HERMANTOWN, Minn. - Lots of people have more than one pair of pajamas, but Rudy Hummel may be the only 17-year-old who wears them all at the same time.
"This is a second pair of socks," says Rudy, as he dresses for bed in his room. "Three pairs tonight," he's decided - and "five to seven shirts."
Rudy brushes his teeth, says goodnight to his parents and walks out the back door into temperatures of -23. Then the Hermantown high school junior crawls into a snow cave and goes to sleep.
"You know when he gets seized by an idea he really goes for it," says Mark Hummel, Rudy's dad.
This is Rudy's grandest idea yet. He is sleeping outside every night for a year.
"It was just going to be the summer initially, but then I got to August, 'Geez, this has not been hard enough.'"
Rudy started out sleeping on a platform in a tree in the backyard. Then winter came and what's a Boy Scout to do but improvise. Rudy spent several days piling up snow in his backyard and then digging a narrow tunnel leading to a small bedroom.
"It's a quinsy," Rudy explains, "which is a type of snow shelter."
Sunday night, with outdoor temperatures at -23 degrees, Rudy's thermometer read 7 above inside his quinsy. His layers of clothing are augmented by several more layers of sleeping bags, blankets and quilts. Sunday night he also tucked a jug of hot water under the covers.
None of it is terribly surprising to Rudy's parents.
"The first time he tried to sleep out all night he was four," says his mother Gail Johnejack. "The first time he made it all night he was five."
Rudy has promised his mother he'll head back in the house if he ever gets cold. He hasn't even come close. Sleeping has been easy, especially under the sound deadening snow.
"The first night I was in here I kept hearing this soft thumping noise and I thought, I'd never heard that before, then I realized it was me blinking," said Rudy.
He'll wrap up his year of sleeping outside next June - no excuses. While traveling with his parents he's slept outside on hotel balconies and in his aunt's backyard.
Rudy Hummel is as committed at 20 below as he was last summer.
"Just to be able to tell myself that I did it at the end, to tell myself that I went a year without sleeping inside at night."