Performances at the Latitude Festival were suspended for about an hour after lightning and heavy rain caused the power to be turned off.
Organisers of the event at Henham Park, Suffolk, said performances were paused on the Obelisk Arena Stage, the BBC Sounds Stage and the Lake stage, as a precaution.
They were waiting for “inclement weather to pass” they said on Twitter.
“Lightning is the concern, not rain” it said after people complained of delays.
“We are currently still awaiting any lightning around the festival to pass before we can safely resume performances.
“Thank you for your patience during this time” it said.
The power was back on by about 14:50 BST.
Some festival goers on Twitter were unhappy. One said “Sitting under clear skies. This is a joke”.
Another and said: “How can a festival shut down for half an hour over less than 5 mins rain?”
“This is currently a music festival with no music” said another.
The event is now back up and running but Futureheads were unable to finish their set at the Obelisk Arena.
“All other set times on BBC Sound Stage will start a few minutes later than scheduled”, organisers said.
The festival started on Thursday and runs until Sunday and attracts about 40,000 people.
Acts on the bill include George Ezra, Stereophonics and Lana Del Rey and comedians Frank Skinner and Marcus Brigstocke.