Rovaniemi or Tromsø for the lights: dark hours and cloud, scored

On dark hours Tromsø wins every month from November to February, by between 0.4 and 1.5 hours a night, and the margin is largest in December when Tromsø has 19.5 dark hours to Rovaniemi's 18.0. On cloud, the only national figure that could be read today is Finnish and it is not flattering: the Finnish Meteorological Institute says that in autumn and winter "about 65% to 85% of the sky is then covered in cloud" and that clear days are fewest "in November and December". MET Norway's equivalent for Tromsø could not be read. So the score below is finished for darkness and unfinished for cloud, and it says so rather than filling the gap with a number from a travel site.

#Dark hours, computed

NOAA solar position equations for Rovaniemi (66.50° N, 25.73° E), Tromsø (69.65° N, 18.96° E) and Reykjavík (64.15° N, 21.94° W), on the 15th of each month, counting the hours the sun is more than 6° below the horizon, the end of civil twilight. Local civil time at each place; the count is per calendar day.

Three things the table says. The spread between the three places never exceeds 2.3 hours, and in September, October and March it is under half an hour. Darkness is not what separates them. By April Tromsø has the least dark of the three, because high latitude cuts both ways. And Reykjavík is within 1.3 hours of Rovaniemi in every month, which is the number to remember when someone says Iceland is too far south for the lights; it is inside the auroral zone and it is dark enough.

#Cloud, as published

The Finnish Meteorological Institute's "Climate elements" page, read 1 November 2026, gives the national picture in words rather than station tables: cloud cover "is especially abundant in Finland in autumn and winter", 65 to 85 per cent of the sky; cloudiness increases from the north-west towards the south-east; clear days are most frequent in May and June and least in November and December; and annual sunshine is lowest, about 1,300 hours, in eastern Lapland. Rovaniemi is western Lapland, on the better side of that gradient, and January and February are drier and clearer than November, which is why the Lapland ledger starts in February and not in December. The institute's station normals for 1991–2020 are behind a data-request page and were not pulled.

For Tromsø the honest line is shorter. seklima.met.no and klimaservicesenter.no, the two MET Norway portals that hold cloud and sunshine normals, load as script applications and returned no text today; yr.no's statistics table for Tromsø carries temperature and precipitation only, with a normal of 94 mm for November, 110 for December, 108 for January and 97 for February, which describes a wet coast but is not a cloud figure. The Norwegian cloud cell stays empty. Reykjavík's was not checked for this post.

#The score

Two terms, each out of five, and a total only where both exist.

Darkness: one point for every hour above 13 dark hours on 15 January, capped at five. Rovaniemi 17.0 hours, 4.0 points. Tromsø 18.1 hours, 5.0 points. Reykjavík 16.4 hours, 3.4 points.

Cloud: five points for a published winter clear-sky share above 50 per cent, scaled down to zero at 15 per cent, from the national service's own figure. Rovaniemi: FMI's 65 to 85 per cent cloud gives a 15 to 35 per cent clear share, 0.0 to 2.9 points, call it 1.5 with the range shown. Tromsø: no figure read, blank. Reykjavík: not checked, blank.

A score that cannot be totalled still shows where the decision sits: in the cloud column, which the national weather services publish and travel pages guess. The ledger's answer to the missing column is the route itself, three bases under three skies.

#What this does to the Iceland decision

Reykjavík's 16.4 dark hours in January are 0.6 short of Rovaniemi's and 1.7 short of Tromsø's. Nobody stays awake for 16 hours of dark; the lights need two or three clear ones. The Iceland decision is therefore made on the cloud column and on the days, not the nights: the south coast ledger has pools, waterfalls and an ice cave for the cloudy afternoons and a hire car at the airport, and the Lapland ledger has three chances at a clear sky and a long cold drive. When the Norwegian cloud normals can be read, this post will carry them and the score will total.

#Sources

• NOAA Global Monitoring Laboratory, solar calculator equations, computed here for the three bases on 1 November 2026: https://gml.noaa.gov/grad/solcalc/calcdetails.html
• Finnish Meteorological Institute, climate elements (cloud cover, clear days, sunshine), read 1 November 2026: https://en.ilmatieteenlaitos.fi/climate-elements
• Finnish Meteorological Institute, normal periods and climate statistics (station normals by request), read 1 November 2026: https://en.ilmatieteenlaitos.fi/normal-period
• yr.no, Tromsø statistics (temperature and precipitation normals; no cloud), read 1 November 2026: https://www.yr.no/en/statistics/table/1-305409/Norway/Troms/Troms%C3%B8/Troms%C3%B8
• MET Norway, seklima (script application, no text returned 1 November 2026): https://seklima.met.no/
• Norsk klimaservicesenter, klimanormaler (script application, no text returned 1 November 2026): https://klimaservicesenter.no/kss/klimanormaler
• The Lapland aurora ledger and the Iceland or Lapland comparison on this site: /journeys/lapland-aurora-week-rovaniemi-tromso