Is Rovaniemi or Kemi better for the northern lights?

Rovaniemi sits closer to the oval, at 63.6 degrees geomagnetic against 63.1. 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, Rovaniemi or Kemi?

Rovaniemi, with 17.7 hours of civil night on December 15 against 17.5 in Kemi.

What Kp do Rovaniemi and Kemi need?

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

When is it too light for aurora in Rovaniemi and Kemi?

Rovaniemi: May 8 to August 4. Kemi: May 10 to August 1.

Which is clearer, Rovaniemi or Kemi?

Rovaniemi, with 76% mean cloud in the months with 4 hours or more of civil night against 76% in Kemi (NASA POWER, 2001 to 2020).

Comparison

Rovaniemi vs Kemi for the northern lights

Answer

Rovaniemi sits 0.6 degrees higher on the IGRF-14 dipole, 63.6 against 63.1. By SWPC's oval-edge rule Rovaniemi needs about Kp 2 for the average edge to sit overhead and Kemi Kp 2. On the map Rovaniemi is also closer to the pole, by 0.8 degrees.

63.6° / 63.1°

dipole latitude

Side by side

Computed figures for both towns
Figure	Rovaniemi	Kemi
Dipole latitude	63.6°	63.1°
Kp for the oval edge overhead	Kp 2	Kp 2
Civil night, December 15	17.7 h	17.5 h
Dark-season days	255	260
Nights with no civil darkness	89	84
Dark-month cloud, NASA POWER	76%	76%
Solar midnight, December 15	00:12	00:17

Rovaniemi sits at 63.6 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 2. Kemi sits at 63.1 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 2.

Civil night month by month

On December 15 Rovaniemi has 17.7 hours of civil night and Kemi 17.5. Across the 15th of each month, Rovaniemi is darker in 4 months and Kemi in 3. The widest gap comes in August, when Kemi has 0.4 more hours.

Hours of civil night on the 15th of each month, 2026
Month	Rovaniemi	Kemi	Difference
January	16.7 h	16.5 h	+0.2 h
February	13.7 h	13.6 h	+0.1 h
March	10.4 h	10.4 h	+0.0 h
April	6.1 h	6.4 h	-0.3 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	4.1 h	4.5 h	-0.4 h
September	8.9 h	9.0 h	-0.1 h
October	12.5 h	12.5 h	+0.0 h
November	15.8 h	15.7 h	+0.1 h
December	17.7 h	17.5 h	+0.2 h

Difference: Rovaniemi minus Kemi. Each figure links to that town's month page.

Season and midnight sun

Rovaniemi has no civil darkness from May 8 to August 4, 89 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 255 days. Kemi has no civil darkness from May 10 to August 1, 84 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 260 days.

Distance, cloud and time zones

The two towns are 99 km apart by great circle. In the dark months both average about 76% cloud in NASA POWER's 2001 to 2020 record. Rovaniemi's best month by civil night times clear sky is January. Kemi's best month by civil night times clear sky is January. Time zones: Europe/Helsinki and Europe/Helsinki.

For tonight, open the live pages for Rovaniemi and Kemi, which carry the live OVATION cell.

Questions

Is Rovaniemi or Kemi better for the northern lights?: Rovaniemi sits closer to the oval, at 63.6 degrees geomagnetic against 63.1. 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, Rovaniemi or Kemi?: Rovaniemi, with 17.7 hours of civil night on December 15 against 17.5 in Kemi.
What Kp do Rovaniemi and Kemi need?: By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Rovaniemi needs about Kp 2 and Kemi Kp 2 for the average oval edge to sit overhead.
When is it too light for aurora in Rovaniemi and Kemi?: Rovaniemi: May 8 to August 4. Kemi: May 10 to August 1.
Which is clearer, Rovaniemi or Kemi?: Rovaniemi, with 76% mean cloud in the months with 4 hours or more of civil night against 76% in Kemi (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.