A forest fire is an uncontrolled fire occurring in nature. Sometimes, the forest fire is so large that it takes a long time for the fire fighting crews to gain control over the situation. This could result in massive destruction.
In Norway, an average of about 1100 forest fires occur each year. Most of these are small and relatively easy to control. Only two per cent of the registered forest fires in Norway are larger than 100 decares (100 000 m2).
Many forest fires are due to human activity
The number of forest fires varies from year to year, and quite a long time may elapse between forest fires that are considered to be large. Climatic conditions are the factor that has greatest impact on the extent of forest fires. The forest is most vulnerable in spring and summer seasons when there are long dry spells. Weather conditions such as precipitation and wind, as well as the layout of the terrain, are important factors in determining the size of the forest fire.
It is estimated that as many as nine out of ten forest fires are caused by humans, although the causes of a significant number of forest fires remain unknown. The most common cause of such fires is the use of open flames and disposable barbecue grills. Even a cigarette that is not properly extinguished can cause a forest fire. Some forest fires also start as a consequence of downed power lines, sparks from trains, sparks from edge trimmers along roadways or sparks from tools and forestry machinery doing work in the forest. Natural forest fires are due to lightning strikes.
In some cases, fires are set deliberately. The June 2008 forest fire in Froland in Aust Agder county is the largest and most serious recent example. This fire burned for 13 days and large crews from the fire service, the civil defence and the Armed Forces participated in the extinguishing efforts. At most, 15 helicopters were in the air to put out the fire. 77 residents in the community of Mykland had to be evacuated from their homes for a period of time. The fire affected an area of 27 000 decares, of which 19 000 decares were productive forests.
Building fires in or near forest land is prohibited during the period from 15 April to 15 September.