Can you see the northern lights in Trångsund in April?

On dark, clear nights with enough activity. 30 of 30 nights at Trångsund have civil darkness, and 12% of past April days reached Kp 5.

How dark is Trångsund in April?

Trångsund averages 7.8 hours of civil night a night in April 2027, from 9 h 11 min on the 1st to 6 h 20 min on the last night.

How cloudy is Trångsund in April?

NASA POWER's 2001 to 2020 climatology gives Trångsund's 1 degree cell 69% mean cloud in April, against 75% for the whole year. It is an all-hours average, not a forecast.

What is the best night in April 2027 for aurora in Trångsund?

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

Is April or May better in Trångsund?

By civil night times the clear share, April scores 2.4 hours at Trångsund and May 1.8. April comes out ahead.

Trångsund · April 2027

Northern lights in Trångsund in April 2027

Answer

April gives Trångsund 7.8 hours of civil night on the 15th, the 8th darkest of its 12 months, under 69% mean cloud. 12% of April days since 1996 reached Kp 5, enough for the oval edge to reach Trångsund.

7.8 h

civil night, average night

SunCalc for 59.23, 18.13; NASA POWER; GFZ Kp

April against the rest of the year

1.7

1.8

2.4

1.8

0.8

1.3

2.1

2.7

2.3

1.9

April cloud at Trångsund averages 69% in NASA POWER's 2001 to 2020 record, 6 points clearer than its yearly mean. May is Trångsund's clearest month at 62%. By civil night times clear sky, April scores 2.4 hours at Trångsund, 2nd of 12. Stockholm, 11 km away, averages the same 69%.

Civil night at Trångsund starts April at 9 h 11 min and reaches 6 h 20 min by April 30, 2.9 hours shorter. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 3.0 hours on the 15th.

April night by night

April opens toward a new moon on Apr 7, with full moon on Apr 21, in Europe/Stockholm dates. Trångsund gets 128 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: Apr 1 (4 h), Apr 2 (4 h), Apr 3 (4 h).

1
24% lit
9.1 h
2
16% lit
9.1 h
3
10% lit
9.0 h
4
5% lit
8.9 h
5
1% lit
8.8 h
6
0% lit
8.7 h
7
1% lit
8.1 h
New
8
5% lit
6.4 h
9
10% lit
4.7 h
10
18% lit
3.0 h
11
28% lit
1.8 h
12
38% lit
1.1 h
13
50% lit
0.7 h
14
61% lit
0.5 h
15
72% lit
0.3 h
16
81% lit
0.2 h
17
89% lit
0.1 h
18
95% lit
0.0 h
19
99% lit
0.0 h
20
100% lit
0.0 h
21
99% lit
0.9 h
Full
22
96% lit
2.4 h
23
91% lit
3.8 h
24
84% lit
4.9 h
25
76% lit
5.5 h
26
68% lit
5.8 h
27
59% lit
6.0 h
28
49% lit
6.0 h
29
40% lit
6.0 h
30
31% lit
6.0 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 Aprils

Trångsund needs Kp 5 for the average oval edge to sit overhead. 106 of the 900 April days from 1996 to 2025 (12%) reached it in the GFZ Potsdam record, 4th of 12 months; storm days with Kp 5 or more made up 12%. Trångsund sits at 57.9 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.

April across Sweden

Trångsund ranks 6th in Sweden for civil night on April 15, behind Malmö at 8.3 hours. Coming from March (10.7 hours at Trångsund), April loses darkness, and May brings shorter nights (4.8 hours on the 15th).

Civil night on April 15 and April cloud, month-page towns in Sweden
Town	Civil night	Cloud
Malmö	8.3 h	59%
Helsingborg	8.3 h	66%
Gothenburg	8.1 h	65%
Jönköping	8.0 h	63%
Linköping	7.9 h	65%
Trångsund	7.8 h	69%
Stockholm	7.8 h	69%
Örebro	7.8 h	69%
Sollentuna	7.8 h	70%
Västerås	7.8 h	70%
Uppsala	7.7 h	70%
Hudiksvall	7.4 h	65%

Darkness and moon, every night

Trångsund, April 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
Thu Apr 1	9 h 11 min	5 h 23 min	9 h 7 min	4 h	24%
Fri Apr 2	9 h 5 min	5 h 15 min	9 h 5 min	4 h	16%
Sat Apr 3	8 h 59 min	5 h 6 min	8 h 59 min	4 h	10%
Sun Apr 4	8 h 54 min	4 h 58 min	8 h 54 min	4 h	5%
Mon Apr 5	8 h 48 min	4 h 49 min	8 h 48 min	4 h	1%
Tue Apr 6	8 h 42 min	4 h 40 min	8 h 42 min	4 h	0%
Wed Apr 7	8 h 37 min	4 h 30 min	8 h 4 min	4 h	1%
Thu Apr 8	8 h 31 min	4 h 20 min	6 h 23 min	3 h 19 min	5%
Fri Apr 9	8 h 25 min	4 h 10 min	4 h 39 min	1 h 38 min	10%
Sat Apr 10	8 h 19 min	4 h	3 h 2 min	4 min	18%
Sun Apr 11	8 h 13 min	3 h 49 min	1 h 49 min	0 min	28%
Mon Apr 12	8 h 8 min	3 h 38 min	1 h 5 min	0 min	38%
Tue Apr 13	8 h 2 min	3 h 26 min	42 min	0 min	50%
Wed Apr 14	7 h 56 min	3 h 13 min	28 min	0 min	61%
Thu Apr 15	7 h 50 min	3 h	19 min	0 min	72%
Fri Apr 16	7 h 44 min	2 h 46 min	12 min	0 min	81%
Sat Apr 17	7 h 38 min	2 h 30 min	6 min	0 min	89%
Sun Apr 18	7 h 32 min	2 h 13 min	0 min	0 min	95%
Mon Apr 19	7 h 26 min	1 h 54 min	0 min	0 min	99%
Tue Apr 20	7 h 20 min	1 h 31 min	0 min	0 min	100%
Wed Apr 21	7 h 14 min	59 min	53 min	2 min	99%
Thu Apr 22	7 h 8 min	0 min	2 h 25 min	1 h 37 min	96%
Fri Apr 23	7 h 2 min	0 min	3 h 50 min	3 h 4 min	91%
Sat Apr 24	6 h 56 min	0 min	4 h 55 min	4 h	84%
Sun Apr 25	6 h 50 min	0 min	5 h 33 min	4 h	76%
Mon Apr 26	6 h 44 min	0 min	5 h 51 min	4 h	68%
Tue Apr 27	6 h 38 min	0 min	5 h 59 min	4 h	59%
Wed Apr 28	6 h 32 min	0 min	6 h 2 min	4 h	49%
Thu Apr 29	6 h 26 min	0 min	6 h 3 min	4 h	40%
Fri Apr 30	6 h 20 min	0 min	6 h 2 min	4 h	31%

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

Questions

Can you see the northern lights in Trångsund in April?: On dark, clear nights with enough activity. 30 of 30 nights at Trångsund have civil darkness, and 12% of past April days reached Kp 5.
How dark is Trångsund in April?: Trångsund averages 7.8 hours of civil night a night in April 2027, from 9 h 11 min on the 1st to 6 h 20 min on the last night.
How cloudy is Trångsund in April?: NASA POWER's 2001 to 2020 climatology gives Trångsund's 1 degree cell 69% mean cloud in April, against 75% for the whole year. It is an all-hours average, not a forecast.
What is the best night in April 2027 for aurora in Trångsund?: By darkness and moon alone, Apr 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Trångsund. Activity on that date will only be known hours ahead.
Is April or May better in Trångsund?: By civil night times the clear share, April scores 2.4 hours at Trångsund and May 1.8. April 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.