When is Firefly Music Festival? October 21, 2019 16:07 Updated Firefly Music Festival will be held June 18th-21st, 2020! Check out fireflyfestival.com for more information--see you at The Woodlands! Related articles Where is Firefly Music Festival? Why did you go back to 4 days? Is Firefly for all ages? Does my festival pass include camping? When will the lineup be released? Comments 0 comments Article is closed for comments.