[1] Fernström was born in Yichang, China, where he also spent most part of the first ten years of his life at the mission his father directed, except for a couple of years in Sweden.
He resided permanently in the Swedish province of Skåne from 1907 and started to study the violin at the conservatory in Malmö.
He was with the symphony orchestra of Helsingborg from 1916 until 1932, with some interruptions for studies; first as a violinist, later as one of its leading conductors.
Later the same year Fernström left the choir when he was appointed director of the municipal music school in the city of Lund.
In 1953, he was elected member of the Royal Swedish Academy of Music.