Is Tromsø or Harstad better for the northern lights?

Tromsø sits closer to the oval, at 67.5 degrees geomagnetic against 67.1. Darkness, cloud and your dates decide the rest; the tables on this page show both towns month by month.

Which has longer nights in December, Tromsø or Harstad?

Tromsø, with 19.2 hours of civil night on December 15 against 18.7 in Harstad.

What Kp do Tromsø and Harstad need?

By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Tromsø needs about Kp 0 and Harstad Kp 0 for the average oval edge to sit overhead.

When is it too light for aurora in Tromsø and Harstad?

Tromsø: April 27 to August 14. Harstad: April 30 to August 12.

Which is clearer, Tromsø or Harstad?

Harstad, with 82% mean cloud in the months with 4 hours or more of civil night against 83% in Tromsø (NASA POWER, 2001 to 2020).

Comparison

Tromsø vs Harstad for the northern lights

Answer

Tromsø sits 0.4 degrees higher on the IGRF-14 dipole, 67.5 against 67.1. By SWPC's oval-edge rule Tromsø needs about Kp 0 for the average edge to sit overhead and Harstad Kp 0. On the map Tromsø is also closer to the pole, by 0.9 degrees.

67.5° / 67.1°

dipole latitude

Side by side

Computed figures for both towns
Figure	Tromsø	Harstad
Dipole latitude	67.5°	67.1°
Kp for the oval edge overhead	Kp 0	Kp 0
Civil night, December 15	19.2 h	18.7 h
Dark-season days	239	243
Nights with no civil darkness	110	105
Dark-month cloud, NASA POWER	83%	82%
Solar midnight, December 15	23:39	23:49

Tromsø sits at 67.5 degrees geomagnetic, inside SWPC's 60 to 75 degree band, where aurora can be seen on more than half of all nights. No storm is needed: by SWPC's rule the average oval edge is overhead at Kp 0. Harstad sits at 67.1 degrees geomagnetic, inside SWPC's 60 to 75 degree band, where aurora can be seen on more than half of all nights. No storm is needed: by SWPC's rule the average oval edge is overhead at Kp 0.

Civil night month by month

On December 15 Tromsø has 19.2 hours of civil night and Harstad 18.7. Across the 15th of each month, Tromsø is darker in 5 months and Harstad in 3. The widest gap comes in August, when Harstad has 1.7 more hours.

Hours of civil night on the 15th of each month, 2026
Month	Tromsø	Harstad	Difference
January	17.8 h	17.5 h	+0.3 h
February	14.0 h	13.9 h	+0.1 h
March	10.2 h	10.2 h	+0.0 h
April	4.8 h	5.3 h	-0.5 h
May	0.0 h	0.0 h	+0.0 h
June	0.0 h	0.0 h	+0.0 h
July	0.0 h	0.0 h	+0.0 h
August	0.6 h	2.3 h	-1.7 h
September	8.4 h	8.6 h	-0.2 h
October	12.7 h	12.6 h	+0.1 h
November	16.6 h	16.4 h	+0.2 h
December	19.2 h	18.7 h	+0.5 h

Difference: Tromsø minus Harstad. Each figure links to that town's month page.

Season and midnight sun

Tromsø has no civil darkness from April 27 to August 14, 110 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 239 days. Harstad has no civil darkness from April 30 to August 12, 105 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 243 days.

Distance, cloud and time zones

The two towns are 134 km apart by great circle. In the dark months both average about 82% cloud in NASA POWER's 2001 to 2020 record. Tromsø's best month by civil night times clear sky is January. Harstad's best month by civil night times clear sky is January. Time zones: Europe/Oslo and Europe/Oslo.

For tonight, open the live pages for Tromsø and Harstad, which carry the live OVATION cell.

Questions

Is Tromsø or Harstad better for the northern lights?: Tromsø sits closer to the oval, at 67.5 degrees geomagnetic against 67.1. Darkness, cloud and your dates decide the rest; the tables on this page show both towns month by month.
Which has longer nights in December, Tromsø or Harstad?: Tromsø, with 19.2 hours of civil night on December 15 against 18.7 in Harstad.
What Kp do Tromsø and Harstad need?: By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Tromsø needs about Kp 0 and Harstad Kp 0 for the average oval edge to sit overhead.
When is it too light for aurora in Tromsø and Harstad?: Tromsø: April 27 to August 14. Harstad: April 30 to August 12.
Which is clearer, Tromsø or Harstad?: Harstad, with 82% mean cloud in the months with 4 hours or more of civil night against 83% in Tromsø (NASA POWER, 2001 to 2020).

Sources and verification

IGRF-14 coefficients, NOAA NCEIhttps://www.ngdc.noaa.gov/IAGA/vmod/coeffs/igrf14coeffs.txt
SunCalchttps://github.com/mourner/suncalc
GeoNameshttps://www.geonames.org/export/
NASA POWER climatologyhttps://power.larc.nasa.gov/docs/services/api/temporal/climatology/
NOAA SWPC, Tips on viewing the aurorahttps://www.spaceweather.gov/content/tips-viewing-aurora

Quoted figures last checked against their sources on 2026-09-30; next review 2026-12-31. Computed figures come from SunCalc and the IGRF-14 dipole as described in the methodology. Every quote is listed in the sources ledger.