Can you see the northern lights in Silkeborg in September?

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

How dark is Silkeborg in September?

Silkeborg averages 9.9 hours of civil night a night in September 2027, from 8 h 43 min on the 1st to 11 h 2 min on the last night.

How cloudy is Silkeborg in September?

NASA POWER's 2001 to 2020 climatology gives Silkeborg's 1 degree cell 64% mean cloud in September, against 69% for the whole year. It is an all-hours average, not a forecast.

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

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

Is September or October better in Silkeborg?

By civil night times the clear share, September scores 3.6 hours at Silkeborg and October 3.8. October comes out ahead.

Silkeborg · September 2027

Northern lights in Silkeborg in September 2027

Answer

September gives Silkeborg 9.9 hours of civil night on the 15th, the 7th darkest of its 12 months, under 64% mean cloud. 14% of September days since 1996 reached Kp 5, enough for the oval edge to reach Silkeborg.

9.9 h

civil night, average night

SunCalc for 56.17, 9.55; NASA POWER; GFZ Kp

September against the rest of the year

3.1

3.0

3.6

3.4

2.3

1.4

1.6

2.5

3.6

3.8

3.7

3.5

September cloud at Silkeborg averages 64% in NASA POWER's 2001 to 2020 record, 5 points clearer than its yearly mean. April is Silkeborg's clearest month at 59%. By civil night times clear sky, September scores 3.6 hours at Silkeborg, 3rd of 12. Århus, 41 km away, averages 66%, cloudier by 2 points.

Civil night at Silkeborg starts September at 8 h 43 min and reaches 11 h 2 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 16, then the new moon on Sep 30, in Europe/Copenhagen dates. Silkeborg gets 151 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
2% lit
8.7 h
2
7% lit
8.8 h
3
14% lit
8.9 h
4
22% lit
9.0 h
5
32% lit
9.1 h
6
42% lit
8.7 h
7
52% lit
8.2 h
8
61% lit
7.3 h
9
70% lit
6.2 h
10
79% lit
5.0 h
11
86% lit
3.7 h
12
92% lit
2.5 h
13
96% lit
1.2 h
14
99% lit
0.0 h
15
100% lit
0.0 h
16
99% lit
0.0 h
Full
17
96% lit
0.0 h
18
91% lit
0.0 h
19
85% lit
0.0 h
20
76% lit
0.0 h
21
67% lit
0.6 h
22
56% lit
1.4 h
23
45% lit
2.6 h
24
33% lit
4.1 h
25
23% lit
5.8 h
26
14% lit
7.4 h
27
7% lit
9.1 h
28
2% lit
10.7 h
29
0% lit
11.0 h
30
1% lit
11.0 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

Silkeborg 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%. Silkeborg 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 Denmark

No month-page town in Denmark has more civil night on September 15 than Silkeborg; the national median is 9.9 hours. Coming from August (7.3 hours at Silkeborg), September adds darkness, and the nights keep growing into October (12.2 hours on the 15th). The September equinox falls on September 23, 07:56 Silkeborg time, inside the weeks SWPC links with larger storms.

Civil night on September 15 and September cloud, month-page towns in Denmark
Town	Civil night	Cloud
Silkeborg	9.9 h	64%
Copenhagen	9.9 h	65%
Århus	9.9 h	66%
Odense	9.9 h	62%
Aalborg	9.8 h	71%

Darkness and moon, every night

Silkeborg, 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 43 min	5 h 5 min	8 h 43 min	4 h	2%
Thu Sep 2	8 h 48 min	5 h 12 min	8 h 48 min	4 h	7%
Fri Sep 3	8 h 53 min	5 h 19 min	8 h 53 min	4 h	14%
Sat Sep 4	8 h 58 min	5 h 27 min	8 h 58 min	4 h	22%
Sun Sep 5	9 h 3 min	5 h 34 min	9 h 3 min	4 h	32%
Mon Sep 6	9 h 8 min	5 h 41 min	8 h 43 min	4 h	42%
Tue Sep 7	9 h 12 min	5 h 48 min	8 h 9 min	4 h	52%
Wed Sep 8	9 h 17 min	5 h 54 min	7 h 18 min	3 h 20 min	61%
Thu Sep 9	9 h 22 min	6 h 1 min	6 h 14 min	2 h 13 min	70%
Fri Sep 10	9 h 27 min	6 h 8 min	5 h	57 min	79%
Sat Sep 11	9 h 32 min	6 h 14 min	3 h 44 min	0 min	86%
Sun Sep 12	9 h 37 min	6 h 21 min	2 h 27 min	0 min	92%
Mon Sep 13	9 h 42 min	6 h 27 min	1 h 12 min	0 min	96%
Tue Sep 14	9 h 47 min	6 h 33 min	0 min	0 min	99%
Wed Sep 15	9 h 51 min	6 h 39 min	0 min	0 min	100%
Thu Sep 16	9 h 56 min	6 h 45 min	0 min	0 min	99%
Fri Sep 17	10 h 1 min	6 h 51 min	0 min	0 min	96%
Sat Sep 18	10 h 6 min	6 h 57 min	0 min	0 min	91%
Sun Sep 19	10 h 11 min	7 h 3 min	0 min	0 min	85%
Mon Sep 20	10 h 15 min	7 h 9 min	0 min	0 min	76%
Tue Sep 21	10 h 20 min	7 h 15 min	33 min	0 min	67%
Wed Sep 22	10 h 25 min	7 h 21 min	1 h 24 min	0 min	56%
Thu Sep 23	10 h 30 min	7 h 26 min	2 h 37 min	36 min	45%
Fri Sep 24	10 h 34 min	7 h 32 min	4 h 7 min	2 h 4 min	33%
Sat Sep 25	10 h 39 min	7 h 37 min	5 h 46 min	3 h 40 min	23%
Sun Sep 26	10 h 44 min	7 h 43 min	7 h 26 min	4 h	14%
Mon Sep 27	10 h 48 min	7 h 48 min	9 h 4 min	4 h	7%
Tue Sep 28	10 h 53 min	7 h 54 min	10 h 41 min	4 h	2%
Wed Sep 29	10 h 58 min	7 h 59 min	10 h 58 min	4 h	0%
Thu Sep 30	11 h 2 min	8 h 4 min	11 h 2 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 Silkeborg in September?: On dark, clear nights with enough activity. 30 of 30 nights at Silkeborg have civil darkness, and 14% of past September days reached Kp 5.
How dark is Silkeborg in September?: Silkeborg averages 9.9 hours of civil night a night in September 2027, from 8 h 43 min on the 1st to 11 h 2 min on the last night.
How cloudy is Silkeborg in September?: NASA POWER's 2001 to 2020 climatology gives Silkeborg's 1 degree cell 64% mean cloud in September, against 69% for the whole year. It is an all-hours average, not a forecast.
What is the best night in September 2027 for aurora in Silkeborg?: By darkness and moon alone, Sep 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Silkeborg. Activity on that date will only be known hours ahead.
Is September or October better in Silkeborg?: By civil night times the clear share, September scores 3.6 hours at Silkeborg and October 3.8. 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.