Motorists in Bristol, Bath and north Somerset are being warned to avoid making unnecessary journeys as icy road conditions continue.
A severe weather warning has been issued for further snow and ice.
Parts of the M5 are only passable with extreme care, but two lanes are now open in both directions between Gordano services and Exeter.
Bristol Airport remains open, but passengers have been warned there may be disruption to flights.
A spokesman said delays to remaining flights on Monday were possible.
He said passengers should allow extra time for their journey to the airport.
'Short notice cancellations'
On the railways, First Great Western said a number of trains between south Wales and London Paddington had been cancelled.
"Poor weather conditions on the Weston-super-Mare to Bristol Parkway route has led to disruptions and short-notice cancellations and delays of up to 20 minutes," a spokesman added.
Bus operator First said most services in the Bristol area were running normally but some delays should be expected.
"All services in Weston-super-Mare have been cancelled including those travelling to and from Bristol," a spokesman said.
Ch Insp Polly King, from Avon and Somerset police, said: "The weather is making driving more hazardous at the moment and people should be very careful if they are setting out on the roads.
"Listen to travel bulletins on the radio and always take with you an emergency kit including warm clothes, food, water, boots, a torch and spade.
"Anyone venturing out should stick to major routes if possible and be wary of sat-navs suggesting routes which may include rural, untreated roads."
Gritting crews worked around the clock in north Somerset to keep roads clear after snow fell at the weekend.
About 5ins (13 cm) fell in Weston-super-Mare. Volunteers with 4x4s drove staff to the town's hospital.