The program featured music by Mozart, Schumann, and Shostakovich in honor of the 250th anniversary of Mozart's birth, the 125th anniversary of Schumann's death, and the 100th anniversary of Shostakovich's birth.
According to ORF, organizers were concerned that the rain would damage the instruments of the Philharmonic musicians, despite the roof over the stage.
The organizers are attempting to find a new date for the concert, preferably before Austria gives up the rotating presidency of the European Union on July 1.