The New York native is adamant playing outdoor gigs in scorching sunshine is boring, and he would much rather sing to thousands of fans in the middle of a downpour.
The band is due to play on the festival's main stage on Sunday (30Jun13) and Koenig is praying for a spot of bad weather over the site.
He tells British newspaper The Sun, "We've played twice before. When we played one time, it was so warm and sunny it threw me off. For us, we play Coachella and it's hot, so I like the cold U.K. summer vibe. When I picture Glastonbury it's grey and wet, there's something kind of cool about that, too."