Temperature records are likely to be reached on Friday

Compared to previous years, May is too warm, too sunny and too dry – an exception that could become the norm.

A couple enjoys the warm weather in the shade under a tree on Landiwiese in Zurich, Switzerland, May 11, 2022.

Ennio Leanza / Keystone

After it was relatively cool in April, it is now clearly too mild – if not too hot – in May. If you compare the previous temperatures with the long-term average from 1991 to 2020, this May was around 2 degrees too hot in northern Switzerland and 1.5 degrees in southern Switzerland. A cool phase has not been recorded in May so far, and the ice saints have also failed completely, reports «Meteo News». Instead of cool days, several summer and even hot days with temperatures above 30 degrees have already been recorded locally. This development will continue in the coming days.

On Friday, a hot day can be expected in the lowlands, says meteorologist Roger Perret: “We expect 30 degrees and more in many places. Locally, we should even achieve temperature records since records began.” Temperatures of around 32 degrees are expected in Zurich on Friday, 33 in Basel, 30 in St. Gallen and 31 degrees in Bern. It’s a bit cooler in Ticino, where 29 degrees are predicted for Lugano.

So far almost 70 percent less rain in Lugano than usual

That it is so warm so early is not the first time. However, it happens very rarely. “Such high temperatures tend to be very unusual,” explains Perret. “We expect maximum temperatures of what is possible at this time of year.”

In addition to the high temperatures, it has also been far too dry so far. Southern Switzerland is particularly affected, where there has only been small amounts of rainfall since November 2021.

Deviation of previous temperatures in degrees Celsius from the average May climate mean since 1991

This year, almost 70 percent less rain fell in Lugano and in Locarno almost 65 percent less than usual. But also in northern Switzerland, significantly less precipitation than normal was recorded. In western Switzerland and central Valais, about half of the usual amount of precipitation fell.

The locally prevailing drought has an impact on the levels of rivers, lakes and groundwater. As an acute example, Perret cites Lago di Lugano, which has been below the absolute minimum ever measured since the second half of February. The low water levels are not only due to the current drought, but also to the low snow masses from last winter season and the lack of meltwater. The current situation would exacerbate the situation.

Deviation of rainfall in percent since the beginning of the year compared to the average since 1991

The number of hours of sunshine is also far above average. Comparisons with the long-term mean show that western Switzerland was far too sunny. In central and eastern Switzerland, in Graubünden and in southern Switzerland, the hours of sunshine are also above average – albeit not as clearly as in the west.

Extreme weather events are likely to increase

Such weather conditions – long dry seasons or extremely heavy rainfall, such as in summer 2021 – can be attributed to climate change, explains Perret. Of course, based on high temperatures, one cannot simply say: “This is now climate change.” After all, there have been hotter and colder periods in the past. However, the frequency and consistency of extreme weather is increasing, which means that it is sometimes too hot for weeks or, as in Ticino, hardly rains for months.

“Such constant, extreme weather conditions will increase in the future,” says Perret. This has an impact on the water supply, electricity production from reservoirs or on the retreating glaciers.

Perret predicts that the weather will be stable in the short term. After the high temperatures on Friday, the situation is likely to ease over the weekend and at the beginning of the new week: “Temperatures are falling and we are expecting some precipitation.”

A new high is already on the cards for the middle of next week, which will push temperatures back up. While this should cause further concern for meteorologists, it will probably please sun-seekers.

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