Can you see the northern lights in Nuuk in September?

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

How dark is Nuuk in September?

Nuuk averages 9.2 hours of civil night a night in September 2027, from 7 h 31 min on the 1st to 10 h 51 min on the last night.

How cloudy is Nuuk in September?

NASA POWER's 2001 to 2020 climatology gives Nuuk's 1 degree cell 71% mean cloud in September, against 73% for the whole year. It is an all-hours average, not a forecast.

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

By darkness and moon alone, Sep 25, with 4 h of moon-free darkness inside 10 PM to 2 AM at Nuuk. Activity on that date will only be known hours ahead.

Is September or October better in Nuuk?

By civil night times the clear share, September scores 2.7 hours at Nuuk and October 3.6. October comes out ahead.

Nuuk · September 2027

Northern lights in Nuuk in September 2027

Answer

September gives Nuuk 9.2 hours of civil night on the 15th, the 7th darkest of its 12 months, under 71% mean cloud. 14% of September days since 1996 reached storm level, Kp 5.

9.2 h

civil night, average night

SunCalc for 64.18, -51.72; NASA POWER; GFZ Kp

September against the rest of the year

3.5

3.1

2.7

1.6

0.3

0.0

1.7

2.7

3.6

3.9

4.3

September cloud at Nuuk averages 71% in NASA POWER's 2001 to 2020 record, 2 points clearer than its yearly mean. July is Nuuk's clearest month at 67%. By civil night times clear sky, September scores 2.7 hours at Nuuk, 7th of 12. Reykjanesbær, 1,405 km away, averages 83%, cloudier by 12 points.

Civil night at Nuuk starts September at 7 h 31 min and reaches 10 h 51 min by September 30 as the nights lengthen by 3.3 hours. The 10 PM to 2 AM window is fully dark on 19 of 30 nights. True astronomical darkness, the sun 18 degrees down, lasts 4.6 hours on the 15th.

September night by night

Full moon comes first, on Sep 15, then the new moon on Sep 30, in America/Nuuk dates. Nuuk gets 142 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 25 (4 h), Sep 26 (4 h), Sep 27 (4 h).

1
3% lit
7.5 h
2
8% lit
7.7 h
3
15% lit
7.8 h
4
23% lit
7.9 h
5
33% lit
8.0 h
6
43% lit
8.1 h
7
53% lit
8.3 h
8
62% lit
8.4 h
9
71% lit
8.5 h
10
80% lit
5.9 h
11
87% lit
4.1 h
12
92% lit
2.5 h
13
97% lit
1.0 h
14
99% lit
0.0 h
15
100% lit
0.0 h
Full
16
99% lit
0.0 h
17
96% lit
0.0 h
18
91% lit
0.0 h
19
84% lit
0.0 h
20
75% lit
0.0 h
21
65% lit
0.0 h
22
54% lit
0.0 h
23
43% lit
0.1 h
24
32% lit
2.7 h
25
22% lit
4.9 h
26
13% lit
7.0 h
27
6% lit
9.0 h
28
2% lit
10.6 h
29
0% lit
10.8 h
30
1% lit
10.8 h
New

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

Quiet activity already puts the oval edge over Nuuk, so storm days matter more: 126 of the 900 September days from 1996 to 2025 (14%) reached Kp 5, one of the three most active months for that level. Nuuk sits at 72.5 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 0.

September across Greenland

Coming from August (5.3 hours at Nuuk), September adds darkness, and the nights keep growing into October (12.5 hours on the 15th). The September equinox falls on September 23, 04:56 Nuuk time, inside the weeks SWPC links with larger storms.

Darkness and moon, every night

Nuuk, 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	7 h 31 min	0 min	7 h 31 min	3 h 18 min	3%
Thu Sep 2	7 h 39 min	0 min	7 h 39 min	3 h 22 min	8%
Fri Sep 3	7 h 46 min	27 min	7 h 46 min	3 h 26 min	15%
Sat Sep 4	7 h 54 min	1 h 22 min	7 h 54 min	3 h 30 min	23%
Sun Sep 5	8 h 1 min	1 h 52 min	8 h 1 min	3 h 34 min	33%
Mon Sep 6	8 h 8 min	2 h 17 min	8 h 8 min	3 h 38 min	43%
Tue Sep 7	8 h 15 min	2 h 37 min	8 h 15 min	3 h 42 min	53%
Wed Sep 8	8 h 22 min	2 h 55 min	8 h 22 min	3 h 46 min	62%
Thu Sep 9	8 h 30 min	3 h 12 min	8 h 30 min	3 h 50 min	71%
Fri Sep 10	8 h 37 min	3 h 28 min	5 h 55 min	1 h 13 min	80%
Sat Sep 11	8 h 44 min	3 h 42 min	4 h 8 min	0 min	87%
Sun Sep 12	8 h 51 min	3 h 55 min	2 h 31 min	0 min	92%
Mon Sep 13	8 h 58 min	4 h 8 min	1 h	0 min	97%
Tue Sep 14	9 h 5 min	4 h 21 min	0 min	0 min	99%
Wed Sep 15	9 h 12 min	4 h 33 min	0 min	0 min	100%
Thu Sep 16	9 h 18 min	4 h 44 min	0 min	0 min	99%
Fri Sep 17	9 h 25 min	4 h 55 min	0 min	0 min	96%
Sat Sep 18	9 h 32 min	5 h 6 min	0 min	0 min	91%
Sun Sep 19	9 h 39 min	5 h 16 min	0 min	0 min	84%
Mon Sep 20	9 h 46 min	5 h 26 min	0 min	0 min	75%
Tue Sep 21	9 h 52 min	5 h 36 min	0 min	0 min	65%
Wed Sep 22	9 h 59 min	5 h 45 min	0 min	0 min	54%
Thu Sep 23	10 h 6 min	5 h 54 min	7 min	0 min	43%
Fri Sep 24	10 h 12 min	6 h 4 min	2 h 43 min	1 h 56 min	32%
Sat Sep 25	10 h 19 min	6 h 12 min	4 h 56 min	4 h	22%
Sun Sep 26	10 h 25 min	6 h 21 min	7 h 1 min	4 h	13%
Mon Sep 27	10 h 32 min	6 h 30 min	9 h	4 h	6%
Tue Sep 28	10 h 38 min	6 h 38 min	10 h 38 min	4 h	2%
Wed Sep 29	10 h 45 min	6 h 46 min	10 h 45 min	4 h	0%
Thu Sep 30	10 h 51 min	6 h 54 min	10 h 51 min	4 h	1%

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

Questions

Can you see the northern lights in Nuuk in September?: On dark, clear nights with enough activity. 30 of 30 nights at Nuuk have civil darkness, and 14% of past September days reached Kp 5.
How dark is Nuuk in September?: Nuuk averages 9.2 hours of civil night a night in September 2027, from 7 h 31 min on the 1st to 10 h 51 min on the last night.
How cloudy is Nuuk in September?: NASA POWER's 2001 to 2020 climatology gives Nuuk's 1 degree cell 71% mean cloud in September, against 73% for the whole year. It is an all-hours average, not a forecast.
What is the best night in September 2027 for aurora in Nuuk?: By darkness and moon alone, Sep 25, with 4 h of moon-free darkness inside 10 PM to 2 AM at Nuuk. Activity on that date will only be known hours ahead.
Is September or October better in Nuuk?: By civil night times the clear share, September scores 2.7 hours at Nuuk and October 3.6. 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.