Drivers have been warned to expect hazardous conditions in the early hours as fog envelops the county.

The warning - issued this afternoon - predicts a thick blanket of fog from midnight until 10am on Saturday.

The Met Offfice says not everywhere will see fog, but where it does form visibility will fall below 100 metres in places, and perhaps below 50 metres in a few spots.

The fog could lead to travel disruption and difficult driving conditions.

The chief forecaster said: "Clear skies and light winds will allow temperatures to drop on Friday night, leading to fog formation in many places.

"Some areas of cloud will prevent fog from forming in some spots, making the fog rather more patchy than was the case on Friday morning.

"However, where it does form, it is likely to be equally dense, and traffic passing in and out of areas of reduced visibility prove a hazard in itself.

"Fog will then mostly lift by mid morning but may very locally last until midday in a few prone spots."