This chapter presents the main climate features in Switzerland for several parameters that might influence geomorphological elements and processes. In addition to altitude, the complex topography of Switzerland strongly influences air temperature and frost frequency by favouring cold air accumulation in the bottom of valleys and depressions. The Alps and Jura Mountains also generate cloud accumulations by orographic forcing and foehn effects that strongly influence mean precipitation and snowfall at a local scale. This chapter also presents variations of these climatic parameters in connection with the global climate warming observed in Switzerland for about a hundred years and particularly since the late
1970s as well as some projections for the future.