Long-term data series for temperature, precipitation and sunshine duration are available at MeteoSwiss. The data are obtained from 29 climate stations and 46 precipitation stations. For several locations, these data series date back as far as 1864 (Swiss National Basic Climatological Network). These long-term data series are extremely valuable for understanding climate change both in the past and the present. To ensure that man-made changes such as station relocations or the use of new measuring instruments do not have a confounding influence on the results, the measurement data are extensively checked for measurement errors and temporal homogeneity before being analysed (homogenisation). The resulting homogeneous data series from 1864 onwards and further information on this topic can be found here:

Statistical methods can be used to derive values from the measurements at the individual stations for any location in Switzerland where there is no measuring station. This makes it possible to create maps displaying the changes in temperature, precipitation and sunshine duration for the whole of Switzerland. In addition, they can be used to calculate mean values for individual areas.

So-called climate indices such as hot days or frost days are used to characterise the climate at a particular location or to illustrate the effects of climate change.