Comparison
Turku vs Seinäjoki for the northern lights
Answer
Side by side
| Figure | Turku | Seinäjoki |
|---|---|---|
| Dipole latitude | 58.4° | 60.5° |
| Kp for the oval edge overhead | Kp 4 | Kp 3 |
| Civil night, December 15 | 16.1 h | 16.6 h |
| Dark-season days | 295 | 279 |
| Nights with no civil darkness | 21 | 57 |
| Dark-month cloud, NASA POWER | 74% | 76% |
| Solar midnight, December 15 | 00:26 | 00:24 |
Turku 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. Seinäjoki sits at 60.5 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 3.
Civil night month by month
On December 15 Turku has 16.1 hours of civil night and Seinäjoki 16.6. Across the 15th of each month, Turku is darker in 6 months and Seinäjoki in 5. The widest gap comes in July, when Turku has 2.7 more hours.
| Month | Turku | Seinäjoki | Difference |
|---|---|---|---|
| January | 15.4 h | 15.9 h | -0.5 h |
| February | 13.2 h | 13.4 h | -0.2 h |
| March | 10.7 h | 10.6 h | +0.1 h |
| April | 7.6 h | 7.1 h | +0.5 h |
| May | 4.2 h | 2.8 h | +1.4 h |
| June | 0.0 h | 0.0 h | +0.0 h |
| July | 2.7 h | 0.0 h | +2.7 h |
| August | 6.4 h | 5.7 h | +0.7 h |
| September | 9.6 h | 9.4 h | +0.2 h |
| October | 12.3 h | 12.4 h | -0.1 h |
| November | 14.8 h | 15.1 h | -0.3 h |
| December | 16.1 h | 16.6 h | -0.5 h |
Season and midnight sun
Turku has no civil darkness from June 10 to June 30, 21 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 295 days. Seinäjoki has no civil darkness from May 23 to July 18, 57 nights in 2026, and its dark season, 4 or more evening hours of civil night, lasts 279 days.
Distance, cloud and time zones
The two towns are 262 km apart by great circle. In the dark months Turku averages 74% cloud and Seinäjoki 76%, from NASA POWER's 2001 to 2020 record. Turku's best month by civil night times clear sky is March. Seinäjoki's best month by civil night times clear sky is March. Time zones: Europe/Helsinki and Europe/Helsinki.
For tonight, open the live pages for Turku and Seinäjoki, which carry the live OVATION cell.
Questions
- Is Turku or Seinäjoki better for the northern lights?
- Seinäjoki sits closer to the oval, at 60.5 degrees geomagnetic against 58.4. 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, Turku or Seinäjoki?
- Seinäjoki, with 16.6 hours of civil night on December 15 against 16.1 in Turku.
- What Kp do Turku and Seinäjoki need?
- By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Turku needs about Kp 4 and Seinäjoki Kp 3 for the average oval edge to sit overhead.
- When is it too light for aurora in Turku and Seinäjoki?
- Turku: June 10 to June 30. Seinäjoki: May 23 to July 18.
- Which is clearer, Turku or Seinäjoki?
- Turku, with 74% mean cloud in the months with 4 hours or more of civil night against 76% in Seinäjoki (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.