When there is thunder and lightning, the storm is near enough to endanger people who are out in the open. The shorter the length of time between the lightning and thunder, the closer the storm. The rule of thumb is: if you count the number of seconds between the lightning and thunder and divide by three, this gives the distance from the thunderstorm in km.
Advice on what to do in a thunderstorm, or if one is in the direct vicinity:
- Keep an eye on local weather developments, and act appropriately, according to the information you receive on the conditions;
- Heed push notifications on the MeteoSwiss App;
- Avoid mountain ridges, exposed trees, groups of trees, masts and towers, all of which are at risk of lightning strikes;
- Seek shelter – in a building or car (acts as a Faraday cage);
- If there is no shelter in sight, assume a crouched position;
- Do not go hiking in the mountains or walking in forests; avoid exposed locations;
- Stay away from metal objects and water;
- If a thunderstorm takes you by surprise when swimming, get out of the water immediately;
- Drive slowly on flooded stretches of road, or avoid these altogether;
- Avoid stream beds and steeply inclined slopes;
- Always follow the official recommendations.