When is the polar night?

At the North Cape, the sun stays below the horizon for over two months, whereas in Tromsø, this phenomenon lasts for about six weeks. In Lofoten, the dark period is relatively brief, lasting just under four weeks. From Bodø and further south, the sun does make an appearance even in the heart of mid-winter, briefly illuminating the winter landscape around midday.
It is never entirely dark all the time.
Although the sun remains beneath the horizon, Northern Norway is not completely shrouded in darkness. On clear days, we can witness stunning sunset hues in the south, while the sky to the north takes on a deep midnight blue.
The “blue hour” is the most iconic time of the day.
Around 1–2 o’clock in the afternoon, the remaining light reflects off the blue sea and white snow, bathing the landscape in a glossy deep blue hue. This enchanting blue lingers as long as the snow blankets the ground and twilight persists. However, the blue hour occurs a few minutes later each day during winter as the sun gains strength.

Polar night only happens north of the Arctic Circle and during these periods:

Nordkapp November 18 - January 23
Hammerfest November 20 - January 21
Vardø November 21 - January 20
Tromsø November 25 - January 16
Harstad November 30 - January 11
Svolvær December 4 - January 7
Bodø December 15 - December 28