The rain stopped, the sun came out, and it got crazy hot and sweaty on Randalls Island yesterday for the opener to the eight annual Governors Ball music festival. In other words, for tens of thousands of concert-goers, it felt like a muggy New York City summer day.

The long day of music, food, booze, dancing, and recovery naps began a little after noon with Lou the Human and Slaves, and ended some eleven hours later with headliners James Blake and Jack White saying good night to their respective fans at opposite ends of the sprawling festival grounds. Those last two had the largest crowds of the day, but one of the great things about events like Gov Ball is that seemingly every one of the 23 acts had its share of devoted supporters.

The Australian electronic duo Flight Facilities, the Palestinian rapper Belly, the Atlanta rapper 6lack, the Canadian pop-indie act Alvvays, the Maryland sing-songwriter Maggie Rogers: all had sizeable contingents of fans who gleefully sang out every word of every song. For 19-year-old Shawn Mendes, audience participation leaned more toward shrieking, as thousands of teenagers completely lost their shit in his presence. And Damian Gong Marley threw a terrific party at one of the more intimate-feeling venues, the "Bacardi Stage."

But it was Karen O and the Yeah Yeah Yeahs who really got the main stage area rocking yesterday, playing an exuberant, 75-minute set filled with hits from their seminal, NYC-sound records of the aughts.

If you're going this weekend, here are some tips.