The Met Office has issued a new yellow warning for a large area between south and mid Wales on Wednesday evening.
The warning for snow lasts until 10am on Thursday with some higher roads in Wales expected to be affected the most.
It covers areas such as Lampeter, Merthyr Tydfil and Llanwrtyd Wells.
The Met Office said roads and rail lines in this area are likely to be affected by lying snow with longer journey times by road, bus and train.
There were reports of vehicles abandoned on Twyn Hill in Merthyr and in Ystradgynlais on Wednesday evening and police closed the road through the Brecon Beacons as snow started to stick.
A second yellow warning for rain is also in place for much of south Wales, as downpours are expected to move through the region from midnight, during Thursday and into Friday morning.
The Met Office has warned the heavy rain may bring some disruption through flooding.
The forecast for Thursday
Overnight through to Thursday, the rain will edge southwards leaving northern parts drier by dawn. The minimum temperature will be -1 °C.
Much of Wales can expect persistent rain throughout Thursday, with temperatures unlikely to exceed 6°C. By the afternoon, it will be brighter in the west but it will feel cold, especially in the wind.
The outlook for Friday to Sunday
Friday will be mostly cloudy with some blustery showers. Saturday and Sunday look to be brighter and drier days with the odd shower. It will remain cold throughout.
