The Chamonix valley is located in the north-west of the French Alps and is home to the highest peak in Western Europe – Mont Blanc at 4810m. The presence of this towering mountain has a strong influence on the Chamonix weather system throughout the year. Chamonix town centre is at an altitude of 1,035m above sea level.
Introduction to Chamonix weather
Chamonix benefits from four distinct seasons, which is why so many of our guests love to visit time and time again at different times of year.
Spring is bright and fresh as the winter fades away and the temperatures rise, but snow can linger on the tops of the mountains well into the warmer months. Chamonix summers are warm or even hot, with dramatic storms often cooling things off in the late afternoons or evenings.
Autumn is often a quiet period with stunning scenery as the trees turn golden, and then the mountains start to slowly turn white as the snowline creeps further down. The winter season is white with snow falling all the way down to the town centre, and maximum daytime temperatures averaging around 2-7°C.
The mountain climate means that, as a general rule, Chamonix weather is wetter and cooler than the national average, though in winter that precipitation almost always falls as snow. The summer offers a great contrast with temperatures that can regularly reach 30°C.
In winter, you’ll notice that the valley floor and town centre tend to stay cool for most of the day, as the sun is lower in the sky and therefore has less direct contact to warm up the air. In contrast, many of the slopes will feel warmer if they are in the sun and there isn’t too much wind, as the sun warms the air up. This also causes cold to sink to the bottom of the valley as it is denser than the warmer air which forms around the slopes.
In the summer, the temperature in the valley is generally warm or hot, getting cooler as you gain altitude. Days will often be very warm in the valley or if you’re walking or biking in the mountains, although if you’re going to be going very high – for example to the top of Aiguille du Midi – you’ll still need some warm layers.
Summer also brings more risk of thunderstorms, one of the most spectacular Chamonix weather sights which you can enjoy from the comfort of your accommodation, against the backdrop of the mountains. You’ll often see them approaching from one end of the valley, a wall of black cloud looming ominously, and then an explosion of beautiful lightning strikes.
What causes summer mountain thunderstorms?
Thunderstorms are often a welcome interlude in the summer months, as temperatures rise during the day, and the thunderstorms cool the Chamonix weather back down again. Thunderstorms are created when warm, moist air meets cold, drier air. The warm air rises, which causes it to cool and the moisture condenses, forming clouds.
The collisions of particles in the cloud cause the cloud to become electrically charged. The discharge of this energy is lightning, and the thunder claps that we hear are caused by the lightning which causes vibrations in the air around it.
Don’t forget as well – in winter and summer – that the sun’s strength can be misleading at altitude, as it may not feel hot but your UV radiation exposure is much increased (UV radiation exposure increases 4 to 5 percent with every 300m above sea level – source). Not only will you need to wear more sun cream to protect your skin, but you’ll need good sunglasses to protect your eyes too from snow blindness. Be aware that the sun will penetrate even on a cloudy day, and the rays are also reflected back off the snow so sun protection is essential.
Our tallest mountain peak, Mont Blanc, has a huge influence on the Chamonix weather, and is also a natural barrier. As such conditions can often be very different in Courmayeur, on the Italian side of Mont Blanc, to how they are in Chamonix – great if you’re hoping to make the most of your 3 countries ski pass (Mont Blanc Unlimited) in winter on a ski away day!
Chamonix weather month-by-month
The below information on Chamonix weather is intended as a guide only, to give you an idea of what to expect. It is based on previous weather conditions, our own experience and anecdotal information but is not a substitute for accurate Chamonix weather forecasts – see below for our recommendations of where to find more information.
December – December announces the start of the winter season with the snow line getting lower and ski areas opening. The snow cover varies from year to year but there’s often a good build-up all the way down to town by Christmas. Cold temperatures mean that, even if the snow levels are not built up yet, the snow cannons can be working to make sure that the resort is ready to open for the start of the winter season.
January – January is usually a great month for snow, with cold temperatures ensuring that the snow that does fall sticks around. It can get chilly on the chairlifts so you’ll be glad of your helmet or a good hat, however the cold keeps the snow in great condition so you’ll be able to enjoy some great snow on quiet pistes, once the rush of New Year is over.
February – the Chamonix weather starts to warm up a little in February as we welcome families on their school holidays. However the snow also keeps falling so that ski conditions are great and the depth of snow on the mountain keeps increasing, meaning that off-piste runs like the Vallée Blanche become more accessible too.
March – as the school holidays finish, it’s a good opportunity to catch some early spring skiing, with the days getting longer and the sun getting warmer in the sky. The snow depths are still good too, with snowfall still expected to top up the existing base.
April – Easter holidays mean that families are back in Chamonix in April, making the most of more spring skiing on the mountains as well as opportunities for sunbathing and enjoying the spring flowers which start budding in the valley floor.
Not a bad spot for some lunch #grandsmontets #chamonix #welovechamonix #ski #snowboard #bluesky #sunshine #bluebird #nofilter #planjoran #springskiing #chamonixweather A photo posted by Chamonix All Year (@chamonixallyear) on
May – the last day of the ski season is usually the first Sunday in May, when Les Grands Montets will host a raucous closing party! Snow will linger at high altitude but trails along the valley floor and lower altitudes will be enjoyable for walking or biking. Days are likely to be warm, but evenings will feel cool after the sun sets.
June – June continues to get warmer, melting snow on the higher walking trails, but snow can stick around well into July so it’s always best to check the latest conditions with the High Mountain Office before heading out. From June, you can start enjoying the summer activities on offer – from climbing to water rafting – as the conditions improve and before the town becomes busier with summer visitors.
July – the Chamonix weather will be warm or hot in July, often building up into sultry afternoons and evening thunderstorms. All of the summer activities are possible at this time of year, and rafting or canyoning are the ideal ways to cool off!
A photo posted by Chamonix All Year (@chamonixallyear) on
August – August is similar to July, though perhaps even a little hotter in the middle of the day. The town is also busy, so we recommend getting some altitude for fresher air and to escape the clouds.
September – once the busy summer season has passed, September is a beautiful month. The town centre is quieter but the Chamonix weather often stays beautiful, making it a great time for biking and climbing, as well as enjoying end-of-summer walks with many of them still accessible on the lift system.
October – the autumn colours really come into their own in October, with the trees turning all shades of gold, yellow and red. The Chamonix weather is likely to be cooling down, perhaps with some rain fall too, but it won’t usually be cold enough for snow yet.
The clouds are clearing and revealing the latest dusting of snow! Loving the autumn colours too! #chamonix #welovechamonix #snow #ski #snowboard #winteriscoming #winter #autumn #fallcolors A photo posted by Chamonix All Year (@chamonixallyear) on
November – the end of autumn can still offer some lovely days, and as the mercury drops further snow may start falling at altitude. If snow conditions are really good, the higher slopes at Les Grands Montets may open at weekends at the end of November, though more often this happens in early December.
Webcams for Chamonix
Webcams aren’t a substitute for checking the Chamonix weather forecast, but if you just want a last-minute glance at the conditions before you head out in the morning, check out our webcam page.
Chamonix weather forecast
Check out the latest Chamonix weather forecast on our website or try it yourself with some of these traditional weather prediction techniques!
Folk wisdom tells us that a bumper season of red berries on the trees in autumn means that a cold winter is on the way, so we always keep our eyes peeled to see what the trees are telling us in the months before the winter season! There may not be any scientific logic to this old wives’ tale, but it’s as good a way as any to have an idea of what’s coming for the season ahead, as it’s so hard to do a true forecast more than about two weeks in advance.
Another piece of knowledge which has been passed down through the generations concerns “Mont Blanc’s hat” – a phenomenon which is found across the Alps. If there is a cloud settled on the top of the highest mountain in the region – in our case, Mont Blanc – which descends and starts to cover the mountain, then the Chamonix weather is turning and bad weather will usually follow. The cloud is actually a sign of humidity rising, or of stormy weather forming at high altitude.
Chamonix weather experts have an extra tip about this too – “If it doesn’t reach the Verte, Mont Blanc won’t be disturbed” (“Si Verte ne veut, Mont Blanc ne peut”). Even if Mont Blanc is wearing its hat, if there isn’t one on the Aiguille Verte as well – at the lower altitude of 4,122m – then it was a false alarm.
Some old farmers’ advice also rings true in Chamonix – “When clouds appear like towers, expect frequent showers.” Large, white, fluffy clouds harbour a lot of dynamic weather so showers are fairly likely if you see them building up in the sky. If they start to turn grey and swell, then they’re likely to turn into thunderstorms too, as you read above!
More about Chamonix weather
Latest Chamonix weather reports: Chamonix-meteo.com.