On a national average, with three marked heat waves, the summer temperature exceeded the 1991-2020 norm by 2.3 degrees. Only “the legendary scorching summer of 2003” was warmer, with 3 degrees above the norm, writes MeteoSwiss on its blog. The second highest summer temperatures were recorded in all regions of Switzerland.
The first heat wave was particularly early, starting in mid-June. Northern Switzerland and the regions of Neuchâtel, Sion and Biasca experienced temperatures of over 36 degrees.
tropical days
The second heat period particularly affected western and southern Switzerland. It lasted from July 14 to 26 and is one of the longest periods of heat ever measured in Switzerland. The third scorching wave settled in the country in early August and peaked with 38.3 degrees in Geneva.
The country has recorded a large number of tropical days when the mercury exceeded 30 degrees – and this as early as May. Stabio, in southern Ticino, has totaled 59 so far, more than the 2003 record. In Geneva, Lugano or Sion, only the scorching summer of 19 years ago saw more days of high heat.
The mountain was not spared by the heat wave. The zero degree isotherm over Switzerland at a record high of 5184 meters on July 25.
Drought
As a corollary, the summer remained very dry, despite one of the wettest months of June since the start of the measurements. In some areas, notably in western Switzerland, less than 60% of normal rainfall amounts fell. Southern Ticino also experienced low values, below 40% of the 1991-2020 norm.
It was mainly in July that the rain was lacking, with in places less than 30%, and even locally less than 10%, of normal rainfall amounts. In the Geneva region, it is one of the driest Julys since the start of the measurements. The Jura vaudois has often recorded the driest month of July for more than 50 years, causing a pronounced drought.
