When Thanh and I planned an outing to Brussels for the Senne Park, the Pannenhuis Park also known as L28 Park and the Maritime Station, the weather forecast announced snow (!), then rain but in the end the weather gods were clement and it was dry and sometime sunny. The date was 11 April 2021.
What about the Belgian Pride in Brussels in May 2021? Organizer The Belgian Pride (with article) remains tight-lipped on the subject. But it is mobilising businesses, corporations, non-governmental organisations, institutions et al. to fly the rainbow flag in May. That project is called RainbowCity.Brussels.