The cold never bothered her anyway.

By Devan Coggan
Updated November 01, 2015 at 12:00 PM EST

Taylor Swift brought the U.S. leg of her 1989 Tour to a close Saturday night in Tampa, Fla., with a little Halloween spirit and — surprise! — a special guest, inviting Idina Menzel onstage for a performance of “Let It Go.”

After Swift welcomed Menzel to the stage, the two artists let the storm rage on in costume, with Menzel donning a sparkly Elsa dress and Swift becoming the snowman Olaf.

RELATED: See How Hollywood Does Halloween 2015

“Frozen totally happened tonight,” Swift wrote on Instagram. “And 55,000 people sang ‘Let It Go’ so loudly, it nearly took my breath away.”

But Elsa wasn’t the only surprise guest to take the stage in Tampa: Alessia Cara also performed her hit song “Here.” A few months ago, Cara covered Swift’s “Bad Blood” remix featuring Kendrick Lamar on BBC Radio 1 and impressed Swift herself, who tweeted that Cara’s cover was “AMAZING.”

“Thank you for showing me what 55,000 people looks like,” Cara wrote to Swift on Instagram after her performance last night. “You are the classiest, sweetest, most lovely person and I can’t thank you enough for what just happened. Also I can’t feel my body. Goodnight everyone I quit life.”