Is Kajaani or Siilinjärvi better for the northern lights?

Kajaani sits closer to the oval, at 61.2 degrees geomagnetic against 60.1. 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, Kajaani or Siilinjärvi?

Kajaani, with 17.0 hours of civil night on December 15 against 16.7 in Siilinjärvi.

What Kp do Kajaani and Siilinjärvi need?

By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Kajaani needs about Kp 3 and Siilinjärvi Kp 3 for the average oval edge to sit overhead.

When is it too light for aurora in Kajaani and Siilinjärvi?

Kajaani: May 17 to July 25. Siilinjärvi: May 22 to July 20.

Which is clearer, Kajaani or Siilinjärvi?

Kajaani, with 76% mean cloud in the months with 4 hours or more of civil night against 77% in Siilinjärvi (NASA POWER, 2001 to 2020).

Comparison

Kajaani vs Siilinjärvi for the northern lights

Answer

Kajaani sits 1.1 degrees higher on the IGRF-14 dipole, 61.2 against 60.1. By SWPC's oval-edge rule Kajaani needs about Kp 3 for the average edge to sit overhead and Siilinjärvi Kp 3. On the map Kajaani is also closer to the pole, by 1.1 degrees.

61.2° / 60.1°

dipole latitude

Side by side

Computed figures for both towns
Figure	Kajaani	Siilinjärvi
Dipole latitude	61.2°	60.1°
Kp for the oval edge overhead	Kp 3	Kp 3
Civil night, December 15	17.0 h	16.7 h
Dark-season days	269	277
Nights with no civil darkness	70	60
Dark-month cloud, NASA POWER	76%	77%
Solar midnight, December 15	00:04	00:04

Kajaani sits at 61.2 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 3. Siilinjärvi sits at 60.1 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 3.

Civil night month by month

On December 15 Kajaani has 17.0 hours of civil night and Siilinjärvi 16.7. Across the 15th of each month, Kajaani is darker in 4 months and Siilinjärvi in 5. The widest gap comes in May, when Siilinjärvi has 1.5 more hours.

Hours of civil night on the 15th of each month, 2026
Month	Kajaani	Siilinjärvi	Difference
January	16.2 h	15.9 h	+0.3 h
February	13.5 h	13.4 h	+0.1 h
March	10.5 h	10.6 h	-0.1 h
April	6.8 h	7.1 h	-0.3 h
May	1.1 h	2.6 h	-1.5 h
June	0.0 h	0.0 h	+0.0 h
July	0.0 h	0.0 h	+0.0 h
August	5.2 h	5.6 h	-0.4 h
September	9.2 h	9.3 h	-0.1 h
October	12.4 h	12.4 h	+0.0 h
November	15.4 h	15.2 h	+0.2 h
December	17.0 h	16.7 h	+0.3 h

Difference: Kajaani minus Siilinjärvi. Each figure links to that town's month page.

Season and midnight sun

Kajaani has no civil darkness from May 17 to July 25, 70 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 269 days. Siilinjärvi has no civil darkness from May 22 to July 20, 60 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 277 days.

Distance, cloud and time zones

The two towns are 127 km apart by great circle. In the dark months both average about 76% cloud in NASA POWER's 2001 to 2020 record. Kajaani's best month by civil night times clear sky is January. Siilinjärvi'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 Kajaani and Siilinjärvi, which carry the live OVATION cell.

Questions

Is Kajaani or Siilinjärvi better for the northern lights?: Kajaani sits closer to the oval, at 61.2 degrees geomagnetic against 60.1. 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, Kajaani or Siilinjärvi?: Kajaani, with 17.0 hours of civil night on December 15 against 16.7 in Siilinjärvi.
What Kp do Kajaani and Siilinjärvi need?: By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Kajaani needs about Kp 3 and Siilinjärvi Kp 3 for the average oval edge to sit overhead.
When is it too light for aurora in Kajaani and Siilinjärvi?: Kajaani: May 17 to July 25. Siilinjärvi: May 22 to July 20.
Which is clearer, Kajaani or Siilinjärvi?: Kajaani, with 76% mean cloud in the months with 4 hours or more of civil night against 77% in Siilinjärvi (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.