Big chill begins with early snow
The earliest widespread snowfall for 17 years looked to be taking hold after parts of the country were blanketed in white.
Up to 4ins (10cm) of snow settled in north-east Scotland and northern England overnight, with accumulations also reported in Wales and Northern Ireland.
Amid sub-zero temperatures, the Met Office issued severe weather warnings, flagging up icy roads and drifting snow for the eastern side of the country as well as parts of Wales and Northern Ireland.
Forecasters warned the cold snap was expected to tighten its grip as the week continued, with temperatures dropping to minus 5C in some regions over the next few days. It is expected to be the earliest major snowfall since 1993.
Worst-hit is forecast to be the Scottish Highlands - with up to 8ins (20cm) eventually settling in Grampian - and in Yorkshire, the North East and East Anglia.
Early morning drivers found conditions difficult in parts of the North East where a blanket of snow was laying. Motorists reported problems on the main routes into Tyneside, with drivers reporting some roads were not gritted.
By the end of the week a moderate dusting of snow is expected across the rest of the country, though it will remain heaviest in Scotland, Orkney and the Shetland Isles. Temperatures were not expected to rise much above 2-5C by day, remaining lower in the more exposed, rural areas.
Billy Payne, a forecaster with MeteoGroup, the weather division of the Press Association, said: "It's going to be a very cold day. There will be sleet and snow showers around, with the worst affected areas in northern and eastern Scotland and north-east England. There will be a covering of snow, especially over the higher ground, with wintry showers across London."
He added: "The cold spell looks set to stay at least into the beginning of December. There will be low temperatures into next week, with the risk of sleet and snow showers."
The impending snow sparked a surge in rock salt sales of 1,600%, DIY chain B&Q reported. Wellington boots were also flying off the shelves, with sales up by 388% on last year's figure, and bosses said the store had stocked up on grit.