Drivers are being warned to take extra care over the next few days as exceptionally low temperatures hit the area.

Tonight (Thursday) road temperatures could drop to minus 8 degrees or even lower, bringing a warning from the county council that even gritted roads could freeze.

Stuart Pile, executive member for highways and transport at Herts County Council said: “While salt is the best material we have available to treat snow and ice, it isn’t a magic powder that always makes roads completely safe. The way salt works is that it turns ice into salt water, which has a lower freezing point, and the melted water then drains away. However, once temperatures drop to minus six or below - as is possible in the next couple of days - the salt water itself freezes.”

“When temperatures get really low, we add grit to the salt so that the action of tyres on the road breaks up the packed snow and ice,” added Cllr Pile. “This is why roads with more traffic clear quicker than those with fewer vehicles, even when they have had exactly the same amount of salt and grit put on them.”

A council spokesman said since the early hours of Tuesday morning Hertfordshire Highways has salted all main routes in the county (A and B roads, one road into each village and major bus routes) five times, as well as working to clear ice and snow from high priority pavements and refilling salt bins. A further salting run of main routes is planned for 7pm tonight.

“Such low temperatures obviously lead to hazardous driving conditions so if you’re travelling please be very careful. If you do have to drive, please leave plenty of room between you and the vehicle in front, steer and brake very gently and reduce your overall speed.

“Pedestrians are also asked to take a great deal of care on pavements and when crossing the road. We’re expecting this cold spell to continue for another week or so. Please take care when you’re out and about.”