Summer months are great to visit Slovenia for outdoorsy activities, especially in the Soca Valley. But keep in mind city centres, Lake Bled boating and camping areas will be super crowded. Visiting in late August or September will allow you to enjoy stunning vistas, and a relaxed city break without the crowds. If you are into winter sports, plan to visit Slovenia in January. Winter activities include skiing, snowboarding, and snowshoeing in Triglav National Park, and nearby areas.