'Bitterly cold' overnight in Wales warn forecasters
Bitterly cold weather conditions are forecast for Wales overnight as the big freeze continues.
The Met Office has warned of icy patches on untreated roads, particularly where snow freezes.
Overnight temperatures of -3C (26.6F) are expected in Cardiff and Swansea and -8C to -10C (17.6F to 14F) for towns in Gwynedd and Conwy.
Meanwhile, flu sufferers are urged not to attend A&E departments unless absolutely necessary.
Public Health Wales said unless people's symptoms are very severe, they are pregnant or in an at-risk group, they can treat themselves at home without needing to visit emergency rooms that are already busy due to the weather.
Dr Marion Lyons of Public Health Wales, said: "Although flu is unpleasant, it usually resolves itself within a week and it is not advised that patients visit their GP surgery or A&E department.
"This only risks spreading the infection to others, and it is unlikely that any medication will be prescribed in most cases."
Travellers have faced treacherous conditions with snow and ice in many parts of Wales.
Cardiff Airport was closed between 1700 and 1900 GMT to clear the runway.
Passengers were advised to contact their airline or tour operator for further information about specific flights before travelling to the airport.
Drivers experienced very slow traffic and hazardous driving conditions on the M4 in both directions at Cardiff and Newport.
Train services have also been disrupted.
Arriva Trains services on the Cardiff and Valleys lines were temporarily suspended but trains resumed in the afternoon, apart from the Coryton-Radyr City line.
First Great Western also said many of its services were being disrupted and cancelled, including Cardiff to London and routes between Wales and the west country.
Bus services in Swansea, the Swansea Valley, Neath and Port Talbot stopped after 1830 GMT.
Veolia Transport suspended all services in the Pontypridd, Cardiff, Caerphilly and Bridgend areas until further notice and in Carmarthenshire and Neath Port Talbot bus services were also affected by the snow.
The Wales Ambulance Service earlier warned of potential "long delays" in responding to 999 calls and asked people to only contact 999 if "absolutely necessary".
Up to 10cm (4in) of snow fell in south and west Wales on Monday with up to 14cm (nearly 6in) on higher ground in middle Wales.
Temperatures fell as low as -17C (1.3F) at Capel Curig in Snowdonia overnight on Sunday.
Police have warned drivers to clear all snow and ice from their windscreens and car roofs fully so snow does not slip and obscure their vision.
Drivers who ignore this warning could be prosecuted, the South Wales and Dyfed-Powys forces have warned.
The main A48(M) reopened in Cardiff after a fuel tanker fire on Sunday.
Meanwhile, an air ambulance crew condemned youths who pelted their helicopter with snowballs as they tried to land in Swansea on an emergency call.
The ambulance service said the weather had brought difficulties in maintaining its normal service for routine patient transport.
A spokesman said it would concentrate on patients identified by health boards as being at clinical risk, such as renal and cancer patients.
Household bin collections are currently suspended in many counties with Bridgend cancelling all its collections this week, up to and including Christmas Eve.
The Royal Mail said it had been unable to deliver to some houses in Ceredigion for four days and is now asking the public to collect their mail from their local sorting office.
Deputy First Minister Ieuan Wyn Jones, on a visit to the North Wales traffic control centre at Conwy, said: "The present arctic weather is testing the capacity of our services to the limit
"We all owe a great debt of gratitude to the men and women in our police, emergency and traffic services for their round the clock dedication."