Driving conditions in parts of west Wales remain treacherous following the first snowfall of the winter.
Dyfed-Powys Police advised drivers in Carmarthenshire and parts of Pembrokeshire to travel only if their journey was essential on Saturday.
The Highways Agency closed the A477 road to Pembroke Dock because of an accident on sheet ice.
Gwent Police also said some of the more remote roads in their area were icy and potentially dangerous.
It follows huge disruption on Friday after heavy snow fell in a band across mid, south and west Wales, forcing 460 schools to close and huge disruption on the roads.
A Dyfed-Powys Police spokesman said officers have attended numerous incidents throughout Carmarthenshire, where vehicles have skidded on black ice early on Saturday morning.
Heavier than expected snow fell across large parts of Wales
In one incident a lorry jack-knifed on the A40 between Carmarthen and St Clears.
Police say gritting lorries have been out all night but they are not having any affect in Carmarthenshire where black ice is causing major problems.
Gwent Police had to recover a vehicle from a mountain road between Manmoel and Cwm in Blaenau Gwent after it slid on black ice.
The A477 road in Pembrokeshire has been closed between Broadmoor and Redberth until 1300 GMT on Saturday.
Four people were struck by lightning in the Preseli mountains in Pembrokeshire, in a thunderstorm following Friday's snow.
One was transferred by helicopter to Morriston Hospital in Swansea while the three others were later discharged from hospital.
Forecasters admitted that snow in south and east Wales early on Friday was heavier than predicted.
Reports on Thursday suggested north and west Wales would be worst hit, with other areas receiving a light dusting of snow.
BBC Wales weatherman Derek Brockway said: "There was certainly more snow in the Vale of Glamorgan, the valleys and Cardiff than I thought there would be.
"But the Met Office had been warning of snow all week and had issued an early warning, so no-one should have been caught unawares."
A change in wind direction was probably to blame for the extra snow, Mr Brockway said, adding that no forecast could be 100% accurate.
Both Rhondda Cynon Taf and Bridgend councils said the snow had been worse than expected, but defended their responses in the face of criticism from one bus company.
Shamrock Coaches suspended its services in Bridgend, the Vale of Glamorgan and the valleys claiming roads had not been gritted. The company said it could not get buses out of depots.
Rhondda Cynon Taf Council said all roads had been salted by 0200 GMT on Friday.
But a statement added: "It appears that most snow fell after this time and we are now addressing the many problems this has caused by deploying all available resources including staff from other service areas."
Bridgend Council said the claim that roads had not been gritted was simply not correct.
"Precautionary salting was already carried out yesterday in anticipation of the forecasted light snowfall, but our response increased as the snow became heavier," the council said.