Northern lights may occur at any point during the hours of darkness and vary in duration. It has to be sufficient solar energy to create aurorae in the atmosphere combined with the  energy impacting the atmosphere at an angle that is suitable for our location. Clear skies or scattered clouds are required for the northern lights to be visible. There is no timetable. Northern lights are visible in Luleå from late August until the first days of April. During the rest of the year, the skies are too bright for the phenomenon to be visible. Read more about northern lights.