For six hours every autumn, the hip-hop cosmos temporarily spins around the emerald quadrangle of Howard University during the annual Yardfest homecoming concert, a rap saturnalia that’s been immortalized in a Notorious B.I.G. lyric.

But this cosmic realignment might soon become a twice-a-year thing for Washingtonians with the gathering momentum of Trillectro, the hip-hop and dance music festival that celebrated its third annual go-round on the asphalt plains outside RFK Stadium on Saturday.

The line-up wasn’t as starry as your typical Yardfest, but this year’s Trillectro did a better job of capturing contemporary hip-hop’s riotous spirit. And it culminated with a surprise performance from Travis Scott, an irrepressible Houston rapper who obliterated the demarcation line between artist and audience, inviting front-row fans to leap over the barricades while flinging his body out toward the masses.

Prior to that, the biggest sonic thrills came bouncing off the tongues of the young Atlanta trio Migos. During the verbal stampede of “Handsome and Wealthy,” the trio pondered their own appeal: “Is it my looks? Or is it my wealth? Or is it the way that I carry myself?” Rhetorical questions, maybe, but it probably had do with their ability to dress loud and rap louder.

These energy spasms were welcome and necessary after heavy rains spoiled the first half of the day-long festival. Washington’s own Diamond District — a trio that includes Uptown XO, Oddisee and yU — gave the afternoon’s most valiant performance as a stagehand squeegeed gallons of water off the lip of the stage.

Takeoff and Offset of Atlanta rap trio Migos perform at the 3rd annual Trillectro Music Festival at RFK Stadium in Washington, D.C. The group is known for their singles "Versace" and "Hannah Montana." (Kyle Gustafson/For The Washington Post)

They were among a bevy of local rappers invited to the Trillectro stage this year, including Lightshow, Ras Nebyu, Tabi Bonney, Goldlink and a shirtless Fat Trel, who tempered his usual relentless nihilism with words of kindness for Michael Brown and words of fury for the police.

It was heartening to see this festival grow without losing its homegrown spirit. Founded and organized by three area natives, Trillectro has its roots in the rap blog DCtoBC, and its organizers seem committed to showcasing Washington talent while expanding the festival’s scope.

But growing up begets growing pains. Last year’s Trillectro took place at the Fairgrounds outside Nationals Park, which made for a very tight squeeze and some incredible energy. This year outside RFK, there was a lot more space for fans to roam, increasing comfort but diluting the day’s intensity.

Also, the biggest names kinda whiffed. Big Sean, a Detroit rapper whose inconsistent body of work is garnished with flashes of greatness, was flashy and only almost great. His co-headliner, Baauer, producer of the infamous “Harlem Shake,” delivered a DJ set so sodden with rap hits it failed to differentiate itself from the transitional music being pumped over the speakers between performances. (If the DJs are going play rap almost exclusively, why not just book more rappers?)

There was a fantastic dab of R&B, though, and it came around dusk from the 23-year-old SZA, who presented her slow-moving songs with an adept live band and an unhurried charisma. “Show me the way to your hiding place,” she demanded on “Ice Moon Revisited,” clearly in no rush to get there. She sang like syrup refusing to dribble from the bottle.

SZA was followed by a whiplashing appearance from Rae Sremmurd, a teenage Mississippi duo who climbed the speakers and rode skateboards across the stage before spitting out their rowdy summer hit, “No Flex Zone.” But the duo’s unreleased tunes — including the forthcoming single “No Type” — proved they have enough melodic smarts to graduate them from one-hit-wonderland to adulthood.

Rae Sremmurd — and the festival that brought them here — were growing up before our very eyes.