Can you see the northern lights in Fort St. John in September?

On dark, clear nights with enough activity. 30 of 30 nights at Fort St. John have civil darkness, and 57% of past September days reached Kp 3.

How dark is Fort St. John in September?

Fort St. John averages 9.9 hours of civil night a night in September 2027, from 8 h 44 min on the 1st to 11 h 4 min on the last night.

How cloudy is Fort St. John in September?

NASA POWER's 2001 to 2020 climatology gives Fort St. John's 1 degree cell 65% mean cloud in September, against 67% for the whole year. It is an all-hours average, not a forecast.

What is the best night in September 2027 for aurora in Fort St. John?

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

Is September or October better in Fort St. John?

By civil night times the clear share, September scores 3.5 hours at Fort St. John and October 3.5. October comes out ahead.

Fort St. John · September 2027

Northern lights in Fort St. John in September 2027

Answer

September gives Fort St. John 9.9 hours of civil night on the 15th, the 7th darkest of its 12 months, under 65% mean cloud. 57% of September days since 1996 reached Kp 3, enough for the oval edge to reach Fort St. John.

9.9 h

civil night, average night

SunCalc for 56.25, -120.85; NASA POWER; GFZ Kp

September against the rest of the year

4.4

4.3

3.5

2.7

1.9

1.3

1.8

2.7

3.5

3.9

4.8

September cloud at Fort St. John averages 65% in NASA POWER's 2001 to 2020 record, 2 points clearer than its yearly mean. July is Fort St. John's clearest month at 63%. By civil night times clear sky, September scores 3.5 hours at Fort St. John, 6th of 12. Grande Prairie, 176 km away, averages 64%, clearer by 1 points.

Civil night at Fort St. John starts September at 8 h 44 min and reaches 11 h 4 min by September 30 as the nights lengthen by 2.3 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 6.7 hours on the 15th.

September night by night

Full moon comes first, on Sep 15, then the new moon on Sep 29, in America/Dawson_Creek dates. Fort St. John gets 152 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
4% lit
8.7 h
2
9% lit
8.8 h
3
17% lit
8.9 h
4
26% lit
9.0 h
5
35% lit
9.0 h
6
45% lit
8.6 h
7
55% lit
7.9 h
8
65% lit
7.0 h
9
74% lit
5.8 h
10
81% lit
4.5 h
11
88% lit
3.3 h
12
94% lit
2.0 h
13
97% lit
0.8 h
14
100% lit
0.0 h
15
100% lit
0.0 h
Full
16
98% lit
0.0 h
17
94% lit
0.0 h
18
89% lit
0.0 h
19
82% lit
0.0 h
20
73% lit
0.1 h
21
63% lit
0.8 h
22
52% lit
1.8 h
23
40% lit
3.1 h
24
29% lit
4.7 h
25
19% lit
6.3 h
26
11% lit
8.0 h
27
5% lit
9.7 h
28
1% lit
10.9 h
29
0% lit
11.0 h
New
30
2% lit
11.1 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

Fort St. John needs Kp 3 for the average oval edge to sit overhead. 514 of the 900 September days from 1996 to 2025 (57%) 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%. Fort St. John sits at 61.7 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.

September across Canada

Fort St. John ranks 20th in Canada for civil night on September 15, behind Québec at 10.4 hours. Coming from August (7.3 hours at Fort St. John), September adds darkness, and the nights keep growing into October (12.2 hours on the 15th). The September equinox falls on September 22, 22:56 Fort St. John 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%
Calgary	10.2 h	62%
Winnipeg	10.2 h	55%
Regina	10.2 h	55%
Kelowna	10.2 h	53%
Kamloops	10.2 h	58%
Fort St. John	9.9 h	65%

Darkness and moon, every night

Fort St. John, 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	8 h 44 min	5 h 6 min	8 h 44 min	4 h	4%
Thu Sep 2	8 h 49 min	5 h 14 min	8 h 49 min	4 h	9%
Fri Sep 3	8 h 54 min	5 h 21 min	8 h 54 min	4 h	17%
Sat Sep 4	8 h 59 min	5 h 28 min	8 h 59 min	4 h	26%
Sun Sep 5	9 h 4 min	5 h 35 min	8 h 58 min	4 h	35%
Mon Sep 6	9 h 9 min	5 h 42 min	8 h 33 min	4 h	45%
Tue Sep 7	9 h 14 min	5 h 49 min	7 h 53 min	4 h	55%
Wed Sep 8	9 h 19 min	5 h 56 min	6 h 57 min	3 h 16 min	65%
Thu Sep 9	9 h 24 min	6 h 3 min	5 h 48 min	2 h 5 min	74%
Fri Sep 10	9 h 29 min	6 h 9 min	4 h 33 min	48 min	81%
Sat Sep 11	9 h 33 min	6 h 16 min	3 h 16 min	0 min	88%
Sun Sep 12	9 h 38 min	6 h 22 min	2 h	0 min	94%
Mon Sep 13	9 h 43 min	6 h 28 min	45 min	0 min	97%
Tue Sep 14	9 h 48 min	6 h 35 min	0 min	0 min	100%
Wed Sep 15	9 h 53 min	6 h 41 min	0 min	0 min	100%
Thu Sep 16	9 h 58 min	6 h 47 min	0 min	0 min	98%
Fri Sep 17	10 h 2 min	6 h 53 min	0 min	0 min	94%
Sat Sep 18	10 h 7 min	6 h 59 min	0 min	0 min	89%
Sun Sep 19	10 h 12 min	7 h 5 min	0 min	0 min	82%
Mon Sep 20	10 h 17 min	7 h 11 min	9 min	0 min	73%
Tue Sep 21	10 h 22 min	7 h 16 min	48 min	0 min	63%
Wed Sep 22	10 h 26 min	7 h 22 min	1 h 47 min	0 min	52%
Thu Sep 23	10 h 31 min	7 h 28 min	3 h 7 min	47 min	40%
Fri Sep 24	10 h 36 min	7 h 33 min	4 h 41 min	2 h 19 min	29%
Sat Sep 25	10 h 41 min	7 h 39 min	6 h 21 min	3 h 56 min	19%
Sun Sep 26	10 h 45 min	7 h 44 min	8 h 1 min	4 h	11%
Mon Sep 27	10 h 50 min	7 h 50 min	9 h 39 min	4 h	5%
Tue Sep 28	10 h 55 min	7 h 55 min	10 h 55 min	4 h	1%
Wed Sep 29	10 h 59 min	8 h	10 h 59 min	4 h	0%
Thu Sep 30	11 h 4 min	8 h 6 min	11 h 4 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 Fort St. John in September?: On dark, clear nights with enough activity. 30 of 30 nights at Fort St. John have civil darkness, and 57% of past September days reached Kp 3.
How dark is Fort St. John in September?: Fort St. John averages 9.9 hours of civil night a night in September 2027, from 8 h 44 min on the 1st to 11 h 4 min on the last night.
How cloudy is Fort St. John in September?: NASA POWER's 2001 to 2020 climatology gives Fort St. John's 1 degree cell 65% mean cloud in September, against 67% for the whole year. It is an all-hours average, not a forecast.
What is the best night in September 2027 for aurora in Fort St. John?: By darkness and moon alone, Sep 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Fort St. John. Activity on that date will only be known hours ahead.
Is September or October better in Fort St. John?: By civil night times the clear share, September scores 3.5 hours at Fort St. John and October 3.5. October 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.