Forest fire danger
What the danger index is, what the levels mean and when the danger is highest.
The forest fire danger tells you how easily a fire can start and how fast it can spread. Here we explain the levels and when in the year and the day the danger is highest.
What is the forest fire danger index?
In June 2021 the Norwegian Meteorological Institute and the Directorate for Civil Protection (DSB) introduced a daily forest fire danger index for all of Norway. It is based on the Canadian Fire Weather Index, adapted to Norwegian conditions.
The index is calculated from the weather, including temperature, humidity, precipitation, wind and snow.
What do the danger levels mean?
Low danger (green): low risk, the ground is usually damp. Some danger (yellow): fires can start until it rains. Danger (orange): high probability of fire, and a fire may be hard to control. High danger (light red): very high probability of fire.
High danger also comes in dark red: then an already difficult situation can get worse, for example if the wind picks up.
Is the forest fire danger a warning?
No. The index is one of several tools the meteorologists use. When it has been dry for a long time, the Norwegian Meteorological Institute issues separate forest fire warnings at yellow (moderate) or orange (considerable) level. The warning is an overall assessment, and warnings from local authorities always take precedence over the index.
Always follow the warnings and the advice of the municipality and the fire service.
When in the year and the day is the danger highest?
Usually in spring and summer. Right after the snow melts, last year's grass and heather are dead and dry, and a few dry days can be enough for them to burn easily. For the forest itself to burn, it usually has to be dry for several weeks. A long, dry autumn can also bring danger.
Over the day, the danger is highest in the afternoon and lowest late at night.
Why are there so many grass and heather fires in spring?
After the snow melts, last year's withered grass and heather lie on top, and they dry quickly. It takes only a few days of dry weather before the danger of grass and heather fires can be high, while trees only burn once it has been dry for long enough.
In 2025 there were 1,117 fires in open land and farmland in Norway: 468 in forest and open land and 649 in grass and farmland. More than half happened from March to May. Careless campfires and the use of open fire are the most common causes.
Where in Norway is the danger highest?
In the most forested parts of Eastern and Southern Norway. Pine forest burns more easily than spruce forest, because spruce forest holds on to moisture better.
Winters without snow can bring as much danger of grass and heather fires as spring does. The fires in Flatanger and on Frøya in January 2014 are examples.