Can you see the northern lights in Somerville in July?

On dark, clear nights with enough activity. 31 of 31 nights at Somerville have civil darkness, and 0% of past July days reached Kp 8.

How dark is Somerville in July?

Somerville averages 7.9 hours of civil night a night in July 2027, from 7 h 31 min on the 1st to 8 h 22 min on the last night.

How cloudy is Somerville in July?

NASA POWER's 2001 to 2020 climatology gives Somerville's 1 degree cell 55% mean cloud in July, against 59% for the whole year. It is an all-hours average, not a forecast.

What is the best night in July 2027 for aurora in Somerville?

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

Is July or August better in Somerville?

By civil night times the clear share, July scores 3.5 hours at Somerville and August 4.2. August comes out ahead.

Somerville · July 2027

Northern lights in Somerville in July 2027

Answer

July gives Somerville 7.8 hours of civil night on the 15th, the 11th darkest of its 12 months, under 55% mean cloud. 0% of July days since 1996 reached Kp 8, enough for the oval edge to reach Somerville.

7.9 h

civil night, average night

SunCalc for 42.39, -71.10; NASA POWER; GFZ Kp

July against the rest of the year

5.1

4.8

4.3

3.7

3.0

2.9

3.5

4.2

5.1

4.9

5.2

5.1

July cloud at Somerville averages 55% in NASA POWER's 2001 to 2020 record, 4 points clearer than its yearly mean. September is Somerville's clearest month at 51%. By civil night times clear sky, July scores 3.5 hours at Somerville, 10th of 12. Portland, Maine, 157 km away, averages the same 55%.

Civil night at Somerville starts July at 7 h 31 min and reaches 8 h 22 min by July 31 as the nights lengthen by 0.8 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 4.7 hours on the 15th.

July night by night

July opens toward a new moon on Jul 3, with full moon on Jul 18, in America/New_York dates. Somerville gets 117 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: Jul 1 (4 h), Jul 2 (4 h), Jul 3 (4 h).

1
6% lit
6.1 h
2
1% lit
7.2 h
3
0% lit
7.5 h
New
4
2% lit
7.4 h
5
6% lit
6.8 h
6
13% lit
6.3 h
7
22% lit
5.9 h
8
33% lit
5.5 h
9
43% lit
5.2 h
10
54% lit
4.8 h
11
65% lit
4.3 h
12
74% lit
3.8 h
13
82% lit
3.2 h
14
89% lit
2.5 h
15
94% lit
1.7 h
16
98% lit
0.7 h
17
100% lit
0.0 h
18
100% lit
0.0 h
Full
19
98% lit
0.1 h
20
94% lit
0.5 h
21
89% lit
0.9 h
22
83% lit
1.2 h
23
75% lit
1.6 h
24
66% lit
1.9 h
25
56% lit
2.3 h
26
45% lit
2.8 h
27
35% lit
3.4 h
28
24% lit
4.2 h
29
15% lit
5.1 h
30
8% lit
6.3 h
31
2% lit
7.7 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 Julys

Somerville needs Kp 8 for the average oval edge to sit overhead. 3 of the 930 July days from 1996 to 2025 (0%) reached it in the GFZ Potsdam record, 7th of 12 months; storm days with Kp 5 or more made up 9%. Somerville sits at 51.6 degrees geomagnetic. The lowest NOAA storm level whose typical viewing latitude reaches it is G3 (Kp = 7). By SWPC's rule the average oval edge is overhead only at Kp 8.

July across United States

No month-page town in United States has more civil night on July 15 than Somerville; the national median is 7.1 hours. Coming from June (7.5 hours at Somerville), July adds darkness, and the nights keep growing into August (9.0 hours on the 15th).

Civil night on July 15 and July cloud, month-page towns in United States
Town	Civil night	Cloud
Somerville	7.8 h	55%
Buffalo	7.8 h	56%
Portland, Maine	7.6 h	55%
Minneapolis	7.4 h	46%
Duluth	7.2 h	51%
Fargo	7.1 h	48%
Seattle	7.0 h	47%
Juneau	4.1 h	81%
Anchorage	2.1 h	83%
Eagle River	2.0 h	83%
Fairbanks	0.0 h	77%

Darkness and moon, every night

Somerville, July 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 Jul 1	7 h 31 min	4 h 10 min	6 h 5 min	4 h	6%
Fri Jul 2	7 h 31 min	4 h 12 min	7 h 11 min	4 h	1%
Sat Jul 3	7 h 32 min	4 h 13 min	7 h 32 min	4 h	0%
Sun Jul 4	7 h 33 min	4 h 15 min	7 h 25 min	4 h	2%
Mon Jul 5	7 h 34 min	4 h 17 min	6 h 49 min	4 h	6%
Tue Jul 6	7 h 35 min	4 h 19 min	6 h 19 min	3 h 42 min	13%
Wed Jul 7	7 h 37 min	4 h 21 min	5 h 54 min	3 h 17 min	22%
Thu Jul 8	7 h 38 min	4 h 23 min	5 h 32 min	2 h 53 min	33%
Fri Jul 9	7 h 39 min	4 h 25 min	5 h 10 min	2 h 30 min	43%
Sat Jul 10	7 h 41 min	4 h 27 min	4 h 46 min	2 h 6 min	54%
Sun Jul 11	7 h 42 min	4 h 30 min	4 h 21 min	1 h 39 min	65%
Mon Jul 12	7 h 44 min	4 h 32 min	3 h 50 min	1 h 8 min	74%
Tue Jul 13	7 h 45 min	4 h 35 min	3 h 14 min	31 min	82%
Wed Jul 14	7 h 47 min	4 h 38 min	2 h 31 min	0 min	89%
Thu Jul 15	7 h 48 min	4 h 40 min	1 h 40 min	0 min	94%
Fri Jul 16	7 h 50 min	4 h 43 min	43 min	0 min	98%
Sat Jul 17	7 h 52 min	4 h 46 min	0 min	0 min	100%
Sun Jul 18	7 h 54 min	4 h 49 min	0 min	0 min	100%
Mon Jul 19	7 h 56 min	4 h 52 min	7 min	0 min	98%
Tue Jul 20	7 h 58 min	4 h 55 min	31 min	0 min	94%
Wed Jul 21	7 h 59 min	4 h 58 min	52 min	0 min	89%
Thu Jul 22	8 h 2 min	5 h 1 min	1 h 12 min	3 min	83%
Fri Jul 23	8 h 4 min	5 h 5 min	1 h 33 min	22 min	75%
Sat Jul 24	8 h 6 min	5 h 8 min	1 h 54 min	43 min	66%
Sun Jul 25	8 h 8 min	5 h 11 min	2 h 19 min	1 h 6 min	56%
Mon Jul 26	8 h 10 min	5 h 15 min	2 h 47 min	1 h 34 min	45%
Tue Jul 27	8 h 12 min	5 h 18 min	3 h 23 min	2 h 8 min	35%
Wed Jul 28	8 h 15 min	5 h 21 min	4 h 9 min	2 h 53 min	24%
Thu Jul 29	8 h 17 min	5 h 25 min	5 h 8 min	3 h 51 min	15%
Fri Jul 30	8 h 19 min	5 h 28 min	6 h 20 min	4 h	8%
Sat Jul 31	8 h 22 min	5 h 32 min	7 h 41 min	4 h	2%

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

Questions

Can you see the northern lights in Somerville in July?: On dark, clear nights with enough activity. 31 of 31 nights at Somerville have civil darkness, and 0% of past July days reached Kp 8.
How dark is Somerville in July?: Somerville averages 7.9 hours of civil night a night in July 2027, from 7 h 31 min on the 1st to 8 h 22 min on the last night.
How cloudy is Somerville in July?: NASA POWER's 2001 to 2020 climatology gives Somerville's 1 degree cell 55% mean cloud in July, against 59% for the whole year. It is an all-hours average, not a forecast.
What is the best night in July 2027 for aurora in Somerville?: By darkness and moon alone, Jul 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Somerville. Activity on that date will only be known hours ahead.
Is July or August better in Somerville?: By civil night times the clear share, July scores 3.5 hours at Somerville and August 4.2. August 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.