Vehicles have been stranded and some roads left impassable after snow fell across parts of mid and south Wales.
A Met Office yellow weather warning for snow for 11 of Wales’ 22 counties is in effect until 10:00 GMT.
A second warning for rain covers 13 counties and is in place until 23:45.
Traffic analysts Inrix said stranded vehicles and heavy snowfall meant some roads in Powys, Ceredigion and Neath Port Talbot were impassable. No school closures have been reported yet.
Inrix said snow was completely covering all the lanes on the A465 Heads of the Valleys road between the Glynneath interchange and Cefn Coed roundabout in Neath Port Talbot.
It warned of hazardous driving conditions and said drivers should approach with care.
Vehicles are stranded along the A4109 between Seven Sisters and Banwen in Neath Port Talbot and the road is impassable.
Falling snow caused disruption and blocked roads on Wednesday evening, with police in Ystradgynlais describing conditions as “treacherous”.
They said on Twitter people should “only go out if absolutely necessary”.
The A482 in Lampeter, Ceredigion, has been left partially blocked by snow and stranded vehicles and the A4221 between Abercrave and Coelbren in Powys is also impassable following heavy snow.
The weather warning for snow covers Blaenau Gwent, Caerphilly, Carmarthenshire, Ceredigion, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Powys, Rhondda Cynon Taff, Swansea and Torfaen.
The rain warning is in place in Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Newport, Powys, Rhondda Cynon Taff, Swansea, Torfaen and Vale of Glamorgan.
On Wednesday, a multi-vehicle accident and snow forced road agencies to close a 12 mile (19km) stretch of the A470 between Merthyr Tydfil and Libanus in Powys in both directions.
South Wales Police said it was “receiving a high number of calls about weather-related incidents” and advised people to allow extra time if travelling.
BBC Wales weatherman Derek Brockway said conditions meant Wales was experiencing “heavy rain, sleet and snow”.