Weissenberger, the son of a plant nursery owner, was born on 21 December 1914 in Mühlheim am Main in the Grand Duchy of Hesse of the German Empire.[1] He had a brother Otto who also served as a pilot in Luftwaffe.[2][Note 1] As a glider pilot with the German Air Sports Association (Deutscher Luftsportverband), he made his maiden flight on 16 November 1935.