The weather in the Alps: anything is possible
Nowhere the weather is more changeable than in the mountains. The Swiss Alps are the border between the cooler Northern European climate and the warmer Southern European climate. Therefore it often forms the separation between different kinds of weather. At the same time, cooler and warmer types of weather can be found in Switzerland.
At a regional level this is a known phenomenon too. While the sun is shining in one valley it may be raining at the other side of the mountain. The weather may also clear up very fast. A cloudy, drizzly morning does not necessarily have to be a sign for a full day of bad weather. There may be a cloudless sky within the hour. It goes the other way round as well, and on a beautiful day it may suddenly become cloudy and rainy. This certainly is something to take into account.
Temperatures vary a lot by season, location and elevation. Still, Switzerland's climate may be classified as mild. It is strongly influenced by the relatively nearby Atlantic. Winds from the Atlantic transport moist and mild maritime air into Switzerland. This results in a relatively mild climate. On average, the areas north of the Alps are cooler than the areas south of the Alps. South facing slopes receive more sunshine and are warmer than north facing slopes. Wide valleys and lakes receive more sunshine than narrow valleys. Elevation is what influences the temperature most. Every 100 m (328 ft) of gaining height can cause temperature drops of 0.7-1.0 °C (1.8 F). On mountain tops it may be chilly even in Summer and you may encounter thick layers of snow. In low sunny areas like Lake Geneva and the Rhône valley in the Valais, there is a Mediterranean climate in summer. Palm trees can be found in the sunniest region of Switzerland: the Lago Maggiore in Ticino.
- Warmest months: July and August;
- Warmest areas: Lake Geneva, the Rhône valley up to Brig, and the valleys in the south of the Ticino. All low elevation areas around lakes and rivers from the West to the North East (Geneva - Zurich - St. Gallen) are pretty warm as well;
- Coolest months: January and February;
- Coolest areas: all places high up in the mountains and the Engadine.
Rain and snow
Also the amount of precipitation is very variable. The Rhone valley in the Valais is one of the driest parts of the country, sometimes locally comparable to a steppe climate. In this dry and sunny valley, grapes, apricots and grapefruits grow. Most Swiss wine comes from this region too. The Engadine valley in the South-East is very dry as well, but it's at a high altitude and therefore quite cold. The alpine regions get the greatest amounts of rain and snow.
In general, there's more precipitation in the Western Alps, as clouds come in from the Atlantic and loose most of their water before reaching the South-Eastern parts of Switzerland (Lake Maggiore, Lake Lugano and the Engadine).
- Driest months: January and February;
- Driest areas: the Rhône valley and the Engadine;
- Wettest months: May to August;
- Wettest areas: all places high up in the mountains.
How to prepare
You'd best check the weather forecast on the evening before you have planned to do a trip. Double check the next morning. The local forecast, specifically for the town or region you wish to visit, may provide more details. Regardless of the predictions, the weather may change really quickly and dramatic differences between one valley and the next are no exception. Therefore it is best to be prepared for weather variations.
In Summer, you can expect temperatures of up to 35 °C (95 F) in the lower valleys. But it might as well be 15 °C (59 F) on a rainy day, while it can freeze on a high mountain top. You can have a week of rain as well as a week of cloudless skies almost any time of the year. In Winter in the mountains, expect temperatures around the freezing point, or well below.
Of course you'd pack thinner clothing in Summer, but the best advice for any season is to be able to dress in multiple layers. That allows you to adapt quickly when weather is changing through the days or when you visit higher areas. Also you want to have a rain coat, sun glasses and suntan lotion. A scarf and gloves are convenient in Winter or if you plan to visit mountain tops. Winter sports and hiking require their own specific gear and preparations.
If the weather is important to your vacation, you may want to carefully select the towns you plan to stay in. If you prefer snow covered towns or Winter sports, you need to visit Switzerland in Winter (mid December to March) and pick towns above 1,000 m. You can have a warm, sunny Summer all around Switzerland, but for the very best chances, you'd best stay in low regions in the south like Lake Geneva, the Rhône valley up to Brig (the Valais), Lake Maggiore and Lake Lugano.