Sunday was hot, and any performance in the sunny open areas, no matter how good, was bound to be less enjoyable simply because of the oppressive heat. When Wisconsin’s Phox took the aptly named Forest Stage (a quiet corner spot in the shade), they recognized the blessing right away. More hydrated fans are more receptive fans, and Phox’s crowd couldn’t have been more cordial, allowing the band’s delicate, gorgeous folk-pop tunes they space they require to properly bloom. Singer Monica Martin’s voice evokes a sweetness every time she twists a phrase, but the harmonies from bandmates Matteo Roberts and Jason Krunnfusz add another dimension of color to everything she conveys. So when the instruments dropped out and the three locked in place for a three-part a cappella indulgence — in the cool, breezy shade, remember — it felt downright heavensent. Then, a sincere cover of Blink-182’s “I Miss You” and their very own mini-hit “Slow Motion,” and they graciously exited. Thanks for the brief getaway, Phox, even though it couldn’t last forever.