Northern light (aurora borealis) mostly occurs at high latitudes (particularly around the 67-70th parallels). Northern Scandinavia and northern Finland are the best places to observe this in captivating phenomenon in Europe. In Northern Norway, the northern (or polar) light appears virtually every day, despite it can't be seen if the sky is cloudy. In southern Norway it occurs only occasionally.

The NL is created high in the atmosphere and is not restricted to any specific location. There is absolutly no need to go on an excursion or guided tour to see the lights. Darkness (city lights and full moon may obscure this rather weak light) and clear sky are the only prerequisits (a guide with a car can be helpful in finding good observation spots if there is none in the city). Winter darkness (polar night in December-January) allows nearly 24 hour observation, despite Aurora Borealis most likely appears at night time.

In the middle of the summer the lights can not be seen because of midnight sun or 24 hour daylight. NorthernLights season is generally going fromend of September to beginning of April.

More info:

Where and when to see Northern Lights