Can you see the northern lights in Siilinjärvi in August?

On dark, clear nights with enough activity. 31 of 31 nights at Siilinjärvi have civil darkness, and 48% of past August days reached Kp 3.

How dark is Siilinjärvi in August?

Siilinjärvi averages 5.7 hours of civil night a night in August 2027, from 3 h 29 min on the 1st to 7 h 36 min on the last night.

How cloudy is Siilinjärvi in August?

NASA POWER's 2001 to 2020 climatology gives Siilinjärvi's 1 degree cell 68% mean cloud in August, against 75% for the whole year. It is an all-hours average, not a forecast.

What is the best night in August 2027 for aurora in Siilinjärvi?

By darkness and moon alone, Aug 29, with 4 h of moon-free darkness inside 10 PM to 2 AM at Siilinjärvi. Activity on that date will only be known hours ahead.

Is August or September better in Siilinjärvi?

By civil night times the clear share, August scores 1.8 hours at Siilinjärvi and September 2.6. September comes out ahead.

Siilinjärvi · August 2027

Northern lights in Siilinjärvi in August 2027

Answer

August gives Siilinjärvi 5.6 hours of civil night on the 15th, the 9th darkest of its 12 months, under 68% mean cloud. 48% of August days since 1996 reached Kp 3, enough for the oval edge to reach Siilinjärvi.

5.7 h

civil night, average night

SunCalc for 63.08, 27.67; NASA POWER; GFZ Kp

August against the rest of the year

3.3

3.1

3.2

2.1

0.8

0.0

1.8

2.6

2.1

1.8

2.8

August cloud at Siilinjärvi averages 68% in NASA POWER's 2001 to 2020 record, 7 points clearer than its yearly mean. June is Siilinjärvi's clearest month at 68%. By civil night times clear sky, August scores 1.8 hours at Siilinjärvi, 9th of 12. Kuopio, 21 km away, averages 69%, cloudier by 1 points.

Civil night at Siilinjärvi starts August at 3 h 29 min and reaches 7 h 36 min by August 31 as the nights lengthen by 4.1 hours. The 10 PM to 2 AM window is fully dark on 10 of 31 nights. The sun never reaches 18 degrees down, so Siilinjärvi gets no astronomical night in August.

August night by night

August opens toward a new moon on Aug 2 and Aug 31, with full moon on Aug 17, in Europe/Helsinki dates. Siilinjärvi gets 85 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: Aug 29 (4 h), Aug 30 (4 h), Aug 31 (4 h).

1
0% lit
3.5 h
2
0% lit
3.6 h
New
3
3% lit
3.8 h
4
9% lit
4.0 h
5
17% lit
4.2 h
6
26% lit
4.3 h
7
36% lit
4.5 h
8
47% lit
4.6 h
9
57% lit
4.8 h
10
67% lit
4.9 h
11
76% lit
5.0 h
12
83% lit
5.2 h
13
90% lit
4.0 h
14
95% lit
2.1 h
15
98% lit
0.5 h
16
100% lit
0.0 h
17
100% lit
0.0 h
Full
18
98% lit
0.0 h
19
94% lit
0.0 h
20
88% lit
0.0 h
21
81% lit
0.0 h
22
73% lit
0.0 h
23
63% lit
0.0 h
24
53% lit
0.0 h
25
42% lit
0.0 h
26
31% lit
0.0 h
27
21% lit
1.3 h
28
12% lit
3.5 h
29
5% lit
5.7 h
30
1% lit
7.5 h
31
0% lit
7.6 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 Augusts

Siilinjärvi needs Kp 3 for the average oval edge to sit overhead. 444 of the 930 August days from 1996 to 2025 (48%) reached it in the GFZ Potsdam record, 7th of 12 months; storm days with Kp 5 or more made up 11%. Siilinjärvi sits at 60.1 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.

August across Finland

Siilinjärvi ranks 11th in Finland for civil night on August 15, behind Helsinki at 6.5 hours. Coming from July (0.0 hours at Siilinjärvi), August adds darkness, and the nights keep growing into September (9.3 hours on the 15th).

Civil night on August 15 and August cloud, month-page towns in Finland
Town	Civil night	Cloud
Helsinki	6.5 h	63%
Espoo	6.5 h	63%
Vantaa	6.4 h	63%
Turku	6.4 h	63%
Lahti	6.3 h	63%
Tampere	6.1 h	65%
Jyväskylä	5.9 h	67%
Kurikka	5.8 h	64%
Kuopio	5.7 h	69%
Seinäjoki	5.7 h	64%
Siilinjärvi	5.6 h	68%
Vaasa	5.6 h	66%

Darkness and moon, every night

Siilinjärvi, August 2027: each night from local noon to the next noon
Night	Civil	Moon-free dark	Moon-free, 10 PM to 2 AM	Moon lit
Sun Aug 1	3 h 29 min	3 h 29 min	2 h 28 min	0%
Mon Aug 2	3 h 39 min	3 h 39 min	2 h 34 min	0%
Tue Aug 3	3 h 49 min	3 h 49 min	2 h 39 min	3%
Wed Aug 4	3 h 59 min	3 h 59 min	2 h 44 min	9%
Thu Aug 5	4 h 9 min	4 h 9 min	2 h 48 min	17%
Fri Aug 6	4 h 18 min	4 h 18 min	2 h 53 min	26%
Sat Aug 7	4 h 27 min	4 h 27 min	2 h 58 min	36%
Sun Aug 8	4 h 36 min	4 h 36 min	3 h 3 min	47%
Mon Aug 9	4 h 45 min	4 h 45 min	3 h 7 min	57%
Tue Aug 10	4 h 54 min	4 h 54 min	3 h 12 min	67%
Wed Aug 11	5 h 2 min	5 h 2 min	3 h 16 min	76%
Thu Aug 12	5 h 11 min	5 h 11 min	3 h 20 min	83%
Fri Aug 13	5 h 19 min	3 h 57 min	2 h 3 min	90%
Sat Aug 14	5 h 27 min	2 h 8 min	10 min	95%
Sun Aug 15	5 h 35 min	31 min	0 min	98%
Mon Aug 16	5 h 43 min	0 min	0 min	100%
Tue Aug 17	5 h 51 min	0 min	0 min	100%
Wed Aug 18	5 h 59 min	0 min	0 min	98%
Thu Aug 19	6 h 7 min	0 min	0 min	94%
Fri Aug 20	6 h 15 min	0 min	0 min	88%
Sat Aug 21	6 h 22 min	0 min	0 min	81%
Sun Aug 22	6 h 30 min	0 min	0 min	73%
Mon Aug 23	6 h 37 min	0 min	0 min	63%
Tue Aug 24	6 h 45 min	0 min	0 min	53%
Wed Aug 25	6 h 52 min	0 min	0 min	42%
Thu Aug 26	7 h	0 min	0 min	31%
Fri Aug 27	7 h 7 min	1 h 18 min	56 min	21%
Sat Aug 28	7 h 14 min	3 h 33 min	3 h 7 min	12%
Sun Aug 29	7 h 21 min	5 h 43 min	4 h	5%
Mon Aug 30	7 h 28 min	7 h 28 min	4 h	1%
Tue Aug 31	7 h 36 min	7 h 36 min	4 h	0%

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

Questions

Can you see the northern lights in Siilinjärvi in August?: On dark, clear nights with enough activity. 31 of 31 nights at Siilinjärvi have civil darkness, and 48% of past August days reached Kp 3.
How dark is Siilinjärvi in August?: Siilinjärvi averages 5.7 hours of civil night a night in August 2027, from 3 h 29 min on the 1st to 7 h 36 min on the last night.
How cloudy is Siilinjärvi in August?: NASA POWER's 2001 to 2020 climatology gives Siilinjärvi's 1 degree cell 68% mean cloud in August, against 75% for the whole year. It is an all-hours average, not a forecast.
What is the best night in August 2027 for aurora in Siilinjärvi?: By darkness and moon alone, Aug 29, with 4 h of moon-free darkness inside 10 PM to 2 AM at Siilinjärvi. Activity on that date will only be known hours ahead.
Is August or September better in Siilinjärvi?: By civil night times the clear share, August scores 1.8 hours at Siilinjärvi and September 2.6. September 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.