And the ongoing warmth played havoc, especially with the event's slalom. Eleven competitors failed to finish, and another was disqualified for missing a gate.
This run of mild weather might explain why two virtual unknown Swiss skiers now have gold medals at these Games.
In addition to Villeta, Dominique Gisin surprised everyone in the women's downhill earlier this week.
"They [track conditions] really make for funky results," said Ligety, the world champion in the event and, with Miller, one of the pre-race favorites.
"You can see the results sheet," Ligety said. "It's far from the World Cup result sheets. But we all have to ski and deal with it. There are no excuses."
Viletta, 28, was 1.64 seconds behind leader Kjetil Jansrud of Norway after the morning downhill.
The veteran Kostelic appeared to have the gold medal won at last, when his 51.37-second slalom gave him a combined time of 2:45.54, .12 seconds ahead of Innerhoffer.
But Valetta thrived where the other competitors had struggled. His 50.32 run was the day's second fastest, and it gave him the time that ultimately won, 2:45.20.
When victory became clear, a stunned Villeta, shaking his head and mumbling something to himself, turned a jubilant cartwheel.
"I can't describe what is going through my mind now," he said. "I was surely not a favorite. I guess the snow conditions and the course setting were perfect for me.
"But I still can't explain how I could ski so fast in the afternoon."
The unlucky Kostelic now has more silver medals - 4 - than any skier in Olympic Alpine history.
"This is great reward for me and my team given that I have really struggled this season," the slalom said specialist. "I felt I had a really good chance to win the gold medal after the downhill part of today's event, it was one of the best downhill runs in my career."
Miller, meanwhile, was 12th following the downhill. The 2010 champion in this event, he'd won that gold medal with a slalom comeback and, at the time, was confident he could do it again.
"It's going to be full-on attack, and whoever sticks it gets the medals," the 36-year-old American said.
His 51.93 slalom was the day's seventh-fastest but only good enough to move him into sixth place overall.
Ligety wound up 12th, with the 18th-best time in the downhill, eighth-fastest in the slalom.
So, more than midway through the Sochi Olympics, the only medal America's ballyhooed Alpine ski team has won is a bronze by Julia Mancuso in the women's combined.
The threat of more warm weather caused officials to move up the downhill's noon start noon by an hour.
By the time the slalom got underway at 3:30 p.m., the strong sun had left the course soft and mushy, conditions that most Alpine skiers dislike.
No mountain races have been canceled by this February warmth, but several practices have been postponed, and for some Rosa Khutor Extreme Park events, water has been applied to the courses.
International Olympic Committee members continued to stress that these unseasonable conditions were nothing new for a winter Olympics.
"What we have here is very similar to conditions in Vancouver," said Gilbert Felli, the IOC's executive director.
"You remember the problems we had at Cypress Mountain there? . . . There wasn't a centimeter or flake of snow in Vancouver, so I don't really see a difference."