As you explore the world of The Long Dark, you’ll notice auroras are often present in the sky, appearing and disappearing according to some unknown set of natural rules. Besides acting as a hauntingly beautiful reminder of what has transpired, the auroras also affect the world around you.
In Story mode, the aurora makes its first appearance during one of the earliest cutscenes. As the player wakes up following a plane crash, the aurora dances brilliantly across the sky. This initial, intensely bright aurora is hereafter referred to as the "First Flare."
After the First Flare knocks out most modern technology at the start of Episode 1, the aurora does not make another appearance until Episode 2, when the player blacks out near the Maintenance Yard after getting attacked by the Old Bear. From then on, auroras will keep making appearances seemingly at random.
The exact cause of the First Flare or its effects on electrical devices are not fully explained in the first two episodes of the story. However, the impact on electrical systems and the unusual brilliance of the aurora borealis are consistent with the potential effects of a powerful solar flare accompanied by a coronal mass ejection (CME) from the sun.
In Survival mode and most challenges, the aurora's appearance is uncommon and based on many factors, regardless of the region. It only appears during the night, sometimes well after sunset, and only when the weather is clear with no fog or snow.
When the aurora is present, electronics will come to life. Lights will flicker; computers will turn on, sometimes revealing information from before the Flare; radios in buildings or cars may be usable and, if they are turned on, will play classical music. In Wintermute, the elevator at the Carter Hydro Dam becomes operational.
In the Archivist challenge and other gameplay modes, a few intact screens in select locations will show readable messages called 'Buffer Memories'. The messages are usually lore-based and appear to be emails from people on Great Bear Island in the recent past.
The flashlight's battery can be recharged when the aurora is active. However, it will immediately die when the aurora ceases, rendering the flashlight useless until the next aurora.
Predators will be extremely aggressive and very dangerous during an aurora. They will ignore stimuli they normally fear, so flares, campfires, and similar items are not reliable deterrents. Predators will also lock on to the player from greater distances and will give chase for longer periods.
However, wolves and bears seem to fear the bright lights that come to life during the aurora. They will avoid street lamps, floodlights, and other bright electric lighting, much as wolves flee from campfires normally. Additionally, all wolves and bears have a green, iridescent glow to their fur that is visible from long distances. The carcasses of these predators retain the green glow, even after the aurora is over.
Coming into contact with certain electrified items, such as arcing cables, will severely injure the player, reducing their health by 50 points and giving a "burns" affliction. If entering an area only accessible through an electrically controlled door (which is required at least once during Wintermute), the player may be trapped inside if the aurora ends before the player exits. It may be many days until the next one allows the door to be opened.