Schwerin is a year-round destination, but May through September is when the city looks its best. The castle gardens bloom in spring, the lakeside promenades fill up in summer, and the light across the Schweriner See in the long northern evenings is exceptional. The Schlossfestspiele — the castle festival — takes place in the castle courtyard every July, staging opera and theatre with the fairy-tale turrets as backdrop. It is worth timing a visit around.
Autumn brings golden colour to the lakeside forests without the summer crowds. Winter is mild by German standards, and the Christmas market on the Marktplatz is small but atmospheric. Avoid coming solely for the castle in February or March — the interior museum has limited hours in the off-season.