Snowfalls across many parts of Wales meant an unexpected St David's Day holiday for children as more than 400 schools were closed.
Roads were closed and trains cancelled, while some St David's Day celebrations were called off due to the bad weather.
With further snow and ice forecast across many parts of Wales, councils said gritters would operate overnight.
Temperatures are predicted to fall to -5C during the night and drivers were warned to expect difficult conditions.
After heavy snowfall on Tuesday night and Wednesday morning, several St David's Day celebrations were cancelled across Wales.
Conditions were reported to be worst in the south Wales valleys, Carmarthenshire, Gwynedd and the Swansea area.
Many children enjoyed St David's Day at home
A number of trains were cancelled in south Wales early in the morning, while there were speed restrictions along the M4 because of the weather, and a section of the A5 in north Wales closed for a few hours following an accident.
Gwent Police said there were bad conditions on the A465 Heads of the Valleys road.
People in some areas did not receive their post due to the snow.
A spokeswoman for the Royal Mail apologised and said once the extreme weather is over they hoped to resume normal service as soon as possible.
Also on Wednesday, the North Glamorgan NHS Trust announced that it had decided to cancel all non-emergency patient activity such as outpatient clinics, elective surgery and day case surgery scheduled for Thursday.
Snow fall early in Mumbles on Wednesday
The trust said the cancellations would apply to Prince Charles Hospital, Aberdare Hospital, Mountain Ash Hospital, St Tydfil's Hospital and Seymour Berry Centre.
Patients will be given re-arranged dates as quickly as possible, it said.
Bad weather for Thursday has been forecast across many parts of Wales.
BBC Wales weatherman Derek Brockway said: "We aren't out of the woods. There is likely to be heavy snow in some areas - particularly on the higher ground.
"Parts of north and west Wales will see the worst with up to 10cm in some places.
"Ice will also be a problem. Temperatures could drop to -5C, causing problems on untreated roads."
Late on Wednesday, the Met Office issued a severe weather warning for Thursday, forecasting snow and icy roads in Cardiff, Newport, Pembrokeshire and the Vale of Glamorgan.
In Carmarthenshire, snow, hail and sub-zero temperatures were forecast for Wednesday night and Thursday morning, particularly in eastern parts of the county.
Carmarthenshire Council said gritters would be out throughout the night on main roads and priority routes, but warned there could be some icy patches.
Refuse collections are not expected to take place on Thursday with crews helping to clear footways and car parks.
The council added that many schools could be closed and urged parents to ensure they had arrangements in place for their children.
In north Wales, Gwynedd Council said it would continue gritting with heavy snowfall expected.
It added that driving conditions on some minor roads could be difficult on Thursday morning.
Ceredigion Council said it would also keep gritters out overnight to combat expected snowfalls.
"Gritters have been out continuously in a 12-hour shift pattern since midnight on Monday night. They will continue to grit and clear the primary routes throughout the evening."