Can you see the northern lights in Mäntsälä in January?

On dark, clear nights with enough activity. 31 of 31 nights at Mäntsälä have civil darkness, and 21% of past January days reached Kp 4.

How dark is Mäntsälä in January?

Mäntsälä averages 15.3 hours of civil night a night in January 2027, from 16 h 2 min on the 1st to 14 h 25 min on the last night.

How cloudy is Mäntsälä in January?

NASA POWER's 2001 to 2020 climatology gives Mäntsälä's 1 degree cell 82% mean cloud in January, against 72% for the whole year. It is an all-hours average, not a forecast.

What is the best night in January 2027 for aurora in Mäntsälä?

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

Is January or February better in Mäntsälä?

By civil night times the clear share, January scores 2.8 hours at Mäntsälä and February 2.8. January comes out ahead.

Mäntsälä · January 2027

Northern lights in Mäntsälä in January 2027

Answer

January gives Mäntsälä 15.5 hours of civil night on the 15th, the 2nd darkest of its 12 months, under 82% mean cloud. 21% of January days since 1996 reached Kp 4, enough for the oval edge to reach Mäntsälä.

15.3 h

civil night, average night

SunCalc for 60.63, 25.32; NASA POWER; GFZ Kp

January against the rest of the year

2.8

3.3

2.5

1.6

0.0

0.9

2.4

3.2

2.7

2.2

2.4

January cloud at Mäntsälä averages 82% in NASA POWER's 2001 to 2020 record, 10 points cloudier than its yearly mean. May is Mäntsälä's clearest month at 62%. By civil night times clear sky, January scores 2.8 hours at Mäntsälä, 3rd of 12. Vantaa, 41 km away, averages the same 82%.

Civil night at Mäntsälä starts January at 16 h 2 min and reaches 14 h 25 min by January 31, 1.6 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 11.9 hours on the 15th.

January night by night

January opens toward a new moon on Jan 7, with full moon on Jan 22, in Europe/Helsinki dates. Mäntsälä gets 268 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: Jan 1 (4 h), Jan 2 (4 h), Jan 3 (4 h).

1
29% lit
12.1 h
2
21% lit
13.7 h
3
14% lit
15.2 h
4
8% lit
15.9 h
5
3% lit
15.9 h
6
1% lit
15.9 h
7
0% lit
15.8 h
New
8
1% lit
15.8 h
9
4% lit
15.2 h
10
8% lit
13.6 h
11
14% lit
12.2 h
12
22% lit
10.7 h
13
31% lit
9.3 h
14
40% lit
7.8 h
15
51% lit
6.2 h
16
62% lit
4.4 h
17
72% lit
2.6 h
18
82% lit
0.8 h
19
90% lit
0.0 h
20
96% lit
0.0 h
21
99% lit
0.0 h
22
100% lit
0.0 h
Full
23
97% lit
0.8 h
24
92% lit
2.5 h
25
84% lit
4.2 h
26
75% lit
5.8 h
27
66% lit
7.3 h
28
56% lit
8.9 h
29
46% lit
10.5 h
30
36% lit
12.1 h
31
27% lit
13.5 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 Januarys

Mäntsälä needs Kp 4 for the average oval edge to sit overhead. 196 of the 930 January days from 1996 to 2025 (21%) reached it in the GFZ Potsdam record, one of the three quietest months for that level; storm days with Kp 5 or more made up 6%. Mäntsälä sits at 58.1 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 4, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less.

January across Finland

Mäntsälä ranks 20th in Finland for civil night on January 15, behind Rovaniemi at 16.7 hours. Coming from December (16.1 hours at Mäntsälä), January loses darkness, and February brings shorter nights (13.2 hours on the 15th).

Civil night on January 15 and January cloud, month-page towns in Finland
Town	Civil night	Cloud
Rovaniemi	16.7 h	78%
Tornio	16.6 h	79%
Kemi	16.5 h	79%
Haukipudas	16.4 h	79%
Oulu	16.3 h	79%
Raahe	16.3 h	80%
Kajaani	16.2 h	76%
Kokkola	16.1 h	83%
Ylivieska	16.1 h	80%
Iisalmi	16.0 h	79%
Jakobstad	16.0 h	83%
Kuopio	15.9 h	80%
Mäntsälä	15.5 h	82%

Darkness and moon, every night

Mäntsälä, January 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
Fri Jan 1	16 h 2 min	12 h 24 min	12 h 5 min	4 h	29%
Sat Jan 2	16 h	12 h 22 min	13 h 40 min	4 h	21%
Sun Jan 3	15 h 58 min	12 h 21 min	15 h 13 min	4 h	14%
Mon Jan 4	15 h 56 min	12 h 19 min	15 h 56 min	4 h	8%
Tue Jan 5	15 h 54 min	12 h 18 min	15 h 54 min	4 h	3%
Wed Jan 6	15 h 52 min	12 h 16 min	15 h 52 min	4 h	1%
Thu Jan 7	15 h 50 min	12 h 14 min	15 h 50 min	4 h	0%
Fri Jan 8	15 h 47 min	12 h 12 min	15 h 47 min	4 h	1%
Sat Jan 9	15 h 45 min	12 h 10 min	15 h 9 min	4 h	4%
Sun Jan 10	15 h 42 min	12 h 8 min	13 h 38 min	4 h	8%
Mon Jan 11	15 h 39 min	12 h 6 min	12 h 10 min	4 h	14%
Tue Jan 12	15 h 37 min	12 h 3 min	10 h 43 min	4 h	22%
Wed Jan 13	15 h 34 min	12 h 1 min	9 h 16 min	3 h 2 min	31%
Thu Jan 14	15 h 31 min	11 h 59 min	7 h 45 min	1 h 33 min	40%
Fri Jan 15	15 h 27 min	11 h 56 min	6 h 9 min	0 min	51%
Sat Jan 16	15 h 24 min	11 h 53 min	4 h 26 min	0 min	62%
Sun Jan 17	15 h 21 min	11 h 50 min	2 h 36 min	0 min	72%
Mon Jan 18	15 h 17 min	11 h 47 min	49 min	0 min	82%
Tue Jan 19	15 h 14 min	11 h 45 min	0 min	0 min	90%
Wed Jan 20	15 h 10 min	11 h 41 min	0 min	0 min	96%
Thu Jan 21	15 h 6 min	11 h 38 min	0 min	0 min	99%
Fri Jan 22	15 h 2 min	11 h 35 min	0 min	0 min	100%
Sat Jan 23	14 h 58 min	11 h 32 min	46 min	0 min	97%
Sun Jan 24	14 h 54 min	11 h 28 min	2 h 32 min	0 min	92%
Mon Jan 25	14 h 50 min	11 h 25 min	4 h 11 min	0 min	84%
Tue Jan 26	14 h 46 min	11 h 21 min	5 h 46 min	54 min	75%
Wed Jan 27	14 h 42 min	11 h 18 min	7 h 20 min	2 h 29 min	66%
Thu Jan 28	14 h 38 min	11 h 14 min	8 h 53 min	4 h	56%
Fri Jan 29	14 h 34 min	11 h 10 min	10 h 28 min	4 h	46%
Sat Jan 30	14 h 29 min	11 h 6 min	12 h 3 min	4 h	36%
Sun Jan 31	14 h 25 min	11 h 2 min	13 h 31 min	4 h	27%

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

Questions

Can you see the northern lights in Mäntsälä in January?: On dark, clear nights with enough activity. 31 of 31 nights at Mäntsälä have civil darkness, and 21% of past January days reached Kp 4.
How dark is Mäntsälä in January?: Mäntsälä averages 15.3 hours of civil night a night in January 2027, from 16 h 2 min on the 1st to 14 h 25 min on the last night.
How cloudy is Mäntsälä in January?: NASA POWER's 2001 to 2020 climatology gives Mäntsälä's 1 degree cell 82% mean cloud in January, against 72% for the whole year. It is an all-hours average, not a forecast.
What is the best night in January 2027 for aurora in Mäntsälä?: By darkness and moon alone, Jan 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Mäntsälä. Activity on that date will only be known hours ahead.
Is January or February better in Mäntsälä?: By civil night times the clear share, January scores 2.8 hours at Mäntsälä and February 2.8. January 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.