The far north is booked on a calendar, not on a map: the same three cities give opposite experiences six months apart, and the wrong month means not seeing the thing you travelled for. It should be said at once that these are also the most expensive destinations on this blog.
Tromsø: the rule is darkness
Tromsø lies over 300 kilometres inside the Arctic Circle, and its seasonality is absolute: the northern lights need long dark nights, so late September to early April. In summer the aurora is not seen — not because it is not there, but because between late May and late July the sun does not set at all.
Which opens the other possibility, equally a reason to come: the midnight sun, with excursions and cable car in full daylight at two in the morning. They are two different trips on the same plane ticket.
In winter there are husky sledges and encounters with Sami culture and reindeer, and between late autumn and early winter, in the nearby fjords, orcas and humpbacks are seen following the herring. All of it needs booking ahead. Budget: €130-200 a day in mid-season, €170-280 in high.
Bergen: the rain is part of the price
Bergen is the capital of the fjords and is almost certainly the rainiest place in Europe: not a meteorological detail but the character of the city, where rain is lived with rather than fought.
The season is June to August, when the light is nearly endless and all the fjord excursions run; May and September cost less and have fewer people, with the landscape either intensely green or in autumn colour.
Three things away from the Hanseatic wharf: the Ulriken cable car, climbing to 643 metres on the highest of Bergen's seven mountains and the start of the ridge walk; Troldhaugen, Edvard Grieg's villa-museum just outside town, with summer concerts in the music room; and the Fantoft stave church, originally from 1170, burnt down by arson in 1992 and rebuilt using medieval techniques.
Budget: €120-180 a day in mid-season.
Reykjavík: the dearest, and the most sociable
Reykjavík is the northernmost capital in the world and also the most expensive destination on this blog: €190-260 a day in mid-season, up to €260-380 in high. Know it in advance, because no trick makes it cheap.
One trick does exist, though, and it is also the best way to spend an afternoon: the city's geothermal pools cost 1,500 krónur a visit, with a ten-visit card at 7,000 — half price. It is the real Icelandic social ritual, not an attraction. The rule is strict and an attendant enforces it: shower naked with soap before putting on your swimsuit.
The best aurora spot near the city is the Grótta lighthouse, twenty minutes by bike, but it carries two constraints: the spit of land leading to it floods at high tide, and from 1 May to 15 July the area is closed for bird nesting.
The seasons are only apparently opposite to Tromsø's: June-August for near-continuous light and puffins, September-March for dark skies and the aurora.
How to decide
If the aim is the aurora: Tromsø or Reykjavík between October and March, knowing it is a weather lottery and that several nights are needed for a real chance. If the aim is fjords and trails: Bergen between May and September. If you want the light that never ends: Tromsø between late May and late July. In every case the budget is double that of central Europe — and the prices above are the verified ones, not optimistic estimates.