Snow's been falling for most of the night in parts of south-east Wales, and the Met Office says there's more to come.
An amber 'be prepared' warning will remain in place until 9am, with a yellow warning of ice across the whole country.
Cardiff and Vale University Health Board has cancelled the majority of outpatient appointments.
David Wood reports from Porth, in the Rhondda.
More top news
Gravitational waves were predicted by Einstein but have never been spotted. Welsh physicists are modelling their astronomical sources.
Fly-half Dan Biggar remains on the road to recovery ahead of Wales' Six Nations clash against Scotland this weekend.
Manufacturers and unions have accused ministers of failing to protect the steel industry from cheap Chinese imports.