A steel cable on a rock face is an excellent conductor… and the worst place to be during a thunderstorm. So the weather is the first thing to check before a via ferrata, well before the grade. Good news: in the mountains, most storms can be forecast.
Before you go: the golden rule
- Storm risk forecast = don't go, or choose a very short route you can finish well before. A storm warning in force means no.
- Check the mountain forecast, not the one for the town: at altitude the weather changes faster and storms form more easily. On every ViaTrek route page, the weather is live for the exact location of the via ferrata.
- Set off early. In summer, storms mostly build in the afternoon, as warm air rises. Being off the route by noon or 1 pm is a good habit.
- Note the escape routes on the sign or the route page: they are your emergency exits if the sky turns.
- In spring and autumn, also think about snow and ice that may linger on high routes.
Warning signs
- clouds swelling upwards (cauliflower-shaped), turning dark grey at the base.
- The wind picking up or changing suddenly, a drop in temperature.
- distant thunder : count the seconds between the flash and the thunder and divide by 3 to get the distance in kilometres (9 seconds ≈ 3 km). If you can hear it, the storm is already close enough to be dangerous.
- Crackling in the air or on the metal, hair standing on end: immediate danger.
At the first sign, don't wait: take the next escape route or turn back if that is shorter. Storms often arrive faster than you think.
If a storm catches you on the route
- Leave exposed places : ridges, summits, footbridges, monkey bridges, isolated rocks.
- Move away from the cable as soon as you are on safe ground (wide ledge, path, flat area) where you cannot fall. As long as you are on a section where a fall is possible, stay clipped in : a fall is a surer danger than lightning. Simply avoid gripping the cable when you don't need to.
- Crouch down, feet together, sitting on your rucksack or a rope to insulate yourself from the ground, and wait for the storm to pass. Keep at least 1.5 m between you and the rock face.
- In a group, spread out a few metres apart so that a single strike doesn't hit everyone.
- Cover up: rain and hail quickly bring the temperature down, and wet rock becomes slippery.
- Only carry on once the storm has moved well away, carefully: wet cables and rungs are slippery.
In case of accident or if you are stuck: 112 (and 1414 in Switzerland).
Rain, wind, heat: the other traps
- Rain : slippery rock and cables, cold hands. An “easy” route becomes much harder.
- Strong wind : it throws you off balance on footbridges and makes handling carabiners harder.
- Heat : a south-facing wall in summer can become an oven. Set off early, take plenty of water and choose shaded routes or ones in gorges.
To prepare your outing, also read Getting started with via ferrata and check the live weather on the page of your via ferrata.
Going further
Sources consulted: Swiss Alpine Club – via ferrata safety · Outdoor.ch – weather on a via ferrata · Lacrux – mountain storms, 5 tips · FFME – via ferrata recommendations (PDF, in French).
This guide gives general advice. It does not replace training, the instructions posted at the start, or a professional's advice.