Can you see the northern lights in Lethbridge in September?

On dark, clear nights with enough activity. 30 of 30 nights at Lethbridge have civil darkness, and 14% of past September days reached Kp 5.

How dark is Lethbridge in September?

Lethbridge averages 10.3 hours of civil night a night in September 2027, from 9 h 20 min on the 1st to 11 h 9 min on the last night.

How cloudy is Lethbridge in September?

NASA POWER's 2001 to 2020 climatology gives Lethbridge's 1 degree cell 56% mean cloud in September, against 63% for the whole year. It is an all-hours average, not a forecast.

What is the best night in September 2027 for aurora in Lethbridge?

By darkness and moon alone, Sep 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Lethbridge. Activity on that date will only be known hours ahead.

Is September or October better in Lethbridge?

By civil night times the clear share, September scores 4.5 hours at Lethbridge and October 4.2. September comes out ahead.

Lethbridge · September 2027

Northern lights in Lethbridge in September 2027

Answer

September gives Lethbridge 10.2 hours of civil night on the 15th, the 7th darkest of its 12 months, under 56% mean cloud. 14% of September days since 1996 reached Kp 5, enough for the oval edge to reach Lethbridge.

10.3 h

civil night, average night

SunCalc for 49.70, -112.82; NASA POWER; GFZ Kp

September against the rest of the year

4.1

3.9

3.4

2.9

2.5

2.4

3.8

4.1

4.5

4.2

4.5

September cloud at Lethbridge averages 56% in NASA POWER's 2001 to 2020 record, 7 points clearer than its yearly mean. July is Lethbridge's clearest month at 42%. By civil night times clear sky, September scores 4.5 hours at Lethbridge, 2nd of 12. Calgary, 175 km away, averages 62%, cloudier by 6 points.

Civil night at Lethbridge starts September at 9 h 20 min and reaches 11 h 9 min by September 30 as the nights lengthen by 1.8 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 7.6 hours on the 15th.

September night by night

Full moon comes first, on Sep 15, then the new moon on Sep 29, in America/Edmonton dates. Lethbridge gets 156 hours of civil night with the moon below the horizon across the month. The best of them for moon-free darkness inside 10 PM to 2 AM: Sep 1 (4 h), Sep 2 (4 h), Sep 3 (4 h).

1
3% lit
9.3 h
2
9% lit
9.4 h
3
16% lit
9.3 h
4
25% lit
9.0 h
5
35% lit
8.6 h
6
45% lit
8.0 h
7
55% lit
7.2 h
8
64% lit
6.3 h
9
73% lit
5.3 h
10
81% lit
4.2 h
11
88% lit
3.0 h
12
93% lit
1.9 h
13
97% lit
0.8 h
14
99% lit
0.0 h
15
100% lit
0.0 h
Full
16
98% lit
0.0 h
17
95% lit
0.0 h
18
89% lit
0.0 h
19
82% lit
0.4 h
20
73% lit
1.0 h
21
63% lit
1.7 h
22
52% lit
2.7 h
23
41% lit
4.0 h
24
30% lit
5.3 h
25
20% lit
6.8 h
26
11% lit
8.3 h
27
5% lit
9.8 h
28
1% lit
11.0 h
29
0% lit
11.1 h
New
30
2% lit
11.2 h

Each cell is the night that starts on that date. Hours are civil-dark time with the moon below the horizon; the green rule scales with them. Green outline: new moon. Bone outline: full moon.

Activity in past Septembers

Lethbridge needs Kp 5 for the average oval edge to sit overhead. 126 of the 900 September days from 1996 to 2025 (14%) reached it in the GFZ Potsdam record, one of the three most active months for that level; storm days with Kp 5 or more made up 14%. 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.

September across Canada

Lethbridge ranks 8th in Canada for civil night on September 15, behind Québec at 10.4 hours. Coming from August (8.3 hours at Lethbridge), September adds darkness, and the nights keep growing into October (12.1 hours on the 15th). The September equinox falls on September 22, 23:56 Lethbridge time, inside the weeks SWPC links with larger storms.

Civil night on September 15 and September cloud, month-page towns in Canada
Town	Civil night	Cloud
Québec	10.4 h	57%
Greater Sudbury	10.4 h	58%
Trois-Rivières	10.4 h	56%
Sydney	10.4 h	64%
Saguenay	10.3 h	65%
St. John's	10.3 h	69%
Thunder Bay	10.3 h	65%
Lethbridge	10.2 h	56%
Calgary	10.2 h	62%
Winnipeg	10.2 h	55%
Regina	10.2 h	55%
Kelowna	10.2 h	53%

Darkness and moon, every night

Lethbridge, September 2027: each night from local noon to the next noon
Night	Civil	Astronomical	Moon-free dark	Moon-free, 10 PM to 2 AM	Moon lit
Wed Sep 1	9 h 20 min	6 h 30 min	9 h 20 min	4 h	3%
Thu Sep 2	9 h 24 min	6 h 35 min	9 h 24 min	4 h	9%
Fri Sep 3	9 h 28 min	6 h 39 min	9 h 20 min	4 h	16%
Sat Sep 4	9 h 32 min	6 h 44 min	8 h 59 min	4 h	25%
Sun Sep 5	9 h 36 min	6 h 49 min	8 h 33 min	4 h	35%
Mon Sep 6	9 h 39 min	6 h 54 min	7 h 58 min	3 h 39 min	45%
Tue Sep 7	9 h 43 min	6 h 59 min	7 h 14 min	2 h 53 min	55%
Wed Sep 8	9 h 47 min	7 h 3 min	6 h 19 min	1 h 57 min	64%
Thu Sep 9	9 h 51 min	7 h 8 min	5 h 17 min	53 min	73%
Fri Sep 10	9 h 54 min	7 h 13 min	4 h 10 min	0 min	81%
Sat Sep 11	9 h 58 min	7 h 17 min	3 h 2 min	0 min	88%
Sun Sep 12	10 h 2 min	7 h 22 min	1 h 54 min	0 min	93%
Mon Sep 13	10 h 6 min	7 h 26 min	47 min	0 min	97%
Tue Sep 14	10 h 10 min	7 h 31 min	0 min	0 min	99%
Wed Sep 15	10 h 13 min	7 h 35 min	0 min	0 min	100%
Thu Sep 16	10 h 17 min	7 h 39 min	0 min	0 min	98%
Fri Sep 17	10 h 21 min	7 h 44 min	0 min	0 min	95%
Sat Sep 18	10 h 25 min	7 h 48 min	0 min	0 min	89%
Sun Sep 19	10 h 28 min	7 h 53 min	24 min	0 min	82%
Mon Sep 20	10 h 32 min	7 h 57 min	58 min	0 min	73%
Tue Sep 21	10 h 36 min	8 h 1 min	1 h 43 min	0 min	63%
Wed Sep 22	10 h 40 min	8 h 5 min	2 h 43 min	48 min	52%
Thu Sep 23	10 h 43 min	8 h 10 min	3 h 57 min	1 h 59 min	41%
Fri Sep 24	10 h 47 min	8 h 14 min	5 h 21 min	3 h 21 min	30%
Sat Sep 25	10 h 51 min	8 h 18 min	6 h 50 min	4 h	20%
Sun Sep 26	10 h 54 min	8 h 22 min	8 h 19 min	4 h	11%
Mon Sep 27	10 h 58 min	8 h 26 min	9 h 47 min	4 h	5%
Tue Sep 28	11 h 2 min	8 h 30 min	11 h 2 min	4 h	1%
Wed Sep 29	11 h 6 min	8 h 34 min	11 h 6 min	4 h	0%
Thu Sep 30	11 h 9 min	8 h 38 min	11 h 9 min	4 h	2%

Moon lit: SunCalc illuminated fraction at the middle of the 10 PM to 2 AM window.

Questions

Can you see the northern lights in Lethbridge in September?: On dark, clear nights with enough activity. 30 of 30 nights at Lethbridge have civil darkness, and 14% of past September days reached Kp 5.
How dark is Lethbridge in September?: Lethbridge averages 10.3 hours of civil night a night in September 2027, from 9 h 20 min on the 1st to 11 h 9 min on the last night.
How cloudy is Lethbridge in September?: NASA POWER's 2001 to 2020 climatology gives Lethbridge's 1 degree cell 56% mean cloud in September, against 63% for the whole year. It is an all-hours average, not a forecast.
What is the best night in September 2027 for aurora in Lethbridge?: By darkness and moon alone, Sep 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Lethbridge. Activity on that date will only be known hours ahead.
Is September or October better in Lethbridge?: By civil night times the clear share, September scores 4.5 hours at Lethbridge and October 4.2. September comes out ahead.

Sources and verification

SunCalchttps://github.com/mourner/suncalc
NASA POWER climatologyhttps://power.larc.nasa.gov/docs/services/api/temporal/climatology/
GFZ Potsdam Kp indexhttps://kp.gfz.de/en/data
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.