On the Tour du Mont-Blanc, the weather cannot be read the way it is in the valley. Afternoon storms, early-season snow patches, exposed passes: knowing how to interpret the conditions is the skill that counts most on the ground.
Reading mountain weather
Always check a mountain forecast for the altitude of the passes (2,500 m), not the one for Chamonix. Focus on three things: the 0 °C isotherm, the time storms are expected to break, and the wind strength at the passes.
In summer, the golden rule is to start early: most storms break between 2 pm and 5 pm. A stage finished by 3 pm is a successful stage.
Snow patches and the early season
Before mid-June, several passes keep snow patches on their north side: the Bonhomme, the Col des Fours, the Fenêtre d'Arpette. These sections are not technical in dry conditions, but they can become slippery and exposed when snow-covered.
If you set off early in the season, take poles, ask the wardens, and keep the lower variants in mind: they exist for almost every pass.
Where to find reliable information
- Refuge wardens: the most up-to-date source on the real state of the trail
- The tourist offices of the three valleys for trail closures
- The conditions banner on this website, updated throughout the season
A postponed stage is never a lost stage: on the TMB, variants and valley shuttles almost always let you carry on with the Tour.