Worth Going Out

Northern lights in Tromsø in September

Norway. Figures for September 2027, calculated by us. Times are local.

Go

Yes, with shorter nights. In mid-September the sky is dark enough for the aurora from about 21:48 to 03:31, 5.5 hours a night.

Darkness through the month

1 September: no real darkness.
15 September: 5.5 hours.
End of September: 8 hours. The nights are getting longer 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 September 2027

Full Moon: 15 September 2027. A bright Moon makes the aurora look fainter, though it is still there.
New Moon: 30 September 2027. The week around it has the darkest skies.

What to expect

The aurora appears only on active nights, and only where it is clear. Plan several nights and check the forecast each day: how to read it.
NOAA’s Space Weather Prediction Center names the weeks around the equinoxes, in March and September, as the best season for aurora watching.
On the coast the weather changes quickly. Tours often drive inland to look for gaps in the cloud, so a guided night can help even if you have a car.

A green ring of northern lights over a snowy mountain under a cloudy, moonlit sky — The northern lights in Tromsø, Norway. Photo: Andi Gentsch, CC BY-SA 2.0, 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.

Tromsø: 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.