Is Calgary or Lethbridge better for the northern lights?

Calgary sits closer to the oval, at 57.5 degrees geomagnetic against 56.3. 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, Calgary or Lethbridge?

Calgary, with 14.6 hours of civil night on December 15 against 14.5 in Lethbridge.

What Kp do Calgary and Lethbridge need?

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

When is it too light for aurora in Calgary and Lethbridge?

Calgary: never, every night has civil darkness. Lethbridge: never, every night has civil darkness.

Which is clearer, Calgary or Lethbridge?

Lethbridge, with 63% mean cloud in the months with 4 hours or more of civil night against 67% in Calgary (NASA POWER, 2001 to 2020).

Comparison

Calgary vs Lethbridge for the northern lights

Answer

Calgary sits 1.2 degrees higher on the IGRF-14 dipole, 57.5 against 56.3. By SWPC's oval-edge rule Calgary needs about Kp 5 for the average edge to sit overhead and Lethbridge Kp 5. On the map Calgary is also closer to the pole, by 1.4 degrees.

57.5° / 56.3°

dipole latitude

Side by side

Computed figures for both towns
Figure	Calgary	Lethbridge
Dipole latitude	57.5°	56.3°
Kp for the oval edge overhead	Kp 5	Kp 5
Civil night, December 15	14.6 h	14.5 h
Dark-season days	365	365
Nights with no civil darkness	0	0
Dark-month cloud, NASA POWER	67%	63%
Solar midnight, December 15	01:32	01:27

Calgary sits at 57.5 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. Lethbridge sits at 56.3 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.

Civil night month by month

On December 15 Calgary has 14.6 hours of civil night and Lethbridge 14.5. Across the 15th of each month, Calgary is darker in 4 months and Lethbridge in 5. The widest gap comes in May, when Lethbridge has 0.3 more hours.

Hours of civil night on the 15th of each month, 2026
Month	Calgary	Lethbridge	Difference
January	14.2 h	14.1 h	+0.1 h
February	12.7 h	12.6 h	+0.1 h
March	10.9 h	10.9 h	+0.0 h
April	8.8 h	9.0 h	-0.2 h
May	6.9 h	7.2 h	-0.3 h
June	5.8 h	6.1 h	-0.3 h
July	6.3 h	6.6 h	-0.3 h
August	8.1 h	8.3 h	-0.2 h
September	10.2 h	10.2 h	+0.0 h
October	12.1 h	12.1 h	+0.0 h
November	13.8 h	13.7 h	+0.1 h
December	14.6 h	14.5 h	+0.1 h

Difference: Calgary minus Lethbridge. Each figure links to that town's month page.

Season and midnight sun

Calgary has some civil darkness every night of 2026, and clears Glow's 4-hour dark-season bar every evening. Lethbridge 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 175 km apart by great circle. In the dark months Lethbridge averages 63% cloud and Calgary 67%, from NASA POWER's 2001 to 2020 record. Calgary's best month by civil night times clear sky is December. Lethbridge's best month by civil night times clear sky is December. Time zones: America/Edmonton and America/Edmonton.

For tonight, open the live pages for Calgary and Lethbridge, which carry the live OVATION cell.

Questions

Is Calgary or Lethbridge better for the northern lights?: Calgary sits closer to the oval, at 57.5 degrees geomagnetic against 56.3. 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, Calgary or Lethbridge?: Calgary, with 14.6 hours of civil night on December 15 against 14.5 in Lethbridge.
What Kp do Calgary and Lethbridge need?: By SWPC's rule of 66 degrees at Kp 0 and 2 degrees per step, Calgary needs about Kp 5 and Lethbridge Kp 5 for the average oval edge to sit overhead.
When is it too light for aurora in Calgary and Lethbridge?: Calgary: never, every night has civil darkness. Lethbridge: never, every night has civil darkness.
Which is clearer, Calgary or Lethbridge?: Lethbridge, with 63% mean cloud in the months with 4 hours or more of civil night against 67% in Calgary (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.