A hardy group of volunteers descended upon wind-swept Lake of the Isles in Minneapolis this weekend, thrilled that temperatures were crashing to record lows.

Their mission: to build 40 8-foot columns of ice that eventually will form an “Ice-Cropolis” enjoyed by thousands of participants in the City of Lakes Loppet ski race and festival this month.

Some years, it can take up to a week for the columns to build up the mandatory 4-inch-thick ice walls. This year, the walls could develop a solid core within 40 hours, volunteers said.

“We’re probably the only people you’d hear saying the weather is just perfect,” said Charlie Henke, a longtime Loppet volunteer.

He was among eight volunteers who maneuvered the tall cardboard columns into the ice Saturday. The group also worked Sunday, when staff from the Minneapolis Park and Recreation Board brought in equipment to pump water into the forms.

Later, the columns will be hollowed out and fitted with candles to light the way for lake skiers during the Luminary Loppet, one of the events held during the festival.

The fest, held Jan. 31 through Feb. 2, is overseen by the Loppet Foundation of Minneapolis.

Sturdy volunteers such as Henke think nothing of working during subzero temperatures, jamming towering cylinders 6 inches into the ice. The temperature must be 10 below zero for the cardboard towers to freeze solid, he said, so every year it’s an arctic endeavor.

What was he thinking outdoors on one of Minnesota’s coldest weekends in years?

“I’m thinking I hope this works because I don’t want to do this again,” he said with a laugh.

“You really have to be excited about the outcome,” he added. That “outcome” is creating an event that attracts thousands of amateur skiers, he said, not just the racers. “We had a guy stop by and tell us that the Loppet inspired him to cross-country ski after having a heart attack.”

Enduring a little arctic blast is a modest price to pay for outcomes like that.