[1] Weimann was one of the world's top javelin throwers by 1930, when he threw 66.97 m.[2][3] He placed third behind two Finns at that year's International University Games in Darmstadt with 64.24.

[4] Ahead of the 1932 Summer Olympics in Los Angeles he threw 69.54 in Leipzig[3] and entered the Olympics as the main challenger to Finland's javelin supremacy, as the other top non-Finnish thrower, Estonia's Gustav Sule, was not competing.

[2][5] Weimann won another bronze medal at the International University Games in Turin in 1933, missing out to Hungary's József Várszegi and Sule.

[4] Later that year he reached his eventual personal best, 73.40, in Gdańsk;[3][6] at the time, that distance placed him second in the world, behind only Järvinen.

[6] He placed sixth at the inaugural European Championships in 1934[1] and remained in shape for another two years, throwing 72.24 in July 1936,[3] but at the 1936 Olympics in Berlin he only managed 63.58 and placed ninth.