The Met Office said rain moving east across the region from late Thursday morning into the afternoon is likely to turn into snowfall in places.
Five centimetres of snow is forecast on ground above 200m and up to three centimetres could lie at low levels.
The yellow warning remains active until 6pm.
"The public should be aware of possible disruption to travel," the Met Office said.
Roads Service gritters have been salting main routes.
"Icy conditions are forecast," their Winter Service update read.
"Salting was carried out last night on all of the scheduled network. Further salting is underway this morning in some areas and is expected to be completed by 7.30am."
A blanket of snow fell across NI on Tuesday morning, followed by strong gales.
Dozens of schools were closed and dangerous driving conditions were reported.