The Met Office has issued a new warning for widespread ice and possible sleet across South Wales on Sunday night as driving conditions remain treacherous this morning.
Temperatures reached as low as minus 5 Celsius overnight and the big freeze is showing no signs of abating.
Most rail and bus services have returned to normal following disruption because of heavy snow but motorists are being urged to take care and travel only if necessary.
There is a warning of hazardous driving conditions because of snow and ice on the M4 near Bridgend, both ways between junctions 36 (A4061) and 38 (A48 Margam off-slip).
The Highways Agency says the M48 Severn Bridge, shut on Friday afternoon by 4in of ice which caused vehicles to spin out of control, will not open until at least 6am on Monday.
In addition, one lane remains closed in both directions on the M4 Second Severn Crossing.
Throughout the region, gritters have been out in force spreading tonnes of salt over the last 24 hours.
A Met Office yellow "be aware" alert of ice had already been issued for Sunday morning and a new one will be in force from midnight tonight until 12pm tomorrow.
It says: "Sub-zero overnight temperatures will lead to ice forming where snow has fallen or melted during Sunday or where fresh sleet or snow falls early on Monday.
"The public should be aware of the risk of disruption to travel during this spell of wintry weather."