Twenty-six dog teams are leaving on the 1,600-kilometre race to Fairbanks, Alaska, travelling on frozen rivers, lakes and trails through the wilderness of central Yukon and Alaska.
This year's race is generating excitement because four former champion mushers, all Alaskans, are competing.
They include Allen Moore, who has won the past two years, and mushing legend Lance Mackey, who holds the record for the most wins with four consecutive victories between 2005 and 2008.
Other contenders could include Alaskan Brent Sass and Ed Hopkins of Tagish, Yukon.
Hopkins has been mushing for about 30 years and says the relationship between the musher and his or her dogs is a huge factor in a team's success.
"You rely on them and they rely on you, so it's like a really tight marriage. If you don't have the right bond or the right chemistry, you might have problems, it won't be a smooth ride," Hopkins says.
Mushers' bond with the dogs
Hopkins says his bond with his dogs is developed from their birth and with constant companionship.
"We socialize them, and we raise them all pretty much from pups until they're old enough to run races, and then you just build up their confidence slowly," he says.
"You never let them have a sour or negative time with you, it's all got to be positive." Hopkins says.
The mushers begin with a maximum of 14 dogs in their team, but usually some dogs drop out from fatigue, sickness or injury along the way. A team must have at least six dogs to continue racing.
Veterinarians assess the dogs at every checkpoint on the course.
The mushers and their dog teams will encounter steep summits, sleep deprivation and temperatures as low as –50 C along the way.
A challenging year for the trail-breakers
The preparation of the 1,600-kilometre trail begins in earnest in mid-January with separate crews on the Alaskan and Yukon sides of the border.
John Mitchell, of Dawson City, Yukon, and a member of the Canadian Rangers, has led the Canadian crew for many years.
"This has been one of the most challenging trail operations we've had since we started the Quest," Mitchell says.
One of the biggest headaches for the trail-breakers is jumble ice. It sometimes occurs during freeze-up when huge chunks of river ice collide, heave up and then freeze in place, leaving a jumbled surface that's extremely difficult for the dog teams to pick their way through.
Mitchell says they begin by laying a trail base and then keep improving it almost up to race day. But Mitchell says that doesn't mean their work is done.
"The only thing constant about the trail is change. It changes hourly, daily, weekly. It's totally on the move all the time," Mitchell says.
The Rangers run snowmobile patrols just ahead of the front-runners in the race looking for any safety hazards like fallen trees or open water that need to be fixed.
Each musher carries a tracker that frequently updates their position on the Yukon Quest website.
Echo Ross, a spokesperson for the race, says there were 183,566 views of the tracking site in 2014.
Yukon school children keep close tabs on the teams
In Yukon communities, many people will be following the race on the tracking page.
Cathi Dunham, a vice-principal at Selkirk Elementary in Whitehorse and a longtime volunteer in the Yukon Quest, says she introduces the race to the classroom every year, with each student being given a musher to follow.
"It's something the kids can really get into, they have a chance to go see the dogs leave, follow the trail, and just get a sense of a northern event," Dunham says.
The race also attracts fans from around the world.
Janine Breuer-Kolo, a radio show host from Cologne, Germany, quit her job and is on a yearlong cross-Canada trip. She's come to the Yukon to learn about dog sledding and to volunteer in the Quest.
She'll be helping out at the start line Saturday and says she's excited.
"There's so many people and the animals and when you just get to the point when it finally starts," Breuer-Kolo says.
"I mean people have been training for this and working on this for months now, or years, and there's rookies, there's veterans, there's so many people involved in all this, and so you just can feel how they get more and more excited the closer it gets to the start date," she says.
The Yukon Quest is sometimes compared to the better-known Iditarod sled dog race in Alaska.
They are both long-distance races over rugged terrain in often extreme weather conditions. The Iditarod is a much larger event, however, offering a purse totalling $725,100 U.S. this year and attracting almost 80 mushers, while the Quest has 26 teams and a purse of $127,110.