Hello and thanks for the question.
All I know of it is what was left written from before the 1800’s but the Årsgång (Year Walk) should be done on one of the following nights:
Winter Solstice, Julnatten (Christmas night), New Year’s Eve (first full moon after Jul), Twelfth night, Lucianatten (Lucia’s night) or Midsummer Solstice.
The process is to lock oneself away in a dark room. You must not see light or fire for the whole day from when you wake until you begin Årsgång. You must also not speak or make noise (such as laughing) during this time. You would also require to be nearby a cemetery.
As the clock tower of the church strikes midnight you are permitted to leave your dark room and venture forth to make your way towards the church. On the way you may encounter all manner of supernatural creatures from folklore and face challenges that will test your mind, faith and may even risk physical harm.
If/when you arrive at the church you may see several different things.
- If you see upturned graves then it means a plague will come.
- If you see Dverger (Dwarfs), Nisse (Gnomes) or Avler (Elves) with a hay cart or wheat then it means a good harvest is coming.
- If you see armed men then it means a war is coming.
There are more but I do not have a full list at hand.
If someone was brave enough to perform the Årsgång for seven consecutive years, on your final Year Walk you would meet a man on horseback with a rune engraved stick in his mouth. If you can snatch this stick then you will gain the power of prophecy forever. You will have knowledge of all secret things and be able to see the future without ever having to go through Årsgång again.
As for safety and if you should do it. I do not know. I could not say for sure it is safe and it is not something I would advise to take a risk on. Maybe it is just superstitious nonsense but why take the risk I say!
Års (!) og fred!