After a weekend of non-stop rain, a weather expert tells swissinfo that the country remains under an area of very low pressure and the rain is set to continue.
Thomas Bucheli, head of the weather service for German-speaking television, explains the situation and which regions are in greatest danger.
swissinfo: What is the cause of the current weather in Switzerland?
Thomas Bucheli: On Friday we saw a cold front making its way towards the Alps. That brought with it downpours and storms over a large area.
This caused a so-called cold front drop – a torrent of cool air – to move high above Switzerland. This resulted in further widespread downpours.
An area of low pressure has now formed over the Gulf of Genoa and is slowly moving over the eastern Alps towards northeast Europe, dumping a load of very damp air at the foothills of the Alps. This accumulation of damp air will continue to bring rain.
swissinfo: What next?
T.B.: The rain will gradually ease off over the course of [Monday]. I think the damp air will no longer affect the foot of the western Alps.
But a zone of this damp air will make its way towards the eastern Alps. People there can expect pretty heavy localised rain until this evening.
There will be intermittent breaks, but we shouldn't count on it easing up before this evening, when the low will move on along with the dampness.
swissinfo: Which areas are most threatened by floods?
T.B.: The most affected was the central plain – areas around Fribourg, Bern and central Switzerland. But a lot of rain has also fallen in canton Zug and the upper part of Lake Zurich.
Rivers in these areas have obviously been affected, too. At the same time, water levels in the eastern parts of the country, in the rivers at the foot of the Alps, are also really high – especially the Thur, but also the Reuss. In the next few hours the situation there is likely to worsen.
swissinfo: Is this a wet summer?
T.B.: August in particular was really bad. You couldn't help noticing that at the weekends and this probably gave people the impression of it being really wet. But there were occasional dry periods in between.
But I think that if we look at the summer as a whole, June was really beautiful and hot, July was average and now August is excessively wet.
A longer-term weather model reckons the autumn should be slightly "friendlier" and relatively warm.
swissinfo-interview: Christian Raaflaub
50-80 litres of rain per square metre had fallen by Monday morning in central Switzerland, the Bernese Oberland and the Fribourg Alps.
127 litres were measured in Napf.
Experts expect a further 30-50 litres to fall by Tuesday morning.