When to hike the Tour du Mont Blanc
The TMB is hiked from about mid-June to mid-September: the window when huts are staffed and the passes can be walked. Each month has its upsides, and its traps.
Updated
Month by month
June
Huts open gradually from mid-June. Snow patches are common on passes above 2,400 m (Bonhomme, Seigne, Grand Col Ferret), and high variants are often impassable. Very long days, few people, flowers in the pastures. Bring poles and microspikes, and check every place is open.
July
Everything is open and the snow retreats fast. Busy, especially from mid-July. Frequent afternoon storms: start early.
August
Peak season: huts full, busy trails around Lac Blanc and Bonatti. Usually the easiest conditions, with heat in the valleys.
September
Often the best time: clear air, fewer people, autumn colours. Huts close gradually from mid-September, and the first snow can fall on the passes. Check closing dates.
The mountain year
The periods below give the order of magnitude. Dates change every year with snow cover, weather and each warden: none is guaranteed.
- October to mid-JuneOff season
Staffed huts are closed, sometimes with an unstaffed shelter left open, without meals or services. Snow covers the cols and conditions are wintry (avalanches possible): this is no longer a summer hike and needs equipment and real mountain experience. Only some valley accommodation stays open.
- Mid-June to early JulyGradual opening
Huts open one after another, each on its own date: the route may not be fully served at the start of this period. Snow patches are possible on the high cols, streams run high with meltwater, and the trails are quiet.
- July – AugustHigh season
Everything is open and the cols are usually clear, but this is the busiest period: huts are full months ahead. Afternoon thunderstorms are frequent (start early) and valleys are hot.
- Early to mid-SeptemberOften the best window
Fewer people, pleasant temperatures, most huts still open. In return: shorter days, cold nights at altitude and possible first snow on the highest cols.
- Mid to late SeptemberGradual closing
Huts close one after another, some at the start of the month, others towards the end. Check that every stage end still has an open place to sleep, especially at altitude.
When places open and close
There is no shared calendar: every hut, hostel or campsite sets its own dates and adjusts them from year to year. High huts open later and close earlier than valley ones.
At both ends of the season, check every stage end and keep a fallback in the valley. Current dates are on each place’s website; when in doubt, a phone call settles it.
- Staffed high-altitude hutsMid-June → mid or late SeptemberAbout three months. Exact dates are set by each warden, depending on snow.
- Hostels and mid-mountain hutsJune → end of September, sometimes longerOften a slightly longer season than the high huts.
- Village hotelsOften year-round, with an off-season breakMany close for a few weeks in spring and autumn: check.
- CampsitesJune → SeptemberEach campsite sets its own dates, usually tied to the summer season.
- Unstaffed sheltersOpen all yearNo meals, no booking, no services: bring everything you need to sleep and eat.
Snow on the passes
Even in midsummer several passes exceed 2,400 m: it can freeze at night or snow, and fog or storms build quickly. In spring and autumn, hard slippery snow patches can linger on north faces: poles and microspikes make the difference.
Before you go, ask about trail conditions at the Chamonix Office de Haute Montagne (Chamoniarde) or the local tourist office.
- 2,443 mCol de la Croix du BonhommeNorth side: late snow patches in spring, and from the first autumn snowfalls.
- 2,516 mCol de la SeigneFrance–Italy border, exposed to fog and sudden weather changes.
- 2,537 mGrand Col FerretItaly–Switzerland border, windy.
- 2,665 mCol des Fours (variante)Highest point of the tour, late snow: avoid early and late in the season.
- 2,665 mFenêtre d'Arpette (variante)Steep boulder field, dangerous when snowy or wet.
- 2,191 mCol de BalmeSwitzerland–France border, lower than the other big cols: it usually clears earlier.
Weather and storms
In summer the classic pattern is a clear morning followed by late-afternoon storms. The rule is simple: leave early (7 am or before) so the main pass is behind you by early afternoon. Check the mountain forecast the evening before and that morning.