Donaueschingen sits at around 700 metres in the Schwarzwald-Baar plateau and gets proper continental weather: warm summers, cold winters, and frequent snowfall from December to March.
May to September is the best stretch for visiting — the palace grounds are at their prettiest, beer gardens are open, and the Danube cycle path is comfortable. The Donaueschinger Musiktage, one of the world's most respected festivals of contemporary classical music, takes place over a long weekend in mid- to late October. If avant-garde composition is your thing, that is the time to come; book accommodation well ahead. Otherwise the town is quiet in winter, with little open and shorter daylight hours.