2026 MARATHON DU MONT-BLANC PREVIEW: THE 42KM SKYRACE RETURNS TO CHAMONIX

The Marathon du Mont-Blanc returns to Chamonix from June 25 to 28, 2026, with eight races spread across four days and roughly 10,000 runners on the trails above the valley. The centerpiece is the 42km du Mont-Blanc on Sunday, June 28, a Golden Trail World Series fixture that draws many of the sport's leading mountain runners to one start line.

The weekend is organized by the Club des Sports de Chamonix, a non-profit association founded in 1905. Every edition fills early, and the 2026 program sold out months in advance, with only the children's Mini-Cross still open at the time of writing.

The 42km, the Weekend's Headline Race

The 42km is the race the elites come for. It covers 42 kilometers with 2,540 meters of climbing, a profile that has little in common with a road marathon of the same distance. The first half runs on fast, rolling trails. The second half turns steep and technical on the climb to the aiguillette des Posettes, the course's defining difficulty, before the run-in toward the Mont Blanc range.

Sunday's schedule sends the elite women off at 6:45 a.m. and the elite men at 7:15 a.m., with the rest of the field following the men. The first finishers are expected back in Chamonix around 10:45 a.m. The field is capped at 2,300 runners across six waves, and the organizers note that a runner with a UTMB performance index below 350 has little chance of finishing inside the 10-hour limit.

As a Golden Trail World Series race, the 42km carries series points and a place in one of trail running's most-watched circuits. The format rewards consistency across a season of short, mountainous races, which makes a strong result in Chamonix valuable well beyond the day itself.

A Festival of Distances

The 42km is the headline, but it is one race among eight. The weekend opens earlier and tests a wider range of runners than the marathon distance alone.

The 90km du Mont-Blanc starts first, at 4:45 a.m. on Friday, June 26, from the Place du Triangle de l'Amitié. With more than 6,000 meters of climbing on a loop of the valley's high ground, it is the most demanding race of the weekend and pushes well past marathon distance into ultra territory. The first finishers are not expected until mid-afternoon.

The KM Vertical, a short, near-vertical climb, runs Friday afternoon. Saturday brings the 23km and the 10km, the original Cross distance and its shorter companion, before the marquee 42km closes the weekend on Sunday. The breadth of the program is part of why Chamonix fills each June, drawing first-time mountain racers and series professionals to the same trailheads.

What Is at Stake

The course itself is the through-line. The 2,540 meters of climb on the 42km and the high, exposed terrain on the aiguillette des Posettes reward runners who can both move fast on runnable ground and hold form on a sustained, technical climb. Weather in the Mont Blanc massif can shift quickly in late June, and the compulsory kit list, which includes a waterproof shell and a survival blanket, reflects that.

For the Golden Trail World Series contenders, Chamonix is a measuring stick early in the racing summer. The event has grown from a single 23-kilometer mountain race in 1979 into a four-day festival, a history traced in the race's full origin story. The 2026 edition continues that arc, with the 42km again set as the weekend's main event.

The first elite results are expected Sunday morning, June 28. RuntimeRacing will cover the finish once official times are confirmed.