May is the optimal time, coinciding with the Doudou Festival - Belgium's oldest carnival celebration. Summer months (June-August) offer warm weather, outdoor activities, and longer daylight hours perfect for sightseeing. Spring (April-May) brings blooming flowers and pleasant temperatures. Autumn (September-October) provides comfortable weather with fewer crowds and vibrant foliage. Winter (December-February) sees minimal tourism, making it ideal for budget travelers, though many attractions maintain reduced hours. Average temperatures range from 3°C in winter to 20°C in summer.