Clouds, sometimes accompanied by light drizzles, will accumulate from the north of Belgium on Sunday afternoon, according to the Royal Meteorological Institute (RMI).
There will be fewer chances of rain in the west and some patches of clear sky will still be possible along the French border.
Temperatures will remain cool for the season, ranging from 13 degrees in the Ardennes to 19 degrees in the centre, while the wind will be quite strong along the coast and at sea, and moderate elsewhere.
Some light rain and intermittent showers will still be possible on Sunday evening, but skies will gradually clear up overnight.
In the Ardennes, the weather will remain very cloudy, sometimes with light rainfall and fog along the heights. Minimum temperatures will be between 11 and 17 degrees. The wind will blow in from the north, generally moderate, but quite strong at sea.
On Monday, the skies will be sometimes cloudy, while a few showers will be possible. Maximum temperatures will range from 16 to 21 degrees.
Dry weather is to be expected from Tuesday, with highs topping 20 degrees.