Each season above the Arctic Circle is a different world: ruska autumn colour, kaamos polar night, midnight sun and the spring snow window. When to come.
When is the kaamos polar night in Lapland? Kaamos, the polar night, falls roughly from late November to mid-January. The further north you go, the longer it lasts: in Utsjoki, Finland's northernmost municipality, the sun stays below the horizon for about 52 days. It is not pitch dark, though: snow reflects a long blue-and-violet twilight through the middle of each day, and the long nights give plenty of aurora time.
When does the midnight sun happen in Lapland? On the Arctic Circle at Rovaniemi the sun stays up for about a month around midsummer, and the further north you go, the longer it lasts. In Utsjoki the midnight sun runs from mid-May to late July, over 70 days. Above the Arctic Circle you can hike, fish or paddle at midnight in full daylight.
When is ruska (autumn colour) in Lapland? Ruska moves from north to south in late August and September. The northernmost fells around Utsjoki and Kilpisjärvi turn first, around the turn of the month; Inari and Saariselkä usually peak in the first half of September; Pallas, Levi and Pyhä follow in mid-September; and Riisitunturi and Oulanka hold on into the third or fourth week. The timing varies from year to year.
What is the best season to visit Lapland? It depends on what you came for. Choose the dark season (late August to early April) for aurora, with March often the best month; late winter and spring (March–April) for snow with long, bright days; the midnight sun (June–July) for hiking and paddling; and ruska (September) for autumn colour. Match the season to the trip, not the other way round.
Does it get dark during the midnight sun? No. Above the Arctic Circle the sun does not set at midsummer, so there is no real night for several weeks, only a soft dip in light around the small hours. This means aurora viewing is impossible in June and July; the sky simply never gets dark enough.