Celebrity Summer Isn't Over Yet: See the Latest Hot Concert Looks! By Caitlin Petreycik Caitlin Petreycik Caitlin Petreycik is a writer and editor based in Brooklyn who covers all things food, fashion, design, and pop culture. In addition to InStyle, her work has been published in Glamour, Food & Wine, Vox, and New York Magazine. InStyle's editorial guidelines Published on September 26, 2011 @ 11:45AM Pin Share Tweet Email Photo: Ethan Miller/Getty Images Sure it’s already fall, but the latest performance outfits make us feel like it is summer concert season all over again!Jennifer Lopez was just one of the many celebrities who hit the stage over the weekend, dropping by the iHeartRadio Music Festival in Las Vegas to belt her dance-floor hit "On the Floor" in a red fringe mini, gold heels, and rhinestone-studded tights. Click through the gallery to see outfits worn by Rihanna, Lady Gaga, Carrie Underwood, and more. Tell us: Have you seen any good live shows lately? MORE:• Billboard Music Awards Red Carpet• MuchMusic Video Awards 2011• Billboard Music Awards Red Carpet