Headline act Hello Sailor pulled out of The Fallen gig at War Memorial Hall after the Saturday concert was moved inside.
Wanganui man Iain Hyndman, who went to the gig, said concert attendance was "way, way down on expected". The area was able to hold 1300 people, but Mr Hyndman thought they would have been "lucky" to have 200 people when he showed up.
He was told it was "pretty much the same" throughout the concert.
"Nothing wrong with the performances at all," he said.
The Saturday gig featured other headline act Mi-Sex, as well as Ash Graham from Wellington plus Wanganui acts L40, Sin City, Greenfloor, My Damned Kind, The Black Trio and The Wicca Bees.
The concert was moved indoors because of unresolved noise control issues and the switch meant the budget could not stretch to two headline acts.