Northern lights in Tromsø in September
Possible, with patience — 28% of September nights offer a window.
The numbers behind it: September nights in Tromsø average about 7 dark hours, geomagnetic activity reaches local viewing levels on 97% of days, and 29% of nights offer at least one reasonably clear hour after dark.
The sky itself is the main obstacle in September — clouds spoil more nights than quiet solar activity does. Build in spare nights, and be ready to drive toward whatever gap the cloud forecast shows.
September also benefits from the equinox effect: around the equinoxes the Earth's magnetic field couples more efficiently with the solar wind (the Russell-McPherron effect), and 30 years of records show measurably more active days than in midwinter.
Numbers come from 1996–2025 Kp records (GFZ Potsdam) and 2015–2024 hourly cloud history for Tromsø itself — the full method is on the methodology page. Travelling soon? Check tonight's live Tromsø forecast.
September against the rest of the year
September elsewhere under the oval
- Yellowknife 59% of nights
- Fairbanks 36% of nights
- Kiruna 33% of nights
- Lofoten Islands 33% of nights
- Reykjavík 31% of nights
- Rovaniemi 29% of nights
- Abisko 22% of nights