When the calendar flips to August, the Chamonix Mont Blanc region bursts into a vibrant mix of sunshine, mountain breezes and a dash of alpine rain. Visitors quickly learn that Chamonix August weather is anything but static – a single day can shift from clear skies to a brief thunderstorm, so checking the weather forecast becomes part of the adventure. The average temperature hovers around a comfortable 20 °C (68 °F) during the day, dipping to a crisp 10 °C (50 °F) after sunset, while the humidity level sticks near 60 percent. In short, this is the month when the high altitude meets high spirits, and the valley’s calendar is packed with the UTMB race, the Fête des Guides and endless opportunities for paragliding, trail running and mountain biking.
Below you’ll find a full‑blown weather guide that blends hard data – daily sunshine hours, rainfall mm, wind speed – with the very human side of planning a holiday in Haute Savoie. Whether you’re looking for a smooth summer lift pass experience, a safe hiking day on the Aiguille du Midi cable car, or simply want to know if you need sun protection glasses for the high‑altitude sun, this article has you covered.
Table of Contents
What the weather looks like in August
August sits squarely in the summer months for the Chamonix valley. The weather in August is typically characterised by a temperature range of 12 °C to 24 °C (54 °F‑75 °F). Expect clear skies for roughly 70 % of the month, interspersed with occasional mountain thunderstorms that can bring intense rain showers and gusty winds.
- Average high temperature: 22 °C (71 °F)
- Average low temperature: 11 °C (52 °F)
- Average rainfall: 45 mm (1.8 in)
- Average humidity: 62 %
- Average wind speed: 12 km/h (7 mph)
Even on a “sunny day”, the high altitude can produce a bite of cold at the peaks – think of a “cold night” feeling in the high altitude campsites, even after a pleasant afternoon. The weather forecast for early August often shows a daily max around 22 °C and a daily min near 9 °C, so layering is essential.
Average climate data and how it shapes summer activities
| Metric | Average | Typical August Value |
|---|---|---|
| Daily sunshine | 8–9 hours | 7.5 hours |
| Rainfall (mm) | 30 mm | 45 mm |
| Humidity % | 55 % | 62 % |
| Wind speed (km/h) | 10 km/h | 12 km/h |
These figures come from the weather station at Chamonix ski resort, which gathers data for the weather map and live radar services that hikers check before heading out. The “average daily” sunshine hours give you confidence to schedule a full day on the hiking trails or a biking trail excursion without fearing sudden darkness. Conversely, the rainfall mm and precipitation levels remind you to keep a rain jacket handy, especially when tackling the Vallee Blanche or the glacial sections of the Les Grands Montets circuit.
Notice how the “average temperature” sits comfortably below the heat‑wave thresholds that affect lower‑lying Alpine valleys. This means that the UTMB race runners can maintain a steady realfeel index close to the “feels like” temperature, avoiding the dehydrating effects of a heat wave. It also explains why the summer lift passes stay fully operational – the snow cover is minimal, but the “snow report” for August rarely mentions any snowfall days at the valley floor.
Outdoor events: from UTMB to Fête des Guides
August is a cultural and sporting feast in the Chamonix valley. The UTMB (Ultra Trail du Mont Blanc) kicks off the month, drawing elite athletes who conquer the temperature range of 12 °C to 23 °C while navigating steep ascents and the occasional gust from the mountain climate. The race’s official weather alerts are broadcast through a dedicated radar map so participants know when a storm chance rises.
Mid‑month the Fête des Guides celebrates mountain guides with a parade, live music, and local cuisine. It’s a perfect spot to learn about mountain safety and why a guide often carries a UV protection kit, especially at elevations above 2 000 m where the sun’s rays are intensified.
- Week 1 – UTMB race start and finish
- Week 2 – Guided tours of the historic Aiguille du Midi cable car
- Week 3 – Fête des Guides (music, food, mountain‑guide talks)
- Week 4 – Local music festival in the city centre, paired with a nightlife scene of bars and open‑air concerts
All events share a reliance on clear, predictable weather conditions. Organisers track the weather forecast with a minutecast** system that updates every five minutes, ensuring that if a mountain thunderstorm rolls in, plans can be shifted without compromising safety.
High‑altitude adventures: paragliding, hiking and more
For the thrill‑seekers, August is the optimum month for paragliding. The daily max wind speed of 12 km/h at mid‑altitude provides the gentle lift needed for long, stable flights over the Mont Blanc massif. The paragliding flight schools operate from the Les Grands Montets and run daily briefings that include a weather map**, a live radar map**, and a quick check on the UV protection levels – a must at high altitude.
A typical hiking itinerary might start with the cable car to the Aiguille du Midi, then follow the renowned hiking trails toward the Vallee Blanche. Even though the snowfall amount is negligible in August, the early morning can still bring a cold night** chill, so a down‑filled jacket is advised.
Mountain thunderstorms – what to expect
Mountains generate their own weather. In August, the mountain thunderstorms typically develop after midday, as the sun heats the valley floor and air rises rapidly. Their “storm chance” hovers around 20 % on any given day. If a thunderstorm is forecast, the best practice is to descend to a sheltered valley location before the cloud base reaches 2 000 m. Guides often recommend checking the weather alerts on the resort’s app for the most up‑to‑date precipitation levels.
Practical tips: sun protection, gear and mountain safety
Even though the average humidity sits at a comfortable 60 percent, the dryness at altitude can dehydrate you quickly. Hydration packs are a staple for any trail running or mountain biking outings. Pair your water bottle with a light, breathable layer that can be added when the temperature drops.
- Sun protection: wear a hat, UV‑blocking glasses, and reapply sunscreen every two hours.
- Clothing: layered system – base layer, mid‑fleece, and a wind‑proof outer shell.
- Footwear: sturdy hiking boots with good grip; the trails can become slick after a rain shower**.
- Safety gadgets: portable weather station or a smartphone app that shows the live radar and temperature forecast**.
For those planning a multi‑day trek, booking a mountain guide is advisable. They bring extra knowledge of climbing routes, can interpret the weather map**, and will ensure your group respects the delicate Alpine ecosystem.
Planning your stay: lifts, rentals and local highlights
Most visitors opt for a summer lift pass that grants access to the extensive cable‑car network, including the Les Grands Montets and the Aiguille du Midi**. Passes can be booked online and are usually valid from early June through late September. The lifts operate from 8 am to 6 pm, giving plenty of daylight for both hiking trails and the renowned cable car** rides.
When it comes to accommodation, the valley offers everything from holiday rentals in the city centre to glamping** sites perched on the mountain slopes. For a truly Alpine experience, consider a camping site near the Chamonix ski resort** – many are equipped with modern amenities and a convenient shuttle to the lifts.
| Service | Typical August Price | Where to Book |
|---|---|---|
| Summer lift pass (2 days) | €55 | Chamonix tourism office |
| Paragliding flight (incl. gear) | €120 | Les Grands Montets school |
| Mountain guide (full day) | €210 | Local guide association |
Don’t forget to check the weather guide section of the town hall’s website for weather alerts** that may affect lift operations, especially during those occasional thunderstorm days.
Frequent Asked Questions
How much sunshine can I expect in Chamonix during August?
On average, August delivers about 7.5 hours of sunshine per day, leading to roughly 225 sunny hours for the whole month. This makes it ideal for high‑altitude activities, though occasional cloud cover can reduce the total by a few hours.
Is the UTMB race suitable for amateur runners?
The Ultra Trail du Mont Blanc is a world‑class event that attracts elite athletes, but several shorter side‑races (e.g., the 26 km “Mont Blanc Trail”) are designed for recreational runners. The race organization provides detailed weather forecast** updates, allowing participants to gauge conditions before tackling the full distance.
Do I need special equipment for mountain thunderstorms?
While you don’t need a dedicated “storm kit”, carrying a lightweight rain jacket, a waterproof pack cover and a pair of quick‑dry socks is strongly recommended. If a thunderstorm is imminent, the safest option is to descend to a shelter below 1 500 m quickly.
What is the average rainfall in August?
The valley records roughly 45 mm of rain during August, spread across about eight rainy days. Rainfall is usually concentrated in short showers rather than prolonged downpours, so a quick umbrella or poncho often suffices.
Can I still ski or snowboard in August?
At the valley floor, permanent snow is rare in August. However, the glacier area around the Vallee Blanche retains enough ice for a limited “glacier ski” experience, typically offered only to certified guides.
Is sun protection really necessary at high altitude?
Absolutely. UV levels increase by roughly 10 % for every 1 000 m of elevation, meaning that at 2 500 m the sun feels significantly stronger. Wearing a high‑SPF sunscreen, a hat, and UV‑filter glasses will protect you from sunburn and eye strain.
What are the best places to stay for easy lift access?
The town centre of Chamonix offers numerous holiday rentals within walking distance of the main cable‑car stations. For a quieter night, the villages of Les Houches and Argentière provide chalet‑style lodging while still being linked via the lift network.
Making the most of your August in the Chamonix valley
Whether you’re chasing the thrill of the UTMB race, soaring above the peaks on a paragliding adventure, or simply soaking up the daily sunshine on a well‑marked hiking trail, August in Chamonix offers a balanced mix of pleasant average temperature and vibrant events. Keep an eye on the weather forecast**, respect the mountain’s sudden moods, and pack the right gear – especially sun protection and a reliable waterproof layer.
By planning around the weather in August – using the live radar, checking the humidity percent and wind speed – you’ll be ready for anything the Alpine sky throws at you. And when the sun finally dips behind Mont Blanc, a cool, clear evening in the valley invites you to unwind with local cuisine, a glass of Alpine wine, and the gentle hum of the high‑altitude night.
