Snow has fallen across much of the UK overnight, with forecasters warning that there is likely to be more later.
Overnight snow descended in north-east England, Manchester and north Wales and headed down towards the Midlands, with similar conditions in southern England.
With wintry conditions in Wales, Scotland and Northern Ireland, the Met Office has issued a number of flash warnings of severe or extreme weather.
BBC Weather warned driving would be "treacherous" in many areas.
Snow has also started to fall in central London.
Up to 8cm (3in) of snow is likely to fall in parts of southern England, according to BBC weather forecaster Chris Fawkes.
Icy roads
He also predicted heavy snow in all parts of Wales, with Scotland and Northern Ireland also likely to be hit by wintry conditions.
Where driving is concerned, the forecaster added: "The mix of snow and ice has created treacherous conditions in some parts of the country."
However, he said the snow was likely to clear in southern England later in the morning.
The Met Office said there was at least an 80% chance of heavy snow and widespread icy roads across Northern Ireland, north Wales and north-west England.
It also said there was a strong possibility of heavy snow in the West Midlands and southern England.
Aircraft search
The M56 has been closed in both directions in Cheshire, and there have been accidents on the M40.
A Thames Valley Police spokesman said Bicester, Aylesbury and Oxfordshire had all seen heavy snowfall, with several reports of cars struggling to continue their journeys and minor accidents.
Snow in Scotland and parts of northern England on Saturday hampered the search for a missing aircraft in the Highlands.
The light aircraft disappeared off radar as it was crossing the Cairngorms, south east of Glenmore Forest, in poor weather on Saturday morning.
Temperatures have dropped significantly over the weekend after a warm week that had included the hottest day of the year on Thursday.
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