Norway

Norway makes a trade no other country here makes. The North Atlantic Drift carries warm water the length of this coast and keeps the ports ice-free to 71°N, which produces the largest temperature anomaly on earth: a January night in Tromsø is around minus five where Yellowknife and Fairbanks are at minus thirty. That is a genuine gift, and it arrives with a bill. Warm sea means moisture, and moisture means cloud.

You can measure the bill. Across eleven seasons of reanalysis, counting nights with at least two hours of cloud cover at or below 50% in the hours tours actually run, Tromsø gets a usable sky on 25.4% of season nights. That is twelfth of the fourteen destinations on this site, and last of Norway's three. Bodø, two hundred kilometres south and a fraction of the market, gets 32.9%. Alta, further north and up a long fjord, gets 29.3%. Both beat Tromsø in every single month of the season.

That is not an argument against Tromsø, and it explains something about it. With 74 departures competing in one town and the worst sky of the three, the operators there have built the most sophisticated escape machinery in the business: working radii of 200, 300 and 350 kilometres, guide networks trading cloud reports by phone all evening, and a willingness to cross into Finland. A fixed-point statistic cannot capture that, and it understates what a chase actually achieves. Tromsø has the worst sky and the best tools for getting out from under it, and the price of those tools is why a seat there costs what it does.