The Royal Meteorological Institute (RMI) announced a yellow alert from midnight to 7am.
On Thursday evening clouds will begin to gather in many places. The minima will be between -5 degrees in Hautes-Fagnes, Wallonia, and -1 degrees elsewhere.
Towards the middle of the night, snow will arrive, in south as well as in the northern half of the territory.
A thin layer of snow is expected in Brussels.
On Saturday, the sky will often be very cloudy clearing out only for a few moments during the day.