Amsterdam is worth visiting year-round, but the calculus is simple: July and August are peak tourist season, when prices are highest, queues are longest and the Anne Frank House requires booking weeks ahead. May and June offer long days, tulip season in the wider region, and fewer crowds. September is excellent — warm enough, the summer masses have gone. Winter is grey and wet but the canals are atmospheric and the museums are emptier. King's Day (27 April) turns the city into an enormous orange street party and is either a highlight or a reason to stay away, depending on your tolerance for crowds.