After weeks of cool, wet weather, summer has finally arrived in Switzerland with Monday recording the highest temperatures of the year.
The thermometer climbed to 34.4° Celsius in Reckenholz near Zurich, with the main cities also recording levels above 30°. The reverse side of the coin was that ozone levels increased dramatically.
The high temperatures followed the hottest weekend of the year - in stark contrast to last Tuesday when the thermometer had reached only 13°C.
According to MeteoSwiss, the mercury on Monday climbed to 33.6° in Basel, 33.2° in Zurich, 31° in Geneva, 30.6° in Bern, 30.9° in Lugano and 28.6° in Lausanne.
The national weather service spoke of "tropical" conditions with nighttime temperatures remaining above 25°C in some areas.
The spell of hot weather, which is expected to continue over the next few days, was preceded by weeks of wildly varying conditions.
In April, Switzerland recorded a heatwave followed by a period with heavy local thunderstorms.
MeteoSwiss said temperatures last month were 1-2°C warmer than average but there was also more rainfall than usual. A freak storm caused damage totalling hundreds of millions of francs.
Heavy rain in the first couple of weeks of July further raised the levels of rivers and lakes to the critical point, and destroyed or delayed the wheat, cherry and rapeseed oil harvest, particularly in western and northern regions.
With the arrival of higher temperatures, the focus is now on protecting the public. The authorities have issued a warning of the related health risks and preventive measures.
Ozone levels exceeded the limit of 120 micrograms per cubic metre of air in 14 of 16 measuring stations across the country, with the highest level (193) recorded in Lugano.
Old people, those suffering from chronic illnesses and very young children are particularly at risk from heatwaves, said the federal heath and environment offices in a statement.
The authorities are advising people to avoid physical exertion, to keep homes cool and to drink at least 1.5 litres of water per day.
In 2003, a record hot summer when temperatures edged above 40 degrees resulted in 1,000 more deaths than the normal summer average.
The cantons of Geneva, Vaud and Ticino have since installed a special alarm system to help look after particularly vulnerable people.
swissinfo with agencies
Swiss weather records
Warmest location: Locarno-Monti 11.5°C (annual average)
Highest temperature: Grono (GR) 41.5°C August 11, 2003
Coldest location: Jungfraujoch -7.9°C (annual average)
Coldest temperature: La Brévine -41.8°C January 12, 1987
Highest rainfall in 1 day: Camedo TI, 414mm September 10, 1983
Highest rainfall in 1 year: Mönchsgrat 5,910mm, 1939/40
Driest location: Ackersand VS 521mm (annual average)
Longest dry period: Lugano 77 days (from December 6, 1988)
Highest new snowfall (per day): Klosters 130cm January 29/30, 1982
Highest snow amount: Säntis 816cm April 1999
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