Wind

Wind is the movement of air in the atmosphere, generally in a horizontal direction. Wind is created as a result of differences in air pressure between air masses of varying temperature. The air moves from the higher air pressure (high-pressure area) to the lower air pressure (low-pressure area) until the air pressure is balanced out. In Switzerland, westerly winds, called Bise (cold, north-easterly) and Foehn (southerly) are the most common types of wind occurring across widespread areas.

Hazard category 5 (very severe hazard)
Impact
  • Falling trees or entire groups of trees or sections of forest as well as electricity pylons and poles.
  • Severe damage to buildings.
  • Road, rail, water and air traffic disrupted or at a standstill.
  • Toppling of larger (empty) vehicles.
  • Securely anchored objects with a larger surface area, such as tents and scaffolding, as well as moveable objects such as garden furniture etc. can be blown over.
  • High waves on lakes, which wash over the banks or shores.
  • Electricity grid outages and/or failure of telephone networks for long periods of time and over widespread areas.
Recommended action Information on recommended action can be found here: What to do during strong winds
Description of measurement and prognostic values
  • Top wind speeds in low to medium-altitude areas: >140 km/h
  • Top wind speeds in higher-altitude areas (>1600 m above sea level): >200 km/h
Hazard category 4 (severe hazard)
Impact
  • Falling trees.
  • Damage to individual buildings and roofs.
  • Disruption or restriction of road, rail, water and air traffic.
  • Movement of securely anchored objects with a larger surface area, such as tents and scaffolding, as well as moveable objects such as garden furniture.
  • Electricity grid outages and/or failure of telephone networks.
Recommended action Information on recommended action can be found here: What to do during strong winds
Description of measurement and prognostic values
  • Top wind speeds in low to medium-altitude areas (incl. Foehn winds): 110-140 km/h
  • Top wind speeds in higher-altitude areas (>1600 m above sea level): 160-200 km/h
Hazard category 3 (significant hazard)
Impact
  • Falling branches and individual trees.
  • Damage to individual roofs.
  • Lightly anchored objects with larger surface areas, such as tents and scaffolding, can be blown over.
  • Some disruption to road, rail, water and air traffic.
  • Possible shutdown of ski lifts and cable cars.
Recommended action
Information on recommended action can be found here: What to do during strong winds
Description of measurement and prognostic values
  • Top wind speeds in low to medium-altitude areas (incl. Foehn winds): 90-110 km/h
  • Top wind speeds in higher-altitude areas (>1600 m above sea level): 130-160 km/h
Hazard category 2 (moderate hazard)
Impact
  • Surface turbulence hinders light aircraft from flying.
  • Waves higher than usual on lakes.
  • Toppling of objects inadequately secured or free-standing objects.
  • Breaking of smaller branches.
Recommended action Information on recommended action can be found here: What to do during strong winds
Description of measurement and prognostic values
  • Stormy winds in low and medium-altitude areas (incl. Foehn winds): 70-90 km/h
  • Stormy winds in higher altitude areas (>1600 m above sea level): 100-130 km/h