Nordmann was born on 22 November 1915 in Giessen, at the time in the Grand Duchy of Hesse of the German Empire. He was the son of a doctor and joined the military service of the Luftwaffe on 6 April 1936 as a Fahnenjunker (officer cadet). Nordmann was promoted to Leutnant (Second Lieutenant) on 1 January 1938 and served with 1.