Northern lights in Rovaniemi in May

Finland. Figures for May 2027, calculated by us. Times are local.

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No: it never gets dark enough. In mid-May the Sun never gets more than 12° below the horizon, so the sky stays too bright to see the aurora, however active it is.

Darkness through the month

1 May: no real darkness.
15 May: no real darkness.
End of May: no real darkness. The nights are about the same through the month.

“Dark” here means the Sun is more than 12° below the horizon. Faint aurora needs a darker sky; a strong display can show earlier in the evening.

The Moon in May 2027

New Moon: 6 May 2027. The week around it has the darkest skies.
Full Moon: 20 May 2027. A bright Moon makes the aurora look fainter, though it is still there.

What to expect

Come back between September and March, when there is real darkness.
The town is bright at night. Go a few kilometres out, to a lake shore or a clearing, for darker skies.

A swirl of green northern lights above snow-covered pine trees — The northern lights above Lake Inari, Finnish Lapland, March 2018. Photo: Ximonic (Simo Räsänen), CC BY-SA 4.0, via Wikimedia Commons.

Get a note when it is worth going out

A short email before an eclipse, a strong meteor shower or a dark week worth planning for. No more than a few a month.

Rovaniemi: the whole year. All northern lights destinations.

Sources

Darkness, sunrise and Moon phases: our calculation, Astronomy Engine 2.1.19 (MIT licence). How we worked it out.
NOAA Space Weather Prediction Center, Tips on viewing the aurora.