menu

jump links

selected

Content

Danger levels forest fire

Given that only 10 percent of forest fires have a natural cause (lightning), it can be assumed that 90 percent of such fires are caused by inappropriate human behaviour (discarding glowing cigarette butts, barbecue fires that are not completely extinguished etc.). Forest fire risk usually occurs during and after winters with little snow, after long periods of dry weather and during summer heatwaves, and especially if such conditions coincide with strong winds (e.g. foehn). All these factors can severely dehydrate trees, shrubs and the forest floor.

Forest fires in Switzerland most often affect small areas. Besides the valleys that are regularly exposed to the foehn, the primarily endangered regions are Valais, Graub√ľnden and Ticino. People are seldom endangered by forest fires because Swiss legislation prohibits the construction of housing in forests.

The forest fire risk indicates the probability of a forest fire occurring. It can be exacerbated e.g. by people engaging in leisure activities, so that action needs to be taken even if the danger of a forest fire is low.

Danger level 5 (very high)
Description of measured and forecast values
  • Outbreak: Fires can start at any time.
  • Rate of spread: Very high over a long period.
Effects
  • Characteristics: Very intense burning, extensive crown fires, long-distance spotting.
  • Fire-fighting: Forest fire is virtually impossible to extinguish.
Behaviour
  • Do not make any fires outdoors.
  • Follow the instructions and observe the fire bans imposed by the local authorities.
Danger level 4 (high)
Description of measured and forecast values
  • Outbreak: Burning matches, flying sparks from barbecue fires and lightning will very probably ignite a fire.
  • Rate of spread: High, including in forests.
Effects
  • Characteristics: Intense surface fires can ignite the crowns of individual trees, spotting is possible, burning topsoil.
  • Fire-fighting: Forest fire is difficult to extinguish and commands extensive resources.
Behaviour
  • As a general rule, do not make any fires outdoors.
  • Permanent fire places (concreted base) in locations designated by the authorities can be used with the utmost caution.
  • Do not make fires in strong winds.
  • Follow the instructions (observe the fire bans) of the local authorities.
Danger level 3 (considerable)
Description of mesured and forecast values
  • Outbreak: Burning matches and flying sparks from barbecue fires can ignite a fire. Lightning can also trigger widespread fires.
  • Rate of spread: High in open terrain, medium in the forest.
Effects
  • Characteristics. Topsoil is partly burnt, individual crown fires are possible.
  • Fire-fighting: Forest fire can be extinguished only by experts using modern equipment.
Behaviour
  • Light barbecue fires only in existing fire places.
  • Always watch the fire and immediately extinguish stray sparks.
  • Follow the instructions of the local authorities.
Danger level 2 (moderate)
Description of measured and forecast values
  • Outbreak: Local fires can start spontaneously. Lightning only rarely causes a conflagration.
  • Rate of spread: Slow to medium.
Effect
  • Characteristics: Surface or crawling fires, crowns of trees are rarely affected, topsoil is burnt a little or not at all.
  • Fire-fighting: Forest fire is ordinarily easy to extinguish.
Behaviour
  • Do not carelessly discard cigarettes, tobacco products or lighters.
  • Always watch barbecue fires and immediately extinguish stray sparks.
Danger level 1 (low or none)
Description of measured and forecast values

 
  • Outbreak: Small fires cannot be entirely ruled out, but require a high energy input. Lightning hardly ever causes a fire.
  • Rate of spread: Generally slow.
Effects
  • Characteristics: Surface or crawling fires, crowns of trees are not affected, topsoil does not burn.
  • Fire-fighting: Forest fire is easy to extinguish.
Behaviour
  • Do not carelessly discard cigarettes, tobacco products or lighters.

Kontextspalte