Motorists are being warned to make journeys only if necessary and to take precautions against a breakdown or delays as snow continues to fall.
More than 270 schools are closed across Wales, mainly in the south, compared to more than 600 shut on Thursday.
There has been more snow overnight with up to four inches falling near Brecon in Powys.
The A470 is shut between Merthyr and Brecon and the M4 between Junctions 22 and 25 is described as "hazardous".
One lane is closed in both directions on that stretch of the motorway and a 30mph speed limit is in place. The A4061 at Treorchy and Hirwaun is also closed as is the A4067 Sennybridge to Ystradgynlais road. Police said the A465 Heads of the Valley Road is "just passable" in both directions between A469 (Rhymney) and A4060 (Dowlais Roundabout).
Comment