Inuvik sits more or less directly under the auroral oval, which makes it one of the best places on earth to see the northern lights. The season runs from late August (when the sun starts setting again) through to mid-April. The lights themselves are present most clear nights; the question is whether the sky is cloud-free and whether the magnetic activity is high enough to bring them to a strong display.
Operators in town run guided aurora tours by snowmobile, dog sled, or warm SUV — typically 10 p.m. to 2 a.m., with hot drinks. Late February and March are statistically the best months: long nights, less cloud than mid-winter, manageable temperatures (still around -25°C). You can also just stand outside in the dark — the town is small enough that light pollution is minimal a five-minute walk from the centre.