She changes back to her Summer attire on the 25th of February. In New Leaf, Isabelle changes her clothes from Summer attire to Winter attire in the second-half of October, specifically on the 17th of October. Isabelle talking about cardboard boxes. Isabelle in general may be a somewhat messy person, as Digby, who claims to be a neat freak, notes that while she isn’t too messy, it’s enough to get on his nerves.