In the evening and at the beginning of the night, the sky will remain calm but gradually, more low clouds will drift from the northeast. In the second part of the night, (freezing) fog may form, mainly on the northern flank of the Ardennes, i.e. the provinces of Namur and Liège. Visibility may be limited to less than 200 m and frost patches may also form very locally.
On the southern flank of the Ardennes, in Belgian Lorraine and probably at the sea, the sky should however remain practically clear. The minima will be between -6 degrees in certain Ardennes valleys, or even locally a little less, and +2 at sea, with values close to 0 or -1 degree in the center of the country. The wind will generally become weak from north to northeast. At sea it will still be temporarily strong enough.
Tomorrow will start the day with patches of freezing fog and lots of low cloud. However, in the south-east of the country, the sun will be present. Then, clearings are expected everywhere but in Flanders, the clouds will be more present. The maximum will be between 2 or 3 degrees on the peaks of the Ardennes and 7 degrees in the center, even up to 9 degrees in Belgian Lorraine. The wind will be moderate from the northeast, gradually moving north.
Friday evening, the sky will initially be partly cloudy with occasional clear spells. During the night from Friday to Saturday, the cloudiness will increase from the north, the sky then becoming very cloudy to overcast with towards dawn, a risk of drizzle in Flanders. In the Ardennes, freezing fog may form again. The minima will be between -3 degrees on the relief of the Ardennes and +5 degrees at sea. The wind will generally be light from north to northwest. At sea, it will be rather moderate from the north.