His short-lived career was defined by a surprise win at the 1958 European Athletics Championships in a Swedish record of 2.12 m (6 ft 11+1⁄4 in).

In 1957 Dahl won his first significant medal, a silver at the national championships behind Stig Pettersson, the leading Swedish jumper of the era.

[4] He became the fourth, and thus the latest male Swede to win the title, following Kurt Lundqvist, Anton Bolinder and Bengt Nilsson.

[5] For this performance he was awarded the Svenska Dagbladet Gold Medal and designated the Stora grabbars märke number 200 in athletics.

After retiring from competition, he became a sports journalist for the local paper Länstidningen Södertälje, and later for the regional Nordvästra Skånes Tidningar.