Temperatures in Brussels are mild year-round, with the summer ranging between 54 and 72 degrees and winter a temperate 32 to 43 degrees. Light rains are possible any time of year, so carry an umbrella. The best time to visit Brussels is late spring to fall, as weather is perfect for walking and al fresco dining.
High season runs from May through July with a resurgence in September and October. Diminished crowds occur in the late August, when it’s fairly hot. Since 1549, Brussels has celebrated the Ommegang Festival on the first Thursday of July, in honor of Charles V and his son Phillip. Some 1,400 costumed revelers join a procession at the Place du Grand Sablon, watched by spectators and respected Belgium dignitaries including the Royal Family.
Shoulder season is mid-January to April, November, and early December, with manageable lines to attractions and reasonable prices. Average temperatures from March to May range from mid-30s to 60s. Winter months (December to February) are often grey and overcast, with temperatures averaging in the 40s.
Popular events celebrated in Brussels include: Brussels Antiques and Fine Art Fair (January); Carnival (February); Sablon Baroque Spring Festival (April); Zinneke Parade and Brussels Jazz Marathon (both May); Brussels Music Festival (June); European Film Festival (June/July); Brussels Summer Festival (August); Brussels Beer Weekend (September); Comic Strip Festival (October); and Brussels Christmas Market (December).