The Met Office says Sennybridge in Powys was the coldest at a chilly -5.8C.
In Bala, Gwynedd, the temperature fell to -5.3C and at Usk to -5C.
South Wales Police published the following advice when driving in icy and snowy conditions.
- It says you must be able to see, so clear all snow and ice from all your windows.
- You must ensure that lights are clean and number plates are clearly visible and legible
- Keep well back from the road user in front as stopping distances can be ten times greater than on dry roads
- Take care when overtaking vehicles spreading salt or other de-icer, particularly if you are riding a motorcycle or cycle