Can you see the northern lights in Anchorage in September?

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

How dark is Anchorage in September?

Anchorage averages 9.6 hours of civil night a night in September 2027, from 8 h 5 min on the 1st to 10 h 58 min on the last night.

How cloudy is Anchorage in September?

NASA POWER's 2001 to 2020 climatology gives Anchorage's 1 degree cell 78% mean cloud in September, against 74% for the whole year. It is an all-hours average, not a forecast.

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

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

Is September or October better in Anchorage?

By civil night times the clear share, September scores 2.1 hours at Anchorage and October 2.9. October comes out ahead.

Anchorage · September 2027

Northern lights in Anchorage in September 2027

Answer

September gives Anchorage 9.5 hours of civil night on the 15th, the 7th darkest of its 12 months, under 78% mean cloud. 57% of September days since 1996 reached Kp 3, enough for the oval edge to reach Anchorage.

9.6 h

civil night, average night

SunCalc for 61.22, -149.90; NASA POWER; GFZ Kp

September against the rest of the year

5.4

4.1

3.9

2.1

0.8

0.0

0.4

1.3

2.1

2.9

4.5

4.6

September cloud at Anchorage averages 78% in NASA POWER's 2001 to 2020 record, 4 points cloudier than its yearly mean. March is Anchorage's clearest month at 63%. By civil night times clear sky, September scores 2.1 hours at Anchorage, 7th of 12. Eagle River, 21 km away, averages the same 78%.

Civil night at Anchorage starts September at 8 h 5 min and reaches 10 h 58 min by September 30 as the nights lengthen by 2.9 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 5.6 hours on the 15th.

September night by night

Full moon comes first, on Sep 15, then the new moon on Sep 29, in America/Anchorage dates. Anchorage gets 147 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
8.1 h
2
9% lit
8.2 h
3
17% lit
8.3 h
4
26% lit
8.4 h
5
36% lit
8.5 h
6
46% lit
8.6 h
7
56% lit
8.7 h
8
65% lit
7.9 h
9
74% lit
6.5 h
10
82% lit
4.9 h
11
88% lit
3.5 h
12
94% lit
2.0 h
13
98% lit
0.6 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
81% lit
0.0 h
20
72% lit
0.0 h
21
62% lit
0.0 h
22
51% lit
0.6 h
23
40% lit
2.2 h
24
29% lit
4.0 h
25
19% lit
6.0 h
26
11% lit
7.8 h
27
4% lit
9.6 h
28
1% lit
10.8 h
29
0% lit
10.9 h
New
30
2% lit
11.0 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

Anchorage 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%. Anchorage sits at 61.9 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 United States

Anchorage ranks 8th in United States for civil night on September 15, behind Buffalo at 10.5 hours. Coming from August (6.3 hours at Anchorage), September adds darkness, and the nights keep growing into October (12.4 hours on the 15th). The September equinox falls on September 22, 21:56 Anchorage time, inside the weeks SWPC links with larger storms.

Civil night on September 15 and September cloud, month-page towns in United States
Town	Civil night	Cloud
Buffalo	10.5 h	57%
Portland, Maine	10.5 h	50%
Minneapolis	10.4 h	49%
Duluth	10.4 h	56%
Fargo	10.4 h	50%
Seattle	10.3 h	53%
Juneau	9.8 h	81%
Anchorage	9.5 h	78%
Eagle River	9.5 h	78%
Fairbanks	9.2 h	72%

Darkness and moon, every night

Anchorage, 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 5 min	3 h 7 min	8 h 5 min	4 h	4%
Thu Sep 2	8 h 11 min	3 h 21 min	8 h 11 min	4 h	9%
Fri Sep 3	8 h 18 min	3 h 34 min	8 h 18 min	4 h	17%
Sat Sep 4	8 h 24 min	3 h 46 min	8 h 24 min	4 h	26%
Sun Sep 5	8 h 30 min	3 h 58 min	8 h 30 min	4 h	36%
Mon Sep 6	8 h 36 min	4 h 9 min	8 h 36 min	4 h	46%
Tue Sep 7	8 h 43 min	4 h 20 min	8 h 43 min	4 h	56%
Wed Sep 8	8 h 49 min	4 h 30 min	7 h 54 min	3 h 32 min	65%
Thu Sep 9	8 h 55 min	4 h 41 min	6 h 27 min	2 h 2 min	74%
Fri Sep 10	9 h 1 min	4 h 50 min	4 h 56 min	28 min	82%
Sat Sep 11	9 h 7 min	5 h	3 h 27 min	0 min	88%
Sun Sep 12	9 h 13 min	5 h 9 min	2 h 1 min	0 min	94%
Mon Sep 13	9 h 19 min	5 h 18 min	38 min	0 min	98%
Tue Sep 14	9 h 25 min	5 h 27 min	0 min	0 min	100%
Wed Sep 15	9 h 31 min	5 h 36 min	0 min	0 min	100%
Thu Sep 16	9 h 37 min	5 h 44 min	0 min	0 min	98%
Fri Sep 17	9 h 43 min	5 h 52 min	0 min	0 min	94%
Sat Sep 18	9 h 49 min	6 h 1 min	0 min	0 min	89%
Sun Sep 19	9 h 55 min	6 h 9 min	0 min	0 min	81%
Mon Sep 20	10 h 1 min	6 h 16 min	0 min	0 min	72%
Tue Sep 21	10 h 6 min	6 h 24 min	0 min	0 min	62%
Wed Sep 22	10 h 12 min	6 h 32 min	35 min	0 min	51%
Thu Sep 23	10 h 18 min	6 h 39 min	2 h 10 min	53 min	40%
Fri Sep 24	10 h 24 min	6 h 46 min	4 h 2 min	2 h 42 min	29%
Sat Sep 25	10 h 30 min	6 h 54 min	5 h 57 min	4 h	19%
Sun Sep 26	10 h 35 min	7 h 1 min	7 h 50 min	4 h	11%
Mon Sep 27	10 h 41 min	7 h 8 min	9 h 38 min	4 h	4%
Tue Sep 28	10 h 47 min	7 h 15 min	10 h 47 min	4 h	1%
Wed Sep 29	10 h 53 min	7 h 22 min	10 h 53 min	4 h	0%
Thu Sep 30	10 h 58 min	7 h 28 min	10 h 58 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 Anchorage in September?: On dark, clear nights with enough activity. 30 of 30 nights at Anchorage have civil darkness, and 57% of past September days reached Kp 3.
How dark is Anchorage in September?: Anchorage averages 9.6 hours of civil night a night in September 2027, from 8 h 5 min on the 1st to 10 h 58 min on the last night.
How cloudy is Anchorage in September?: NASA POWER's 2001 to 2020 climatology gives Anchorage's 1 degree cell 78% mean cloud in September, against 74% for the whole year. It is an all-hours average, not a forecast.
What is the best night in September 2027 for aurora in Anchorage?: By darkness and moon alone, Sep 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Anchorage. Activity on that date will only be known hours ahead.
Is September or October better in Anchorage?: By civil night times the clear share, September scores 2.1 hours at Anchorage and October 2.9. 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.