7 . . . 6 . . . 5 . . . 4 . . . 3 . . . Was that the city ringing in the New Year, or the temperature winding down?

Bostonians welcomed 2018 with the city’s annual First Night celebration Sunday — admiring ice sculptures, enjoying musical performances, and anticipating the midnight fireworks over Boston Harbor — though the bitter cold led to the cancellation of some events.

It was a New Year’s Eve without the traditional evening parade to Boston Common followed by fireworks over the park, but that didn’t mean revelers weren’t enjoying themselves.

Inside Boston Public Library’s central branch, toddler Hazel Woo swayed in imitation of her grandmother, Grace Woo, who danced fluidly in a multicolored costume that evoked a butterfly.

They were surrounded by other families enjoying an instrumental performance and classical folk dancing, hosted by the Greater Boston Chinese Cultural Association.

Hazel’s parents, Kevin Woo, 34, and Christina Woo, 33, of Newton, said they hadn’t been to First Night in a decade.

“We came out to see the sights, now that we have a 2-year-old,’’ Christina Woo said, explaining that the family appreciated the celebration’s kid-friendly events — and stuck to those that took place indoors.

The celebration was more challenging for musicians playing outside in Copley Square. Guitar players struggled to strum with fingers that felt frozen. A trombonist’s slide kept seizing up.

After struggling through a performance of “Sing, Sing, Sing (With a Swing)’’ on the outdoor stage, the Downtown Boston Brass Band moved into a trailer to perform.

“If you’re wondering where the music’s coming from, we’re in the trailer,’’ trumpet player Joe Brogan told the bemused crowd.

“The instruments are just not working quite well today,’’ said Mike Testa, a promoter for First Night. “I think we still have an audience, Joe. What do you think?’’

Muffled applause could be heard through the walls.

Mayor Martin J. Walsh took the stage in Copley Square at about 6 p.m. to speak to a small but resilient crowd.

“We know who the toughest people in Boston are,’’ Walsh said. “They’re right here in Copley Square.’’

The cold also caused the cancellation of an ice skating show that had been planned for the Frog Pond in Boston Common, as well as most of the festivities on Monday, when temperatures are expected to reach a high of 10 degrees and a low of 3.

On Sunday morning, few skaters circled the Frog Pond — even as the sun shined brilliantly and the Common was covered in shimmering white. The hardy few who braved the cold said it wasn’t getting to them.

“I love it,’’ said Darren Holdway, 43, who was visiting Boston from Perth, Australia.

“Yeah, it’s good,’’ said his wife, Kelly Holdway, 39. “It’s our first time seeing snow, so to see it and feel it is wonderful.’’

Their visit also marked their inaugural attempt at ice skating — haltingly so, as they mostly clung to the outer rail while their children, 15-year-old Liam and 12-year-old Sienna, urged them on.

“It’s 100 degrees where we’re from, at the moment,’’ Darren Holdway said. “Barbecue and beach weather.’’

Sara Deiso, 36, and Jessica Hufnagel, 31, best friends from Bellingham, were both surprised by the small crowd. Their sons, 7-year-old Carl Peskin and 6-year-old Brandon Hufnagel, were fighting with toy lightsabers in front of the main stage, where they said they usually have to push through a crowd for a clear view.

The boys were upset that they couldn’t see the fire trucks in the parade, Deiso said.

“I wish they had done it earlier,’’ Hufnagel said of the city’s decision to cancel some key events. “I took off work, and I probably wouldn’t have done it if I knew.’’

Julia Sammy, 28, was so unperturbed by the cold that she was wearing a skirt with stockings.

“Honestly, right now, it’s not so bad,’’ she said. “But obviously, this would not be my outfit of choice.’’

Sammy explained that she lives in Toronto — where the temperature was about minus-1, according to the Canadian weather service — and she was on a layover in Boston.

Boston’s high on Sunday was 13 degrees at 3 p.m., according to the National Weather Service. By midnight, the temperature was expected to plunge to 4 degrees, with a wind chill of about minus 14.

That’s far lower than the 30-year average for New Year’s Eve in the area, which is a comparatively balmy 24 degrees, according to the weather service.

Terry McCullough, 55, of Plainville, and Annemarie Fitzgerald, of Barre, decided Sunday was a nice day for a walk, despite the temperature. They spent an hour strolling the city before making their way to Copley Square to check out the First Night events.

“We picked a cold day,’’ McCullough said. “It’s fun to see these ice sculptures with less of a crowd.’’

The single-digit temperatures also didn’t stop Emily Kearns and Henry Yoshimura, a married couple of 20 years from Andover, from their decades-long tradition of taking in First Night festivities, though they were disheartened by the cancellations.

“We are so frustrated. We are pumped,’’ said Kearns, bundled up in Copley Square just after the mayor spoke. “This is Boston. We can compete with the Minnesotans. This is nothing.’’

They said they couldn’t remember a New Year’s Eve as cold as this one.

Globe correspondent Adam Sennott contributed to this report. Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox.