Wales snow: 120 schools shut as freeze continues
Motorists are being warned of further possible travel disruption and around 120 schools are closed as the freezing weather continues.
An ice warning is in place for south Wales with many roads still treacherous and a chance of snow flurries.
A bus carrying 20 pupils slipped off a steep road covered in slush and snow at Abercarn in Caerphilly county.
The school closures are mostly in the south Wales valleys, with many others only partially open.
Temperatures overnight fell to -2C in parts of mid Wales and remained around freezing in much of the country.
While major routes are mostly open, some mountain and minor roads are still closed and many others around the country continue to be treacherous.
Areas with school closures include Rhondda Cynon Taf (RCT), Anglesey, Gwynedd, Blaenau Gwent, Caerphilly, Torfaen, Bridgend, Cardiff, Newport, Swansea, Powys and Merthyr Tydfil. RCT appears to be worst hit with at least 30 schools shut.
RCT council said secondary schools were being prioritised because some pupils were sitting exams this week.
Powys council said school transport would operate on Monday after being frozen out by snow on Friday.
A spokesperson said: "The council has looked at the weather forecast for the next 24 hours and, with the primary roads now clear of snow and ice, school transport and recycling and refuse collections will resume."
Other areas hit by school closures on Friday were advising parents to keep an eye on local authority websites and Twitter feeds for updates.
Caerphilly and Denbighshire councils said most schools planned to open, while Monmouthshire said all were expected to.
Many closures were related to health and safety reasons, with pavements and playgrounds still icy.
But parents and pupils helped to clear school playgrounds and pavements in some areas, with more than 50 turning up at Ysgol Gynradd Creigiau near Cardiff on Sunday.
In Caerphilly county, a bus carrying Abercarn Primary School pupils went off Llanfach Road, which was covered in slush and snow.
Nobody was injured in the incident which happened at 09:00 GMT on Monday.
Meanwhile, temperatures were expected to remain close to freezing around Wales and there was a risk of further localised snowfalls of 1-3cm.
There was a yellow "be aware" risk for ice in south Wales on Monday, and an ice warning for most of Wales on Tuesday.
South east Wales also has a snow warning for Tuesday, with a risk of travel disruption.
"The public should be aware of the risk of disruption to travel during this continuing spell of wintry weather," said the Met Office.
The Penderyn, Maerdy, Bwlch and Rhigos mountain roads in south Wales all remained closed on Monday afternoon, although the A542 Horseshoe Pass in Denbighshire has reopened.
Local authorities say they have been working hard trying to keep important routes open.
Caerphilly council said its gritting vehicles had covered a distance of more than 5,000 miles (8,047km) since Friday morning.
Its team had spread around 1,400 tonnes of salt worth £90,000, and the local authority said it was well placed to tackle further spells of cold weather with over 5,500 tonnes still in storage.
On the trains, there were delays of up to 30 minutes on First Great Western services between Cardiff Central and Bridgend due to signalling problems.
The problem is also affecting Arriva Trains Wales services.
The Royal Gwent Hospital in Newport and Abergavenny's Nevill Hall Hospital were busy with an increase in ice-related falls.
BBC Wales weather forecaster Behnaz Akhgar said there could be more snow during the day, and frost at night.
"You will need to take care especially on untreated surfaces in the south and there is a warning in force," she said.
"Through the day we could see the odd snow flurry, especially in the north, but we could also see some brightness and a few breaks in the cloud in the south.
"There could be highs of 3C and the winds will be lighter than they have been recently."
She said a severe frost would develop on Monday evening with further snow flurries possible overnight.