The climate of the Alps is the climate, or average weather conditions over a long period of time, of the exact middle Alpine region of Europe. As air rises from sea level to the upper regions of the atmosphere the temperature decreases. The effect of mountain topography on prevailing winds is to force warm air from the lower region into an upper zone where it expands in volume at the cost of a proportionate loss of heat, often accompanied by the precipitation of moisture in the form of snow, rain or hail.

Climate as a function of elevation

Because air cools as it rises, the climate of the Alps is strongly dependent on the elevation. The Alps contain a number of different kinds of climate zones, by elevation. These zones can be described by the Köppen climate classification, and also correspond to the biotic zones of the Alps. Up to approximately 1050 m of elevation, the climate is classified as oceanic or Cfb under the Köppen system. Like much of lowland northern Europe, the summers are mild and the winters are cool, but not cold. The climate is moderated by proximity to the Atlantic Ocean. The climate creates the colline biotic zone in the lowlands, which is characterized by the deciduous forest of the Western European broadleaf forests ecoregion. Between approximately 1050 to 1390 m, the climate changes to either a humid continental climate (Dfb under the Köppen system), or a subpolar oceanic climate (Cfc), depending on location. As elevation increases, the winters become colder and the summers become shorter. A mixture of conifer and deciduous trees occupy this montane zone, leading to a change in ecoregion to Alps conifer and mixed forests. Between approximately 1390 to 1880 m, the climate becomes subarctic (Dfc under the Köppen system), with even shorter summers. The shorter growing season shifts the forest to be purely coniferous. At about 1880 m, the climate becomes too cold to support trees, and is classified as an alpine climate (ET under the Köppen system). The summers become cool and only grasses and low plants are adapted to grow. This alpine climate extends to approximately 3250 m. Above approximately 3250 m, the climate transitions to an ice cap climate, where the mean temperature from 1976-2000 was always below 0 C. At these altitudes, no plants can grow and the ground is either rock or ice. At 3571m and from 1991 through 2020, Jungfraujoch had an ET climate, with an August mean temperature of 0.6 C. Glaciers, such as the Aletsch Glacier, still surround Jungfrau, but are starting to melt due to climate change.