Mittenwald has two clear seasons. June to September is hiking season — long days, alpine flowers, and reasonable weather for the high routes, though afternoon thunderstorms are common. December to March is the ski season; the town is small but the area is well connected to Garmisch and the Austrian resorts. The shoulder months of April-May and October-November can be quiet and grey, with many cable cars on maintenance closures.
For the warmest, most settled summer weather, aim for July or early September. The town has a strong tradition of brass band music in summer — concerts most evenings in the bandstand on Obermarkt. The Karwendelfest in early August brings folk music, parades, and the costumed crowning of a "Karwendel-Schnitterin" young woman.