Apparently, there's nothing like a severe weather evacuation to get the party started at the Summer Set Music & Camping Festival — just one of Sunday's many signs that there's nothing like Summer Set, period.

The fourth annual, peculiarly psychedelic grooveathon — think: giant dance rave meets head-shop tent sale meets river tubing — got off to something of a languid, ragged start on its third day, which was to be its biggest day yet with its biggest dance DJ yet, Deadmau5.

Fans appeared listless at first after spending the first two days of the fest baking in the hot sun at Somerset Amphitheater in Somerset, Wis. And yes, "baking" is meant to be a double entendre.

Eyeing the many audience members sprawled out messily on the dusty grass around The Grove stage, Merrill Garbus of New York's trendy sonic-collage band Tune-Yards remarked, "We're here to play for you, if you still have some party left in you."

As the 6 p.m. mark neared, though — just minutes after the horror-schticky South African techno rap duo Die Antwoord took the main stage (already a disturbing experience) — the slow-going party came to an abrupt halt as organizers took over the microphones and told the 20,000 or so fans they had to evacuate the premises and seek shelter.

The news was as weird as everything else at Summer Set since: a) there wasn't any shelter in sight, and b) there weren't any dark clouds or thunder around, either, just a light trickle of rain. All of a sudden, the music fest that lets fans ride a real Ferris wheel on site despite an obvious lack of coherence was being overcautious with safety.

Aside from some fans' disappointment that Die Antwoord and G-Eazy both had their sets cut — personally, I'd say it worked out great — the hour-long weather scare-that-wasn't-very-scary somehow sparked the party back to life.

Over at the The Grove stage where Tune-Yards had played pre-evacuation, the grounds were swarming with haggard but hyperactive bodies grooving heartily to Toronto electronic duo Zed's Dead. Between the flaming pyrotechnics on stage and the many oddly costumed fans in the crowd, it looked like a mob scene in the latest "Mad Max" movie — although ZD's formulaic, booming, dubstep-flavored dance jams sounded more like a "Grand Theft Auto" video game soundtrack.

Hardly just an electronic dance fest, Summer Set's true, prism-like colors also finally shone through soon after the evacuation as the festival's odd array of psychedelic stage lighting turned on, and the genres among the stages became as mixed up as the kids getting off that Ferris wheel.

One stage over from The Grove at The Meadow, the rapid-grinding dance music was sharply contrasted by the hard-picking fiddle and mandolin solos offered up by rootsy New Jersey jam band Railroad Earth. Man, can those boys play. And play. And play.

Over on the main stage bellowed Action Bronson, a beefy, imposing New York rapper who might have been mistaken for Deadmau5's body guard instead of his opening act. Bronson hit the crowd hard with his abrasive and often riotous lyrics in such songs as his Mick Ronson-produced romp "Baby Blue" ("The thought of me succeeding makes some people nauseous / Still I'm on the back of the boat taking pictures with swordfish").

An even better, lesser-known rapper, F. Stokes, performed soon after Bronson just up the hill in the amphitheater's permanent saloon (named The Saloon). The Chicago native wasn't content with the venue's barn-vibe stage, so he climbed out into the crowd and had fans chant along face-to-face during his "Shaka Zulu."

When the time finally came for Deadmau5 — right on time, surprisingly — the crowds all came together around the main stage as one bulging, constantly bobbing mass. The mouse-headed Canadian DJ started off performing inside an elaborate dome-shaped lighting structure that split off into different pieces as his set whirred on. He also took off his big-eared helmet mask mid-set and revealed the real Deadmau5 (Joel Zimmerman, 34), which proved as anticlimactic as the set itself.

The mouse man started off strong with harder-pumping fan faves such as "Ghosts N' Stuff," but he actually slowed his tempos and turned more ambient in the second half leading into "Silent Picture." It got mellow enough that fans clearly were waiting for the music to snap back when — after only 80 minutes — the sound and lights turned off, and an announcer took the stage again to alert fans the party was over.

Too bad the second abrupt ending of the day wasn't another false alarm.

Quick quotes from Sunday's Summer Set sets

"I'm about to take Molly for the first time and I'm a little nervous." — Philadelphia yuckster rapper Lil Dicky, as he ended his opening set on the main stage, referring to a drug known to be popular at dance music shows. He was probably kidding.

"Here, pass that back." — Action Bronson, handing what he said was a lit joint to a flummoxed-looking woman security guard standing between him and the audience. He wasn't kidding, and she actually did as told.

"He almost sounds in tune with us." — Merrill Garbus, referring to the beeping sound of a truck backing up near the stage where her band Tune-Yards was playing similarly staccato, beep-like sounds.

"Isn't life great?" — Singer/guitarist Adam Greuel, stopping to enjoy the warm reception on The Meadow stage for his Stevens Point, Wis.-reared acoustic/bluegrass band Horseshoes & Hand Grenades.

"..." — Deadmau5, who did not say a word to the crowd, keeping in character.

Twitter: @ChrisRstrib • 612-673-4658