Gritters are out treating the roads in Somerset on Wednesday as the road temperature is set to drop below minus 4C.

It follows a warning about icy weather covering parts of West Somerset as a national health alert was issued because of the cold. The road temperature in the county is predicted to fall below 4 degrees C.

Travel Somerset, which issues updates on behalf of the county council highways team, said: “With temperatures dropping and weather warnings in place, gritters will be out this afternoon on all routes, as well as in the early morning. Very cold, with a risk of hoar frost.”

There are weather stations across Somerset and the department receives special daily forecasts to predict road surface temperatures and air moisture content. Gritting is usually carried out before road surface temperatures are predicted to drop below 1C and frost or ice is expected to form on the road.

The county council is responsible for gritting roads in Somerset according to a set of priorities, except for the M5, A303 and A36 which are treated by Highways England.

The Exeter-based Met Office is warning of disruption to road and rail travel due to icy conditions, and says people may be at risk of injuries from falls on pavements. The alert for snow and ice runs from 5pm on Wednesday, December 7, to 6pm on Thursday.

The area covered by the weather alert runs over the northern half of the Westcountry from Cornwall into Somerset, including Exmoor. It comes as the UK Health Security Agency has issued a level three cold weather alert across the country from 6pm on Wednesday to 9am on Monday.

Overnight lows of minus 10C (14F) are predicted in northern Scotland, Wales, Northern Ireland and the east coast. The national health alert has been triggered because severe cold weather is likely to have a significant effect on people’s health, especially those with underlying conditions.

Somerset County Council’s public health team is encouraging people to keep warm and look out for people at risk from the effects of the cold.