A good covering of snow is forecast for north and west Wales

North, west and mid Wales are likely to be most affected overnight with heavy snow unlikely in the south east.

With temperatures below freezing expected, councils are getting ready to grit roads and send out snow ploughs.

Stena Line confirmed it was cancelling all ferry services from Holyhead to Dun Laoghaire because of the bad weather.

The Met Office said heavy wintry showers affecting Scotland on Thursday afternoon would move into west Wales later and on into Friday morning.

Rain and sleet

The Highways Agency warned drivers to prepare themselves and their cars and to slow down on roads.

BBC Wales weather presenter Derek Brockway said snow would fall across Anglesey, Gwynedd, Conwy, Denbighshire and Flintshire on Friday morning.

It is also likely across Ceredigion, Pembrokeshire, Carmarthenshire, Neath and Swansea, although much of the south-east could escape.

"It could be here for the rush hour on Friday morning, but it may turn more to rain and sleet in the afternoon," he said.

He added that parts of the north and west could wake up a to a "good covering" of snow on Friday, with further hail and snow showers likely during the day.

The wind will also be strong on the northern and westerly coasts on Friday. While the highest temperature will be about 6C, wind chill will make that feel more like minus 5C.

It is the responsibility of local authorities to grit the roads and keep them clear, and both Anglesey and Gwynedd Council said they were monitoring the weather and were well prepared.

'Huge risks'

Carmarthenshire Council said it had 10,000 tonnes of salt stocked in barns ready for spreading on roads and a fleet of 28 gritting lorries on standby.

The council said priority would be given to clearing trunk and primary roads.

And Cardiff Council confirmed its winter maintenance team was ready to ensure roads and motorways were clear from ice and snow.

Executive Member for Transportation Elgan Morgan advised drivers: "Stay alert, be in control and adjust your driving to suit the conditions.

"These are probably pretty obvious observations to make, but we all too often see drivers taking huge risks when the weather is bad."