Is Preston or Bolton better for the northern lights?

Preston sits closer to the oval, at 55.9 degrees geomagnetic against 55.7. 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, Preston or Bolton?

Preston, with 15.0 hours of civil night on December 15 against 15.0 in Bolton.

What Kp do Preston and Bolton need?

By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Preston needs about Kp 6 and Bolton Kp 6 for the average oval edge to sit overhead.

When is it too light for aurora in Preston and Bolton?

Preston: never, every night has civil darkness. Bolton: never, every night has civil darkness.

Which is clearer, Preston or Bolton?

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

Comparison

Preston vs Bolton for the northern lights

Answer

Preston sits 0.2 degrees higher on the IGRF-14 dipole, 55.9 against 55.7. By SWPC's oval-edge rule Preston needs about Kp 6 for the average edge to sit overhead and Bolton Kp 6. On the map Preston is also closer to the pole, by 0.2 degrees.

55.9° / 55.7°

dipole latitude

Side by side

Computed figures for both towns
Figure	Preston	Bolton
Dipole latitude	55.9°	55.7°
Kp for the oval edge overhead	Kp 6	Kp 6
Civil night, December 15	15.0 h	15.0 h
Dark-season days	365	365
Nights with no civil darkness	0	0
Dark-month cloud, NASA POWER	77%	77%
Solar midnight, December 15	00:06	00:05

Preston sits at 55.9 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 6, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less. Bolton sits at 55.7 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 6, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less.

Civil night month by month

On December 15 Preston has 15.0 hours of civil night and Bolton 15.0. Across the 15th of each month, Preston is darker in 0 months and Bolton in 2. The widest gap comes in July, when Bolton has 0.1 more hours.

Hours of civil night on the 15th of each month, 2026
Month	Preston	Bolton	Difference
January	14.5 h	14.5 h	+0.0 h
February	12.8 h	12.8 h	+0.0 h
March	10.9 h	10.9 h	+0.0 h
April	8.6 h	8.6 h	+0.0 h
May	6.4 h	6.4 h	+0.0 h
June	5.0 h	5.0 h	+0.0 h
July	5.6 h	5.7 h	-0.1 h
August	7.7 h	7.8 h	-0.1 h
September	10.0 h	10.0 h	+0.0 h
October	12.1 h	12.1 h	+0.0 h
November	14.0 h	14.0 h	+0.0 h
December	15.0 h	15.0 h	+0.0 h

Difference: Preston minus Bolton. Each figure links to that town's month page.

Season and midnight sun

Preston has some civil darkness every night of 2026, and clears Glow's 4-hour dark-season bar every evening. Bolton has some civil darkness every night of 2026, and clears Glow's 4-hour dark-season bar every evening.

Distance, cloud and time zones

The two towns are 27 km apart by great circle. In the dark months both average about 77% cloud in NASA POWER's 2001 to 2020 record. Preston's best month by civil night times clear sky is December. Bolton's best month by civil night times clear sky is December. Time zones: Europe/London and Europe/London.

For tonight, open the live pages for Preston and Bolton, which carry the live OVATION cell.

Questions

Is Preston or Bolton better for the northern lights?: Preston sits closer to the oval, at 55.9 degrees geomagnetic against 55.7. 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, Preston or Bolton?: Preston, with 15.0 hours of civil night on December 15 against 15.0 in Bolton.
What Kp do Preston and Bolton need?: By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Preston needs about Kp 6 and Bolton Kp 6 for the average oval edge to sit overhead.
When is it too light for aurora in Preston and Bolton?: Preston: never, every night has civil darkness. Bolton: never, every night has civil darkness.
Which is clearer, Preston or Bolton?: Preston, with 77% mean cloud in the months with 4 hours or more of civil night against 77% in Bolton (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.