Predictions of thunderstorms and an ominously black sky weren't enough to deter more than 4000 people from braving the soggy slopes of the National Arboretum for Voices in the Forest on Sunday.
But less than two hours into the fourth annual concert the wet weather gear organisers urged the crowd to bring came in handy when the rain began.
Concert-goers scrambled to take shelter when organisers "paused" the concert to wait out the storm.
But as rain and thunder continued, close to half chose to leave on the free buses that ferried the crowd out to the event from the city.
The concert resumed for the finale after about 45 minutes.
While some concert-goers took to social media to criticise organisers for going ahead with the event despite the weather forecasts, organisers defended the decision saying they had several contingency plans.
"At no point was any member of the public at risk at the event," a spokeswoman for the organisers said.
"There was thunder and lightning, but it was not within the vicinity of the event it was much further away."
The spokeswoman said relocating the event was considered, but event organisers "were in close contact" with the Bureau of Meteorology.
"[The BOM] forecast showers of between four and five millimetres and that's consistent with what happened," she said.
"We were prepared for light showers with over 3000 ponchos."