The Canadian 21-year-old had never even previously reached the big final in a World Cup but having won his quarter-final and semi-final, he was lining up to challenge for a medal on home snow against compatriot Kevin Drury and German duo Daniel Bohnacker and Florian Wilmsmann.
Howden led from wire to wire to cross the line in first, ahead of current ski cross World Cup leader Drury in silver, as Bohnacker earned bronze.
Another Canadian, Brady Leman, won the small final to seal fifth spot as Drury’s silver was enough to extend his lead atop the overall standings.
There was a less surprising result in the women’s event as Cross Alps Tour winner Sandra Naeslund of Sweden took her second victory of the season.
Naeslund won her quarter-final and semi-final before skiing supremely in the big final to grab gold. Silver went to home favourite Brittany Phelan, while Naeslund’s closest challenger in the season standings, Fanny Smith of Switzerland, took bronze.
Naeslund now has 550 points in the overall standings, 79 points ahead of Smith, with Marielle Thompson – who won the small final in Nakiska – a further 22 points back in third.