Sunday will be changeable with sunny spells, scattered showers in the west and north-west, and temperatures of 19°C to 23°C, according to the Royal Meteorological Institute.
It may also be quite windy along the coast.
Overnight, a new band of showers will move across the country from France and the coast. Some of these showers may be thundery.
Minimum temperatures will range from 12°C to 16°C. Strong winds will persist by the sea.
Monday, the final day of the summer holidays, will also be unsettled. Showers in the afternoon may be accompanied locally by thunderstorms.
By late afternoon, conditions should turn mainly dry, with broader clear spells developing. Highs will range from 17°C in the Ardennes to 21°C in Flanders.
There may also be isolated strong gusts of up to 70 km/h.
Tuesday and Wednesday are expected to stay largely dry, with temperatures around 20°C to 21°C.
Rainier weather is forecast to return on Thursday.
