We’re on the ground in Chamonix, France, to bring you behind-the-scenes coverage of the weeklong series of races and the circus surrounding them.
(Photo: Courtesy UTMB World Series)
Updated August 25, 2025 08:29AM
Yes, the main event this week in Chamonix, France, is the 174-kilometer (106-mile) whole enchilada (or should we say baguette) around the Mont Blanc Massif, otherwise known as UTMB Mont-Blanc or simply UTMB on Friday, August 29. But it’s a week-long circus of racing, not to mention fun runs, speakers, demos, and spandex-clad people watching as this sleepy ski village of 10,000 swells to 75,000 for the de facto world trail and ultrarunning championship of the year.
With no less than eight UTMB-related races taking place beginning on August 25, including the 186-mile PTL, the 92-mile TDS, the 35-mile OCC, and the 63-mile CCC races, it’s a charcuterie board of stunning alpine vistas, pain (and pain) and triumph. (We broke down the races to help you make sense of the alphabet soup, check our Guide to the 2025 UTMB Mont-Blanc.)
But beyond the hundreds of miles of racing and 10,00o-plus racers, at any given moment, there’s a good chance that there’s a race start happening, while another race is finishing, while a trail legend is taking a small group out for a pre-race shakeout.
To help trail fans not fortunate enough to be stationed at the base of Mont-Blanc on UTMB race week, the Outside Run team is on location, bringing you everything from the latest race news and results, to spy shots of new gear, insider events, and more. Check back in our weeklong live blog often to see what’s going on in the Chamonix Valley this week!
Bonjour from Mont Blanc! We’re on the ground in Chamonix, France, to bring you behind-the-scenes coverage of the 2025 UTMB World Series Finals. Tune into the free livestream on OutsideTV starting on August 29 at 2:30 a.m. ET/August 28 at 11:30 p.m. PT. Outside+ members can watch the on-demand replay at any time.
2025 UTMB Mont-Blanc Race Week Schedule
Scroll down for our live, boots-on-the-ground updates throughout the week in Chamonix:
3 p.m. on Monday: TDS Rerouted Due to Storms
TDS, the extra-technical “cool kids” race that starts at 11:50 p.m. tonight, has been rerouted due to incoming thunderstorms storms, UTMB World Series officials announced this afternoon. The section between La Gittaz (73K) and Beaufort now takes a less exposed route. It also means racers need to run an additional 5K to make it to the finish line.
“Our teams and meteorologists have reviewed all contingency scenarios and approved the option that avoids the most exposed areas while preserving as much as possible the race experience and spirit,” race organizers said.
The updated stats on TDS: 153K (95 miles), 29,500 feet of vert.
1:40 p.m. on Monday: MCC Won by 17 Seconds
As a race devoted to locals and volunteers, MCC may be one of the “lesser” events of the week. But you wouldn’t believe that based on the throngs of supporters dressed up, holding signs, and ringing cowbells out on the grassy cols along the course.
Yoann Stuck (France) won on a sunny, 70-degree afternoon in Chamonix. He covered the 40K (25 miles) and 7,500 feet of climbing from Martigny Combe to Chamonix in a blistering 3:40:10. Stuck didn’t have long to celebrate at the finish—Léo Tuaz (France) crossed the line in second just 17 seconds later. And third-place Clément Génot (France) finished just 90 seconds behind him.
At age 40, Stuck’s victory was one for experience.
Marine Quintard (France) held onto an early lead to triumph in the women’s race in 4:16:24. She celebrated with a coke and an ear-to-ear smile at the finish as she waited for Pauline Giradet (France) and Iris Pessey (France) to finish five and 10 minutes back for second and third, respectively.
8 a.m. on Monday: PTL Begins
Mont Blanc in all of her pearly white glory smiled down on Chamonix this morning for the kick off to race week. That began with PTL, aka Petite Trotte à Léon, the 300K (186-mile) partner race that covers rugged, unmarked, largely glaciated terrain around Mont Blanc.
At 8 a.m. on Monday, 118 teams of two and three began their quest from the UTMB arch. It’s splitter weather right now—60 degrees and sunny. But it looks like it’s going to take a turn tomorrow, with rain and possibly snow up high coming tomorrow and hanging around through the rest of the week.
Named for an adventurous French baker and hardcore volunteer, PTL takes many teams the allowed 151 hours to get to the finish line in Chamonix. The course changes every year and there is no official winner. In fact, the event is so challenging that finishing is judged as a win.
Follow their progress here.
