Below you’ll find our Tour du Mont Blanc August conditions report for 2025. Make sure to bookmark our main Trail Updates page so you can get more information next season!

We’ll share information about current weather conditions on the TMB, and we’ll list a few of the major cultural events that are going on in the area. The information comes from our team of local guides, who are currently hiking the route. As always, we’ll keep updating this post throughout the month.

Each month we write a conditions report to help TMB hikers stay safe and prepare for their upcoming tour. As well as helping this year’s hikers, we hope to also reach anyone planning to hike the route in the future. So, if you’re planning a Tour du Mont Blanc in August 2026, or another year in the future, this post should still be useful, as we’ll include information about what to expect from a typical August in the Alps. To learn more about TMB conditions, read our posts from May, June, and July.

Disclaimer : In this post we’ll describe observations from our own Tour du Mont Blanc August trips. However, conditions change quickly in the mountains, and often with no warning! If you’re hiking without a guide, you are responsible for your our decisions! Of course, we’re happy to answer any questions, so feel free to leave a comment below. And if you’ve booked a self-guided TMB, contact us directly.

Tour du Mont Blanc August : general conditions

Because winter and spring were fairly dry, we started this summer season with less snow on the ground than previous years. June 2025 was warmer than normal, which meant the snow melted quickly from the high passes. There were a few small patches of snow in July, but now, in early August, the snow has completely melted from the TMB trails. If you’re hiking this month, you shouldn’t have to cross any snow!

The temperatures haven’t been particularly high this August. Perhaps because of this, we haven’t seen many thunderstorms yet. Our Tour du Mont Blanc August groups normally encounter more storms and afternoon showers than this year’s groups, but you never know… things might change yet!

Tour du Mont Blanc August water sources

As we mentioned in July and June, some of the water sources on the TMB dry up during periods of hot weather. At the moment, the following fountains have dried up :

• Refuge Balme before Col du Bonhomme
• Refuge Bertone
• Chalet Miage
• Col de Balme (this is still running but it is so slow that some hikers had to queue for 30 minutes to fill their bottles!)

The fountain at Refuge de la Croix du Bonhomme is also running low. Despite this , you can still refill your water bottles at least once a day, or else buy bottled water at the refuges.

TMB Shepherd Dogs (aka “patou”)

There are some new shepherd dogs in a field on the climb up to Col du Bonhomme, just before the Dames Anglais. They are with their sheep behind a fence, so don’t worry, you are safe! Just keep warming and talk to them calmly if you like… they might follow you up the trail and bark, which is unpleasant, but keep your cool and remember that they are safely behind a big fence! To find out more about shepherd dogs in the Alps, read this post about wolves.

TMB Variant Conditions

This year we’ve had groups hiking the more technical variant routes, such as Fenêtre d’Arpette, as early as June. These routes are now snow free, so if you’re an experienced hiker and the weather forecast is stable, challenge yourself and enjoy quieter trails.

tmb trail and weather conditions

As more groups set off, we’ll add details to this section, but in general the hiking conditions are very easy. The snow bridges that we detailed in June and July have melted away, and the rivers are not very deep.

The temperatures have been increasing, but at the time of writing (14th August) we’re currently having our first thunderstorm for weeks. The storm was forecasted, so it was easy for our groups to set off early enough to avoid it.

Because the TMB goes through a number of historical tourist towns, there are always cultural events going on. This month, look out for the following…

• 8th August : Summer tribute band
  Go to the Parc Couttet in central Chamonix for a free music concert, starting at 21:30
  
• 10th August : Organ Concert
  This is another free concert, starting at 17:00 in the Saint-Michel church, central Chamonix
  
• 12nd – 16th August : Guides’ Festival
  Join the Chamonix valley in celebrating their high mountain guides. Each town / village celebrates their guides on a different day, from Vallorcine to Servoz. There will be a number of free daytime activities, along with artisan stalls selling food and crafts. In the evening, each village / town puts on a free music concert. You can find a full program here.
  
• 15th August : Ultramontée des Posettes
  If you’re hiking the Posettes variant on this day, you’ll see participants of this running race! The event will take place between 9 – 16h, and runners will see how many times they can run up and down from Vallorcine during this time frame! It is a new event organized by the local running club.
  
• 20th August : Wine Tasting from around Mont Blanc
  Treat yourself to an evening of wine tasting in the historic Maison du Lieutenant building, Le Mont (Servoz). This event takes place from 17h – 19h, and tickets cost €15 per person. Book your place by messaging the organizer: +33 (0)6 61 85 63 86
  
• Ultra Trail du Mont Blanc : 25th – 31st August
  This huge event draws thousands of trail runners to the area every year. There are several ultra marathon events taking place, but the main event is the UTMB, which departs on Friday 29th August at 17:45 pm from Place du Triangle de l’Amitié. Join the festivities as fans and family members watch these incredible runners set off. If you’re hiking the TMB route during these dates, you will see lots of runners on the trail!