overnight as milder air moves in.
The Met Office issued several alerts across the weekend
MET OFFICE
A snow and ice amber warning covering Central, Tayside & Fife, Grampian, Highlands & Eilean Siar and Strathclyde will also cause problems between 7am and 5pm.
The UK's national weather service said to expect accumulations of up to 20 cm, with as much as 40 cm possible on hills above 400m.
The Met Office's remaining seven weather warnings include three yellow wind warnings, two rain and snow alerts and two rain alerts.
Most of the UK is impacted by the alerts, including the South West, South East of England, East Midlands, Wales and Northern Ireland.
Snow in YorkshirePAYellow alerts for rain and snow in Scotland and the North of England, rain in Wales and rain and wind across the south coast remain in place until Sunday.
However, mercury is expected to return closer to average after days of sub-zero temperatures.
Looking ahead to the period between November 27 and December 6, the Met Office said: "Probably a quieter interlude to start this period for much of the UK as high pressure builds across the north with a return of night frosts.
"However there is still a risk of some rain across southern parts of the country on Wednesday, although the northern extent of this is uncertain.
"The high is likely to migrate eastwards during the second half of next week, potentially allowing some outbreaks of rain to move into some some northwestern areas along with some stronger winds.
"Into December, and while signals are mixed it looks most likely that high pressure may re-assert itself close to or over the UK, with temperatures generally near average, but some overnight frost is likely, and rather cold by day where any fog persists."
