The best months to visit Belgium are September and May. See monthly temperatures, rainfall and rain days (1991–2020 averages) to plan your trip.
Average daytime high and monthly rainfall in Belgium: January 6°C / 63mm; February 11°C / 59mm; March 12°C / 57mm; April 14°C / 47mm; May 19°C / 63mm; June 20°C / 66mm; July 22°C / 71mm; August 24°C / 71mm; September 20°C / 55mm; October 16°C / 59mm; November 10°C / 64mm; December 8°C / 74mm.