Is Saint Petersburg or Lahti better for the northern lights?

Lahti sits closer to the oval, at 58.4 degrees geomagnetic against 56.7. 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, Saint Petersburg or Lahti?

Lahti, with 16.2 hours of civil night on December 15 against 16.0 in Saint Petersburg.

What Kp do Saint Petersburg and Lahti need?

By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Saint Petersburg needs about Kp 5 and Lahti Kp 4 for the average oval edge to sit overhead.

When is it too light for aurora in Saint Petersburg and Lahti?

Saint Petersburg: never, every night has civil darkness. Lahti: June 5 to July 6.

Which is clearer, Saint Petersburg or Lahti?

Lahti, with 74% mean cloud in the months with 4 hours or more of civil night against 75% in Saint Petersburg (NASA POWER, 2001 to 2020).

Comparison

Saint Petersburg vs Lahti for the northern lights

Answer

Lahti sits 1.7 degrees higher on the IGRF-14 dipole, 58.4 against 56.7. By SWPC's oval-edge rule Lahti needs about Kp 4 for the average edge to sit overhead and Saint Petersburg Kp 5. On the map Lahti is also closer to the pole, by 1.0 degrees.

56.7° / 58.4°

dipole latitude

Side by side

Computed figures for both towns
Figure	Saint Petersburg	Lahti
Dipole latitude	56.7°	58.4°
Kp for the oval edge overhead	Kp 5	Kp 4
Civil night, December 15	16.0 h	16.2 h
Dark-season days	301	291
Nights with no civil darkness	0	32
Dark-month cloud, NASA POWER	75%	74%
Solar midnight, December 15	00:54	00:12

Saint Petersburg sits at 56.7 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 5, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less. Lahti sits at 58.4 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 4, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less.

Civil night month by month

On December 15 Saint Petersburg has 16.0 hours of civil night and Lahti 16.2. Across the 15th of each month, Saint Petersburg is darker in 6 months and Lahti in 3. The widest gap comes in June, when Saint Petersburg has 1.0 more hours.

Hours of civil night on the 15th of each month, 2026
Month	Saint Petersburg	Lahti	Difference
January	15.3 h	15.5 h	-0.2 h
February	13.2 h	13.2 h	+0.0 h
March	10.7 h	10.7 h	+0.0 h
April	7.7 h	7.5 h	+0.2 h
May	4.5 h	4.0 h	+0.5 h
June	1.0 h	0.0 h	+1.0 h
July	3.1 h	2.3 h	+0.8 h
August	6.5 h	6.3 h	+0.2 h
September	9.6 h	9.5 h	+0.1 h
October	12.3 h	12.3 h	+0.0 h
November	14.7 h	14.8 h	-0.1 h
December	16.0 h	16.2 h	-0.2 h

Difference: Saint Petersburg minus Lahti. Each figure links to that town's month page.

Season and midnight sun

Saint Petersburg has some civil darkness every night of 2026, and its dark season, 4 or more evening hours of civil night, lasts 301 days. Lahti has no civil darkness from June 5 to July 6, 32 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 291 days.

Distance, cloud and time zones

The two towns are 280 km apart by great circle. In the dark months both average about 75% cloud in NASA POWER's 2001 to 2020 record. Saint Petersburg's best month by civil night times clear sky is March. Lahti's best month by civil night times clear sky is March. Time zones: Europe/Moscow and Europe/Helsinki.

For tonight, open the live pages for Saint Petersburg and Lahti, which carry the live OVATION cell.

Questions

Is Saint Petersburg or Lahti better for the northern lights?: Lahti sits closer to the oval, at 58.4 degrees geomagnetic against 56.7. 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, Saint Petersburg or Lahti?: Lahti, with 16.2 hours of civil night on December 15 against 16.0 in Saint Petersburg.
What Kp do Saint Petersburg and Lahti need?: By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Saint Petersburg needs about Kp 5 and Lahti Kp 4 for the average oval edge to sit overhead.
When is it too light for aurora in Saint Petersburg and Lahti?: Saint Petersburg: never, every night has civil darkness. Lahti: June 5 to July 6.
Which is clearer, Saint Petersburg or Lahti?: Lahti, with 74% mean cloud in the months with 4 hours or more of civil night against 75% in Saint Petersburg (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.