People across parts of the UK have had their coldest November night since 2010, and have three more days of snow and ice warnings ahead of them.
Overnight temperatures in Prestwick, Ayrshire, fell to -5.5C (22F) and dropped to a bitter -6.1C (21F) in the Cumbrian town of Keswick.
On Aonach Mor in the Scottish Highlands, it was even colder at -8C.
Snow has fallen across Scotland and east England, as far south as Norfolk. It will stay cold for a few more days.
Freezing fog is making travel treacherous in parts of the Midlands, north-west England and Northern Ireland, and could develop elsewhere.
Later, more snow is expected in the north and east of Scotland, as well as the east of England. There is a chance of some falling overnight on the moors in south west England too.
In Northern Ireland, there has been a little rain and snow, dampening the ground. Combined with freezing fog, roads and pavements have been made icy. In north Wales there has been some sleet.
The current blasts of cold air are coming from Scandinavia where people are experiencing near-record cold November weather.
Overnight, some of the coldest places were:
Bridgefoot, in Cumbria -7.2C (19F)
Tyndrum in Crianlarich -5.8C (22F)
Hawarden in Flintshire -3 (27F)
Aldergrove, County Antrim -2.9C (27F)
The Met Office has issued weather warnings for snow and ice from 17:00 GMT on Wednesday for parts of northern and eastern Scotland, north-east England and Yorkshire.
A second set are in place on Thursday for eastern Scotland and north-east England down to North Yorkshire, and for most of the day in south-west England. Much of Northern Ireland is being warned about ice on Thursday.
The snow and ice warning has now been extended into Friday morning for most of the east coast of the UK.
These yellow graded warnings mean people could face hazardous conditions, with disruption and delays likely on roads and railways and icy patches on roads and pavements.
Drivers are being warned to take extra care, with many facing road closures. The A169 in Goathland in the North York Moors has been closed since last night, as has the A1671 between Whitby and Pickering.
Separately, the UK Health Security Agency has issued an amber cold-health alert for the health sector for northern regions of England, meaning "significant impacts are probable".
The amber alert indicates that the cold weather is likely to affect the whole health service, with the potential for the entire population to be at risk, the agency says.
A less severe yellow cold-health warning is in place for the Midlands. Both alerts are in force from 18:00 GMT on Tuesday until 5 December.
Dr Agostinho Sousa, from the agency, urged people to check on the vulnerable and told the over-65s and sick to heat their most-used rooms, like the living room or the bedroom.
