Daylight in Finland

City	Latitude	Longest day	Shortest day	Polar night	Midnight sun
Utsjoki	69.9°N	24h 00m	no sunrise	yes	yes
Kilpisjärvi	69.0°N	24h 00m	no sunrise	yes	yes
Saariselkä	68.4°N	24h 00m	no sunrise	yes	yes
Levi	67.8°N	24h 00m	no sunrise	yes	yes
Rovaniemi	66.5°N	24h 00m	2h 14m	no	yes
Oulu	65.0°N	22h 02m	3h 34m	no	no
Tampere	61.5°N	19h 30m	5h 20m	no	no
Turku	60.5°N	19h 04m	5h 44m	no	no
Helsinki	60.2°N	18h 56m	5h 48m	no	no

The longest and shortest days are sampled on the 1st and 15th of each month and on the solstices, so a figure can be a minute or two off the true extreme. The polar night and midnight sun columns are not approximations: they are whether the sun fails to rise or fails to set at all on a sampled date.

Rovaniemi is the interesting one, and the table above says something most guides get wrong: it has the midnight sun and no polar night. The Arctic Circle is defined as the latitude where the sun just fails to rise at the winter solstice, but that definition ignores refraction — and the atmosphere bends enough light over the horizon that the sun does clear it here. Rovaniemi gets two hours and fourteen minutes of daylight on the solstice. In June the same effect works the other way and helps, so the midnight sun is real. The Circle gives you one of the two, not both. The first latitude on this list with genuine polar night is Levi, at 67.8°N.

For the aurora, daylight is not the number that matters — astronomical darkness is, meaning the sun more than 18° below the horizon. Rovaniemi has no astronomical darkness at all from late May to mid-July, even though the sun does set. That is why the aurora pages say "too light" in June on nights when the sun goes down at half past midnight.