Only in International Falls does a 47-below-zero windchill day merit a steady stream of "likes" on Facebook.

Ken Krueger likes it, too.

Krueger and his wife, Jackie, are race directors of the Arrowhead 135 Ultramarathon, an endurance race that pivots on a paradox: The region's otherworldly cold makes the race what it is, yet that same extreme can mean its participants' undoing.

No matter. Another Arrowhead begins at 7 a.m. Monday in this frozen stretch of northern Minnesota, where more than 160 hardcore racers will set out into the wild along the Arrowhead State Trail and toward fates uncertain. By bike, by ski or by foot, their destination is Tower — or bust.

History shows fewer than half the competitors will finish, Krueger said. Last year, when the windchill at times bit into racers with minus-50 degrees, about 35 percent of the 141 who started made it to the finish at the Fortune Bay Casino. The first, by wheel, rolled in after 20-plus hours; the first runner, just over 43; the lone finisher by ski, 54.

Krueger can relate to the extremes and his flock: He has raced Arrowhead seven times since 2007, and by all three means. Early this month, he talked about the race, its informal beginnings and its robust, global following:

On his initiation to the Arrowhead 135: "I live in International Falls. There was just a little, little thing in the paper, 'Hey, they are having this race.' They had a racers' dinner, and there were 10 racers that first year [2005]. There were just the 10 racers and just a couple of family members and me. It's like, 'These people are really cool. I want to try this.' … The first chance I got was 2007, and that was the year it was the lowest finish rate ever. And that year I was the last biker in — I was the ninth finisher on bike, and there were only nine finishers on bike and one on foot."

On the race's evolution: "I think the difference is the applicants just keep getting better and better. The equipment gets better. People are better about sharing information, better prepared … Facebook, Internet, all that stuff. People share tips and ideas, and we have literally — to International Falls — people coming from all around the world. Just some elite-type people, so it's just really neat for the race.

"It's the same format every year, the same start time, the same checkpoints, the same gear requirements, a lot of the same volunteers."

On the extreme conditions: "That's what the racers come for. Last year, we had maybe a 35 percent finish rate, and I am going to say literally every person I talked to — and the ones who dropped out after 30 miles — shake my hand and say, 'Hey, that was awesome. I'll be back next year.'

"I don't think there is anyone who wants to come to have perfect trails and warm weather and just coast to the finish."

On the challenge: "On our Facebook page, last year we had 1,500 'likes' and now we have 4,000. Some of the stuff I'll post, like the roster, I think we had 21,000 people look at it. The race fills up real quickly. We could get a lot more people, but we cap it. ... Strength, endurance, solitude, survival — that's on the T-shirts and part of the [race] motto. If you get in trouble, you've got to figure it out yourself. Whereas if there are 1,000 people, somebody is five minutes behind you, and they are going to help you out.

"My first year, I probably went 20-24 hours without seeing a single person. … When you leave International Falls, you virtually don't see a house until the finish line. And you don't cross a lot of roads. … We have a contact list and we have volunteers patrolling on snowmobiles, but you're not going to see a snowmobiler every five minutes, it might be every five or six hours. We're looking out for you, but we're not babysitting you. And if your cellphone isn't dead and if you have reception, we have emergency contacts."

On comparing weather years: "Last year was one of the hardest ones we've had. We've had three years with really low finish rates. Last year was the third-lowest finish rate [35 percent], and it was because of the cold. But 2007 was the lowest finish rate. It was brutal cold and very poor trail conditions. 2012 was also a low finish rate. We had eight to 10 inches of heavy, wet snow during the race. You just worked really, really hard and got really wet and cold to go really slow."

On weather as game-changer: "For sure."

Bob Timmons: 612-673-7899