Finland is one of the best inhabited regions in the world for viewing northern lights, i.e. auroras.
Finland is on the southern rim of the auroral oval. The probability for seeing auroras is best in the northernmost part of the country, i.e. in Lapland. During geomagnetic storms the auroral oval expands southward and then auroras are seen also in Central and Southern Finland.
The statistical probability for seeing auroras during a dark and cloudless night is approximately:
- at Kilpisjärvi: 75 % of nights
- in central Lapland (e.g. ski resorts Ylläs, Levi, Saariselkä): roughly 50 % of nights
- in the central part of Finland (e.g. Oulu, Kuusamo): roughly 25 % of nights
- on the south coast (e.g. Helsinki, Turku): once in a month on average.
The typical time for auroral displays is at midnight, and a couple of hours before and after. However, auroras may occurr randomly anytime when the sky is dark enough for seeing them.
Auroras occurr quite evenly throughout the year, although the rate is slightly higher during spring and autumn than during winter and summer. However, in summer the nights are generally too light for seeing the auroras. Especially so in Lapland, where the sun does not set at all during a period around midsummer. Considering also the weather, the best time for seeing auroras in Northern Finland is in March and early April.
The solar activity, which varies with the 11-year sunspot cycle, also affects the frequency of auroras. The amount of large auroral displays tends to follow the amount of sunspots with a lag of a couple of years. The previous sunspot maximum was in 2014, so the winters of 2015–2017 are excellent time for auroras. This solar cycle effect is most pronounced in Southern Finland. In Lapland auroras are quite common always, even during solar minimum.
Tips for aurora watching
Find a dark, open place preferably far away from town lights. As auroras are most often seen on the northern sky, try to find an unrestricted view at least toward the northern horizon.
Optimal weather for watching auroras, dark and cloudless night, is practically always cold in Finland. Dress very warmly.
Lying on a mattress may be a more comfortable way to gaze up than bending your neck backward for lengthy times.