The return of snow and ice is causing major disruption to the transport network across Wales.
Almost 900 schools closed on Friday, bus services were suspended in many areas and there were delays on trains.
Some hospital appointments have been cancelled and the ambulance service is having difficulties.
Weekend fixtures and events are already being postponed amid warnings of further severe ice and snow bringing treacherous conditions late on Friday.
In Cardiff, the council said its Winter Wonderland outside City Hall, which includes an open air ice rink, is closed due to the severe weather.
North and west Wales have been badly affected by the second band of snow to hit the county this month with reports of up to 12 inches (30cm) falling in some parts.
Traffic Wales has warned people not to drive if possible and bus services in many areas have been suspended and there are delays to some train services.
Speed restrictions of 30mph were in place on much of the M4.
A number of weekend sporting fixtures are set to be hit, with Cardiff City's Championship match at home to Burnley postponed.
Cardiff Bus says it will be operating on main roads only.
In south Wales, the A470 has been reported as just passable but with hazardous driving conditions in parts.
Traffic in the centre of Bangor, Gwynedd, was reported as being at a standstill because of the snow and funeral services at the town's crematorium had to be cancelled.
Routine operations and clinics at Ysbyty Gwynedd were postponed while coastguard teams used 4 x 4 vehicles to drive some stranded staff to work. There were no bin collections across the county and all libraries were closed.
Conditions were bad on the A5 from Llandegai and the road was passable only in 4x4 vehicles.
There were delays to Arriva Trains Wales services.
The Hereford to Newport, Holyhead to Chester, Pwllheli to Shrewsbury, Wrexham central to Chester, Carmarthen to Cardiff train lines were all experiencing delays due to "signalling problems" caused by the weather.
Rhondda Cynon Taf has issued advice asking residents not to leave their homes or drive unless it is an emergency situation.
The Welsh Ambulance Service said it was "encountering difficulties" in maintaining a normal service for routine patient transport across Wales.
A spokesman said it was concentrating its service on "specially identified patients only, who are of clinical risk such as renal and cancer patients".
Patients should only contact 999 for an ambulance for a life-threatening emergency, he said.
Blood supplies have been hit badly by the weather. The Welsh Blood Service said it had very few donors turn up and all types of blood was running low.
Donors are urged to take advantage of any break in the bad weather to go and give blood.
Up to 12in (30cm) of snow fell overnight in Anglesey and Gwynedd and up to 7in (18cm) in the Towy Valley in west Wales.
In mid Wales, Ceredigion council appealed to drivers not to set out unless their journey was absolutely essential.
Bus services in Swansea, Neath, Port Talbot, Bridgend and Maesteg areas were suspended. Buses in Cardiff were running but some routes may have been shortened.
There were also no buses running from the Llanelli, Ammanford or Carmarthen depots.
Cardiff Airport was open with most flights operating as normal but passengers are advised to contact their airline or tour operator before travelling to the airport.
Routine surgery and clinics have been cancelled at Ysbyty Gwynedd in Bangor.
Temperatures are expected to drop as low as -6 (21F) by Friday night and lower than that in rural areas.
BBC Wales weather presenter Behnaz Akhgar said more snow is forecast for the next day or so with a severe weather warning for ice and snow still in place.
"Snow showers will continue for much of the day and will be heavy at times.
"Much of the heavy stuff will be in north and west Wales with perhaps the odd spot of brightness in the east.
"Temperatures at their best are 2C (36F) but factor in the winds and it will feel much colder."
Further snow is likely but by Tuesday the weather should become drier.
Friday evening marks the annual peak of the Christmas party season dubbed "Black Friday" by emergency services.
Police urged caution among party-goers over personal safety.
Supt Phil Davies, of South Wales Police, said: "With the wintry weather forecast for the coming days we would encourage everyone to extra care to keep themselves safe."
Those braving the cold have been urged to use NHS services responsibly during the busiest season of the year.
Dr Kesh Baboolal, of Cardiff and Vale University Health Board said: "We are not asking people to stop going out and having a good time.
"The recent increase in the number of flu cases and the problems likely to occur as a result of the forecast bad weather will mean NHS staff across our services working to full capacity.
"Add into the mix people who end up in A&E with alcohol-related injuries and we are expecting a large increase in demand on our services.
Meanwhile, Royal Mail has planned thousands of extra deliveries this Sunday to combat the deliveries hampered by the severe weather.
Up to 7,000 delivery rounds serving more than a million homes are planned.