This small, mountainous, landlocked country has a wide variety of climatic conditions because of its great range of altitude. The higher peaks of the Alps rise to over 4,000 m/13,100 ft and are snow-covered throughout the year. At lower levels in the Alpine valleys and on the central Swiss plateau, summers can be quite warm, but this is the wettest period of the year in Switzerland. Much of the summer rainfall is heavy and is often accompanied by severe thunderstorms.
Like other parts of west-central Europe, Switzerland is open to climatic influences from the Atlantic and from eastern Europe, and the weather at all times of the year is changeable. The most settled weather occurs when the country is influenced by an anticyclone. In summer this brings warm, sunny weather, but in winter it may bring either cold, sunny weather or easterly winds with cloudy skies. Midwinter, rather than midsummer, is more likely to be a time of settled weather.
The country can be divided into four climatic regions: Canton Ticino or the extreme south, the Alps, the central or Swiss plateau, and the Jura Mountains.
This small area around lakes Maggiore and Lugano is the warmest part of the country in summer and at low levels the winters are relatively mild. It lies south of the main Alpine ranges and is, from time to time, influenced by warmer Mediterranean air. Summers are rather similar to those of the adjoining north Italian plain but are distinctly wet, with the rain occurring in heavy downpours. In settled weather it can be quite hot and sunny here. At low levels prolonged frost is rare in winter (see the table for Lugano).
Including (with towns and cities in parentheses) Valais (Zermatt), Graubünden (Chur, St Moritz).
The Alpine ranges cover half the country and extend from Geneva to the Austrian border. There are great differences between the climate of the valleys and the higher mountains. In winter the valleys are frequently cloudy and foggy with persistent frost. By contrast, during settled weather, the mountains are relatively sunny and daytime temperatures may feel quite warm. In winter the climate of the winter-sports resorts is thus more pleasant than that found in the valleys or on the Swiss plateau. In summer, conditions may be quite the reverse: the mountains shrouded in cloud by day and the valleys basking in warm, clear weather.
In fine weather a number of local winds occur in the Alps. In the large valleys there is a tendency for daytime breezes to blow up the valley and for a reverse down-valley wind to occur at night. Near glaciers this night-time wind can be very cold. A more widespread wind known as the föhn can affect large areas of the Alps under certain meteorological conditions. It is a warm wind, bringing air of very low relative humidity. Although it can blow in valleys on the southern side of the Alps, it is more severe on the northern side and blows particularly where valleys run from south to north. It is most noticeable in late winter and spring and can melt snow very quickly. At higher levels it can trigger dangerous avalanches, and at lower levels the very dry air and strong wind increase the fire risk to wooden buildings. With the onset of a föhn wind temperature may rise as much as 15°C/27°F-20°C/36°F within an hour. Such conditions may last for two or three days (see the table for Santis).
The Central Plateau
Including (with towns and cities in parentheses) St Gallen (St Gallen), Zürich (Zürich, Winterthur), Lucerne (Lucerne), Solothurn (Solothurn, Olten), Basel (Basel), Bern (Bern, Interlaken), Fribourg (Fribourg) Vaud (Lausanne), Genève (Geneva).
This is the lowest part of the country, extending from Lake Geneva to Lake Constance. All the large towns of Switzerland and the majority of the population are situated here. Winters are generally cold with much persistent low cloud and fog. Conditions are very similar to those in the deeper valleys in the Alps. During severe winters freezing conditions may last for several weeks with frequent snow. Snow is common during milder and changeable winters. The summers are generally warm but rather wet. Summers can vary considerably from year to year in terms of the amount of cloud and the number of wet days. During wet spells in summer the rain can be heavy and prolonged. The table for Zürich is representative of this area.
The Jura Mountains
Including (with towns and cities in parentheses) Neuchätel (Neuchätel, La-Chaux-de-Fonds), Jura (Delémont).
This small, narrow part of Switzerland extends from Basel to Geneva along the French border. The Jura rise to less than half the altitude of the Alps, but the valleys are narrow and the ridges steep. This area is rather wetter than the Swiss plateau and in winter the mountains carry snow for long periods. In some enclosed valleys winter temperatures can sometimes sink very low as cold air drains into the valley bottom. Summers are similar to those on the Swiss plateau but rather more cloudy and wet.
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