Belgium is a popular tourist destination and continues to attract droves of tourists year round! The ideal time to visit the country would be between May and September as the summer is setting in. Boom receives its maximum traffic of visitors during the much awaited music festival Tomorrowland. The worst of the summer is over by the time July comes around. Temperatures cool down as the day goes by and during the day, it’s warm enough to enjoy Tomorrowland in just about any clothing you’re comfortable in.