Brussels in December

April through September offers the best weather, but Brussels works year-round. May and June are perfect — mild temperatures, longer days, and the city's parks come alive. July and August bring crowds but also outdoor festivals like Brussels Summer Festival in Parc Osseghems. September has ideal weather and fewer tourists. Winter gets dark early and rains constantly, but Christmas markets around Grand Place create magic from late November through January. Spring arrives late — March still feels like winter. Book accommodations early for EU summit weeks when hotel prices triple.