Weiß transferred to the Luftwaffe on 1 October 1934 holding the rank of Oberleutnant where he initially served as a technical officer with a reconnaissance squadron.

From October 1936 to July 1938, now a Hauptmann (Captain), he served on the Stab of Jagdgeschwader 134 "Horst Wessel" (JG 134—134th Fighter Wing).

[Note 2] In July 1938 he was appointed Staffelkapitän (Squadron Commander) of the Fliegergruppe 40 (40th Flyers Group) which was later renamed to II.

A German reconnaissance aircraft, a Heinkel He 46, had spotted a French armoured column of 50 tanks supported by 150 trucks and infantry on the advance.

[5] Following the conversion to the Messerschmitt Bf 109 at Braunschweig-Waggum, the Gruppe was tasked to attack various targets in Southern England during the Battle of Britain.

With the start of Operation Barbarossa, the German invasion of the Soviet Union in June 1941, the Gruppe, consisting of three squadrons Bf 109 and one Hs 123, was again subordinated to the VIII.

Weiß was promoted to Oberst (Colonel) on 1 November 1943 and served in the staff of Luftflotte 6 (Air Fleet 6) until the end of World War II.