Amber warnings are more serious than yellow warnings and indicate a possible risk to life, as well as more significant travel disruption.
Photographs show snow settling on the ground in a number of places around the country on Saturday evening.
Areas include many parts of Wales along with western, central and southern counties in England including Gloucestershire, Wiltshire, Hampshire, Surrey and Oxfordshire.
Bristol airport halted flights for a period of Friday evening. Operations restarted around around 23:00 GMT but passengers were warned there could be ongoing delays on Sunday and to check with their airline before traveling.
Wiltshire Police said the weather was “causing chaos” all over the county, while Avon and Somerset Police warned of significant road disruption. Both forces advised only to travel if necessary.
The National Grid said there were a number of power cuts and they were working to restore power to some properties, including in Birmingham, Bristol and Cardiff.