The Highways Agency and police are warning of heavy snow fall across East Devon today.
Many routes are only passable with care after a night in which many cars were abandoned in the Blackdown Hills, with snow continuing to settle.
The A30 near Honiton is all but reduced to one lane due to the weather while roads through the Blackdown Hills are hazardous due to ice and snow.
Several cars remain snowbound on the A303 between Ilminster and Marsh and police are in attendance.
A police spokesperson said: "Drivers in East Devon are advised not to travel unless absolutely necessary.
"Snow is still falling in the area, making driving conditions extremely hazardous and we advise motorists to make only essential journeys.
"Road conditions are said to be difficult anywhere east of Honiton – particularly on the A375 Honiton to Sidmouth Road and the A3052 in the Seaton area."
One motorist who was travelling from Woodbury to Plymouth today said: "There's thick snow and fog on the A38 at Haldon Hill and conditions are changing continuously. The gritting lorry drivers have done a great job and the road is passable."
Snow is causing problems on the A380 at Telegraph Hill in both directions at Ashcombe. This has forced the closure of one lane.
On the M5, at junction 28 at Cullompton, there one lane blocked in both directions due to hazardous driving conditions.
An accident involving four vehicles closed a section of the A35 between Springfield Road and New Road.
Police were called to the scene at 12:14pm and have called a recovery vehicle to remove the damaged cars.
No injuries were reported to police.
The A3052 at Trow Hill in Sidford has been reported to police as being just about passable.
The road has been reopened for the time being but motorists are advised to use extreme caution.
The Highways Agency reported an accident on Bridge Road in Exeter, which caused problems for outbound traffic.
It is still snowing in East and Mid-Devon this evening and road conditions are still difficult in places.
Police are still advising drivers only to make essential journeys.