Where can the avalanche occur, and how far can they travel? If you are planning a winter summit tour, you must be able to recognise and avoid avalanche terrain. This guide outlines the level of avalanche knowledge required for travel in simple, challenging, and complex terrain.
Published: April 20, 2026 Written by:
Håvard Engen, Fjellsportgruppa i Trondhjems Turistforening
Inspiration
In this article, you will find an overview of the recommended competence for each terrain class, along with key concepts you need to understand before travelling off marked routes in winter.
The avalanches are the most dangerous of these and mainly break loose in terrain above 30 degrees. These are called loosening areasand this is what we define as steep terrain. The avalanches continue down into gentler or completely flat terrain in outlet areas.
Together, the loosening and outlet areas make up what we define as avalanche terrain. Identifying both of these on the map and in the terrain is a minimum skill you need to have to travel off marked trails in the mountains in winter.
Avalanche school and steepness map
A good start is to read about this at the Avalanche School on Varsom.no and a good continuation is to take an avalanche course in DNT.
Here you will find steepness maps online. In addition, you must be able to use a map, compass and GPS so that you always know where you are and in which direction you can walk safely even in bad weather and visibility.
The terrain can also be referred to as 1: Simple, 2: Challenging, or 3: Complex, based on the distribution of loosening and outlet areas and terrain traps. See the distribution of these different classes on the map from NVE here and read more about each of them below.
Trips in simple terrain require basic avalanche knowledge
Simple terrain is clear and only occasionally has steep sections so that it is possible to completely avoid loosening areas, only in exceptional cases do you need to cross outlet areas, and there are few terrain traps. For most skiers in the mountains, this is the favorite terrain that offers an incredible number of opportunities both on backcountry skis and backcountry skiing.
As mentioned above, you must still be able to identify the steepness around you so that you can avoid the avalanche terrain. Recommended group size is from 1 to 16 on tour.
Even if you do not intend to move into the avalanche terrain, it is a good habit to check the regional avalanche forecast on Varsom.no, it will give you information about the snow conditions and mountain weather and useful knowledge if you later want to seek out more demanding terrain. Even here, there will be terrain around 30 degrees that you can choose to seek out or avoid.
You can learn the basic avalanche knowledge through experiences on trips with knowledgeable skiers, read about avalanches in books and online and to take a one-day course avalanches or even better a basic course avalanche quality assured by NF - Norwegian Mountain Sports Forum. A Nordic basic course usually runs from Friday evening to Sunday, while a similar alpine course lasts one more day starting on Thursday evening.
Trips in challenging terrain require advanced avalanche knowledge
On the next level, we find the hikes in challenging terrain. Here you get the avalanche terrain closer to you and more terrain traps and you have to make active choices to avoid these. At the same time, you can also choose to walk or drive steeply, but this requires that you also relate to the stability of the snow through the use of the avalanche warning on the varsom.no and the traffic advice there and continuous collection of information from the snow as you go.
In any case, remember that the avalanche warning applies to an entire region and that there may be local variations that the forecast is unable to capture.
In order for the avalanche forecast and traffic advice to make sense, you must learn what they mean through the avalanche school at varsom.no and to attend an avalanche course. You will receive training in this at an NF basic course Nordic or alpine. To become even better at making your own assessments, you can also build on with NF advanced courses.
Recommended group size is from 2 to 8 on tour.
Hiking in complex terrain requires advanced avalanche knowledge
The third and most demanding terrain class is called complex terrain. Here, the terrain is both steep and confusing with many terrain traps and few or no safe areas outside avalanche terrain. Here you also start from the avalanche forecast and the traffic advice on varsom.no, at the same time you must be able to make challenging, independent assessments of the avalanche risk where you are and where you are going.
In addition, it will require a lot from everyone who is on the trip both in terms of terrain understanding, skiing technique and not least how you communicate and make decisions. You must therefore have walked the path via learning the avalanche and skiing subject in easier terrain classes before approaching complex terrain.
We recommend that before you set off in complex terrain as a minimum, you have completed an NF advanced course and gained a lot of practical experience in less demanding terrain than this.
