Frenchman Matias Roche produced the best score of the night with a 95.25 on his first attempt but couldn’t back it up again, finishing in sixth.
Harrington is the third New Zealander to book a spot in a final today, after snowboarders Dane Menzies and Zoi Sadowski-Synnott topped their respective qualifying sessions in the slopestyle.
Harrington was disappointed with the score on his opening jump – a double misty pullback.
“This is crazier than some of our biggest finals events that we’ve had in big air, big ups to everyone,” he told Sky Sport.
“It felt really good. Came in with a plan and executed the plan and even got a bonus hit in the end. I’ve been working really hard on that first trick I put down tonight and it didn’t get rewarded the way I wanted it to. It’s been a big process and one of the hardest tricks I’ve ever worked through. That was a bit of a shame to see but it’s hard to compete against all these triple 19s and nosebutters … all sorts of stuff. It’s just such a pleasure to be part of this event and to be pushing the scores that we are.”