Switzerland is enjoying its hottest June for over 50 years, with temperatures climbing as high as 35 degrees in some areas.
But the warm weather is not all good news: while many Swiss are enjoying the chance to swim in the rivers and lakes, others are suffering from the effects of the heat.
"These high temperatures are not really unusual in Switzerland," meteorologist Philippe Jeanneret told swissinfo. "But normally they occur later in the summer, in July and August, and it seems the early arrival of the heat wave has taken people by surprise."
Hospitals treat heat victims
At Bern's university hospital, the emergency department has been treating higher than average numbers of people suffering from circulatory problems as a result of the heat.
"Anyone with heart or blood pressure problems needs to take extra care," said Heinz Zimmermann, head of the emergency department. "We have been treating patients who weren't aware enough of the dangers of such high temperatures."
"We've also seen a lot of people with minor sports injuries," Zimmermann continued. "I can't prove it, but it's possible the heat may have affected their concentration and coordination."
Zimmermann offers the usual advice for enjoying the sunshine safely: "Wear a hat, use a high factor sun cream, drink plenty of fluids like water, avoid alcohol, and stay out of the sun during the middle of the day when it is hottest."
High ozone levels
Another factor is the level of ozone in the air, which tends to climb during periods of hot sunny weather.
Over the last few days, ozone levels have regularly exceeded Switzerland's limit of 120 micrograms per cubic metre. High ozone levels can cause breathing problems as well as irritated eyes and sinuses.
People with respiratory conditions such as asthma and hay fever are likely to be the most affected, while children and elderly people are also particularly at risk.
But Peter Straehl of Switzerland's department of the environment says short-term measures to reduce ozone levels, such as restricting the use of cars during especially hot weather, do not really work.
"If the ozone levels are regularly exceeding 120 micrograms, then we need to adopt new, long term measures," Straehl told swissinfo.
Diesel a big factor
"One thing which could make a difference would be to introduce stricter pollution controls for diesel vehicles, which are big contributors to high ozone levels."
Straehl's view is supported by Gaudenz Silberschmidt, vice-president of the Swiss Association of Doctors for the Environment.
"Short term measures won't tackle the roots of the problem," Silberschmidt told swissinfo. "We need to prevent ozone forming in the first place. So parliament should certainly not be thinking about reducing the price of diesel. And we should abandon the plan to build a second Gotthard tunnel."
Experts warn that even to keep the ozone at the level it is now, emissions from cars and other vehicles would have to be reduced by half - not just in Switzerland, but across Europe, since ozone doesn't recognise borders. And this, everyone admits, is extremely unlikely.
Same old message, same old sun burn
None of the warnings about over-exposure to the sun or dangerously high ozone levels are really new. Every time there is a heat wave, doctors and public health officials repeat the same message. But Heinz Zimmermann explains that human nature doesn't change either.
"After a period of cold rainy weather such as we've had here in Switzerland, people like to enjoy the sunshine," he said. "And it's normal, we don't think about health, we think about enjoying life."
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