Switzerland has four distinct seasons and its climate varies considerably from one region to the next due, first and foremost, to topography and differing altitudes.
Owing to its central location in Europe, Switzerland finds itself at the intersection of several major climate zones. The Swiss climate is strongly conditioned by the relatively nearby Atlantic. Winds from the Atlantic transport moist and mild maritime air towards the Alps. These westerly winds mean that both winter and summer are mild, but they also bring rain throughout the year.
Switzerland's topography and wide-ranging elevations make it a country of microclimates. Depending on where you are and the time of year, conditions can sometimes be Siberian, sometimes Mediterranean.
Temperatures are conditioned by altitude and vary considerably in Switzerland. The average temperature on the Swiss Plateau is 1°C in January and 17°C in July. Ticino generally enjoys temperatures that are 2 to 3°C higher than those of the Plateau. The average temperature at an elevation of 1,500 metres is around -5°C in January and 11°C in July. At this altitude, precipitation in winter tends to fall as snow. Snowfall is rare in the lowest regions of western Switzerland (greater Geneva area), northern Switzerland (Basel region) and in the far south of Ticino.
The Alps act as a climatic divider between the north and south of Switzerland. The region has a multitude of complex microclimates, particularly in the valleys of Graubünden and Valais, which are especially dry. Another peculiarity of the Swiss climate is the “Foehn”. This down-slope wind blows over the Alps and keeps the climate very mild and dry from autumn to spring.
Since the early 1990s, recorded annual temperatures in Switzerland are above the average. All of the warmest years on record since 1864 date from 2001 onward. The year 2015 broke all records.
Switzerland contributes to international efforts to keep global warming in check. The Federal Act on the Reduction of CO2 Emissions aims to cut greenhouse gas emissions by at least 20% as compared with 1990 levels, by 2020.