The Swiss temperature mean describes the temperature measured on average across the entire area of the country and at the various altitudes of Switzerland. The data from different measuring stations is combined depending on how repre-sentative it is. The Swiss temperature mean is used to analyse and communicate changes in temperature in Switzerland over a period of many years.
Swiss temperature mean
Since 1864, the temperature has been systematically measured several times a day in various measuring stations scattered throughout the country. The series of measurements produced this way provides information about the temperature development at various locations in Switzerland over a period spanning many years. A mean temperature for all of Switzerland is used to describe the general development in the country as a whole.
Data on the Swiss temperature mean since 1864
The Swiss temperature mean is formed on the basis of monthly values. The monthly means and various aggregates (seasonal, semi-annual, annual) are available starting in 1864 at the link below and are continuously updated with the latest values.
From the station data to the Swiss mean
Using the station data, MeteoSwiss calculates the temperature for locations in Switzerland without a measuring station. This grid temperature data shows the regional distribution of the air temperature in Switzerland at a specific time or in a specific period. The mean of all these grid points gives rise to a mean temperature within reasonable limits in Switzerland.
The grid data has been available since 1981 in high resolution. But to still have the Swiss temperature mean available starting in 1864, it was analysed how the station measurements of the Swiss National Basic Climatological Network have to be combined to approximate the mean as closely as possible for the period from 1981 to 2014. Depending on how representative each station is for the Swiss temperature mean, it is assigned a weaker or stronger weighting.
The mountain stations Col du Grand St-Bernard and Säntis have the highest weighting. They are the only stations to represent altitudes higher than 2000 m above sea level in Switzerland. There are more stations available for the lower regions. These locations therefore have a lower weighting in the Swiss temperature mean.
Mean of lower regions of Switzerland
Switzerland is divided into different climate regions. In terms of temperature development over many years, the differences between the north side of the Alps and the south side as well as the different altitudes are interesting. As a result, a temperature mean is calculated for the following three lower regions using the same methodology as for all of Switzerland (CH): North side of the Alps lower than 1000 m a.s.l. (CH-NL), North side of the Alps above 1000 m a.s.l. (CH-NH), South side of the Alps (CH-S). The south side of the Alps includes, besides the Canton of Ticino, the Simplon region and the southern Grisons valley. The weightings of the stations shift accordingly and can even be negative.
Accuracy compared to the "real" grid mean
From the period with available, high resolution grid data from 1981 to 2014, only 20 years were used to determine the weightings of the measuring stations. The remaining 14 years were available to assess the accuracy of the Swiss temperature mean compared to the grid data. It is shown that the monthly values of the Swiss temperature mean provided can deviate by around ±0.1 degrees from the "real" grid mean. The potential error is generally smaller in summer and for the aggregates (seasonal, semi-annual, annual).