Back in Sweden as commanding officer of the Army Ranger School in Kiruna, he was responsible for the Swedish military's relationship with the Norwegian resistance and made major contributions to them through active support to the Norwegian bases on the Swedish side in what was called Operation Sepals.
After the war, Wetterhall eventually became commanding officer of Falun Defense District and worked as a ski competition administrator.
Wetterhall was promoted to underlöjtnant on 1 January 1928 and to lieutenant on 1 May 1929 and studied at the Royal Central Gymnastics Institute in 1930.
Back in Sweden, Wetterhall was promoted to major and was appointed as the first commanding officer of the Army Ranger School in Kiruna on 1 April 1944.
[2] He took an early retirement on 1 November 1955 and was at the same time placed in the reserve and promoted to colonel and appointed commander of Falun Defense District.
As a young man, he belonged to the elite of Swedish modern pentathlon and became military pistol champion in 1958.
[6] On 19 December 1934 he married gymnastics director and physiotherapist Barbro Emma Helena Hasselblad (13 January 1909 in Stockholm – 19 February 1990 in Falun), the daughter of the war councillor (krigsråd) at the Royal Swedish Army Materiel Administration Sven Åke Waldemar Hasselblad and Elsa (née Nordström).