Saariselkä is one of the most reliable places in Europe to see the aurora. The skies are dark, the light pollution is almost nothing, and the season runs from late August (when nights become dark enough) through to early April. Peak frequency is generally September–October and February–March, when the sky is clearest.
You can chase the lights independently — walk five minutes out of the village and find a north-facing fell — or join a guided tour by snowmobile, sleigh, or minibus that takes groups to known dark-sky spots. Several operators run an aurora alarm service that wakes guests if the lights come out at night. Bring layers; you may be standing still in -20 °C for an hour or two.