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How severe storms occur
A good three quarters of all building damage due to natural hazards are caused by hail, storm and heavy rain. In Switzerland, bad weather usually reaches us from the west – the front of a house facing west is therefore also called the “rainy side” or “weather side”. Storms also usually come from the west. Storms referred to as westerly storms occur when cold air from the polar region meets warm air from the subtropics – large-scale low-pressure systems form. Their intensity depends on the difference in temperature between the two air masses. This means that storms are most violent in the late fall and winter when the polar air is already very cold, but the oceans are still comparativelywarm. The highest speed of a gust of wind ever measured in Switzerland was recorded during the “Wiebke” hurricane on the Jungfraujoch in February 1990: 285 kilometers per hour. In a “normal” violent storm, the gusts of wind reach speeds of 160 to 200 km/h.
All forms of protection aren’t equal
High-quality building materials on the shell of the house that are adapted to the location offer protection from an impending storm or hailstorm. On the other hand, sunshades and slat blinds – or a cover on the swimming pool – only appear to offer protection. It is better to remove them before a storm threatens. In Switzerland, building insurance will cover damage to the windows, roof or house walls. The garden shed or summer house on the other hand is covered by the household insurance. This should be taken into account in the sum insured.
When renovating: check the hail register
The area most susceptible to hail in Switzerland is the Alpine foothills. Here in particular, it is useful to take a look at the national hail register. According to this hail register, every five to ten years on average a house will be hit by hailstones with a diameter of two centimeters, and every 20 to 50 years even by hailstones with a diameter of three centimeters or more – almost the size of a miniature golf ball.
The extent of the damage caused by these hailstones, which usually occur in combination with strong winds, depends on the materials the house walls are made of. More and more manufacturers now have their materials and building products entered in the hail register, which indicates their hail resistance. Good protection is guaranteed from level 3 or above.
Know where the weather side is
Of course, everyone likes sitting out in the garden to enjoy the evening sun. But this can be dangerous in stormy weather because garden umbrellas and chairs can become bullets. If there’s a storm warning (be sure to download one of the free apps “Meteo Swiss”, “SRF Meteo” or “Landi Wetter”), remember to take anything that is even remotely mobile to the basement or a sheltered place in plenty of time.
Regular preventive measures
If a gutter becomes clogged, water can no longer drain off. If there’s a hailstorm, the situation becomes even more unpleasant. Blocked gutters can cause water to penetrate the house or the basement. If this should happen despite taking precautions, it helps to use a submersible pump (from a water level of approx. ten centimeters, available in camping supply stores) or at least a wet vacuum cleaner (e.g. by Nilfisk, from about 260 francs at Jelmoli) and to have a water squeegee in the house (a squeegee with handle is available from Landi for around 25 francs).
Look after the garden
If there is a tree on your property, you are liable for any damage it causes during a storm if a broken branch breaks a window or damages the roof of the neighbor’s house. Check and maintain your trees regularly or get advice from a specialist. Sick and dead trees should be felled for safety reasons. The same applies to large flowerpots or flower troughs, as well as to garden furniture: if they are on the weather side of the house, you need to be able to secure them or move them in an emergency.