Locals enjoy the frozen Lake Zurich during the Seegfrörni of 1963. Excerpt from footage shot by Adolf Borsari, 1963. NZZ / YouTube

The year Lake Zurich froze over

It's hard to imagine now, but it actually happened in the winter of 1963. Lake Zurich froze over entirely. The authorities opened the ice on 1 February, and the last public festival on the lake began.

Julia Hübner

Julia Hübner is a historian and curator of the Ortsmuseum Meilen.

Website: ortsmuseum-meilen.ch

A Seegfrörni on Lake Zurich is a rare and spectacular event. The Swiss German word describes a meteorological phenomenon, in which the lake is entirely, or almost entirely, covered in ice for more than one day. One particular year – 1963 – stands out in people’s memories because it turned the frozen lake into a fairground for all. For the whole of Lake Zurich to freeze hard enough to walk on takes 350 freezing degree days – degrees Celsius on days with a mean temperature below zero, added together (e.g. 35 days with an average temperature of ‑10° C). The last time the lake froze completely, in 1962/63, was the product of a cold snap in November, and a winter that was more than five degrees colder than average, with a total of 500 freezing degree days.

Dr. Hans Röthlisberger, glaciologist at the ETH Zurich, was brought in to test what the ice could bear. At an average thickness of 13 cm, it was opened to the public at noon on 1 February 1963. The lake police were responsible for safety, and posted rules about conduct on the ice. They became the ice police, equipped with skates, megaphones and radios. Reinforcements were brought in at weekends.

Load testing: five 200-litre barrels of water were placed close together on the ice, which promptly sank by 3.5 cm in the centre. After two hours, two further barrels were added, taking the total weight to 1,400 kg on three square metres. Although cracks appeared, the barrels sank so slowly that it would have been possible to jump to safety. Other barrels, placed some distance away from the central testing area, stayed put. The load test thus confirmed calculations that assumed that 10 cm would be the minimum safe ice depth. Keystone / Photopress Archive

It was the start of a weeks-long spectacle on 88 square kilometres of largely mirror-smooth natural skating rink. For weeks, the frozen lake dominated the lives and thoughts of those living and working around it. Thousands poured onto the ice to see the staggering sight of a solid Lake Zurich for themselves. Of course, this natural sensation soon became a tourist attraction. We can only guess at how many people were on the lake at once, but it is said to have been up to 150,000 at weekends. Children in the Lake Zurich catchment area were given an extra day off school so that they could really enjoy this unique experience.

**Frozen Lake Zurich on 27 January 1963.** ETH Library / Comet Photo AG
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**Thousands of people enjoying the frozen lake. Postcard with a view over the Utoquai lido, 1963.** Swiss National Museum
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**The frozen lake offered whole new ways of getting from A to B, whether on foot, by bike, or on skates.** ETH Library / Jack Metzger
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**Postcard commemorating the Seegfrörni of 1963.** Swiss National Museum
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**The ice at Meilen on 3 February 1963.** ETH Library / Comet Photo AG
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There were various ways of getting around on the ice, whether on foot, on skates, on skis, on sleds, by bike, or even in an ice boat. The lake police were the only ones allowed to use motorised transport, however. They zipped around on four snowmobiles provided specially for the occasion.

The frozen lake was also a paradise for sports fans. They pirouetted on their ice skates, held ice hockey, curling and ice football tournaments, and took part in the one-off Seegfrörni March. There was all sorts to choose from, including the first (and so far only) 42 km Zurich Seegfrörni Race, which was won by famous Basel speed skater Louis Rapelli.

Documentary on the Seegfrörni of 1963 and the first Zurich Seegfrörni Race (in German). NZZ / YouTube

The lake was dotted with stalls selling a wide variety of hot drinks, sausages and roast chestnuts, tobacco and pastries. You could even buy souvenirs like coffee cups, scarves, postcards and cigarette cases. Ice festivals were held everywhere, and as if the event weren't memorable enough in itself, you could have your picture taken with a polar bear. The local Zürisee-Zeitung newspaper echoed the Eiszeitung (‘Ice Times’) of 1880 and 1891 by publishing a special edition commemorating the event. Traditional carnival events also moved to the frozen lake, and an ice road led all the way from Rapperswil in the east to Zurich at the western end. Swiss Federal Railways (SBB) commissioned a film of the frozen lake at Zurich, using 1,000 local schoolchildren as extras. It was shown at the Expo 64 national exhibition the following year.

On 8 March 1963, the fun was over and the authorities closed the ice to the public. On the 25th, the Zürichsee-Schifffahrtsgesellschaft (ZSG), which runs boats on the lake, tried to speed the thaw using one of them, the ‘Wädenswil’ as an ice-breaker. It took weeks for the usual waves to return. The Seegfrörni of 1963 had been one big festival on ice. There will be cold winters in the future, but a changing climate makes it highly unlikely that the lake will freeze so hard ever again.

‘Antenne’, a programme broadcast on 4 February 1963 on the "Seegfrörni" on Lake Zurich (in German). SRF

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