Can you see the northern lights in Ottawa South in July?

On dark, clear nights with enough activity. 31 of 31 nights at Ottawa South have civil darkness, and 3% of past July days reached Kp 6.

How dark is Ottawa South in July?

Ottawa South averages 7.4 hours of civil night a night in July 2027, from 7 h 2 min on the 1st to 8 h on the last night.

How cloudy is Ottawa South in July?

NASA POWER's 2001 to 2020 climatology gives Ottawa South's 1 degree cell 56% mean cloud in July, against 64% for the whole year. It is an all-hours average, not a forecast.

What is the best night in July 2027 for aurora in Ottawa South?

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

Is July or August better in Ottawa South?

By civil night times the clear share, July scores 3.3 hours at Ottawa South and August 3.9. August comes out ahead.

Ottawa South · July 2027

Northern lights in Ottawa South in July 2027

Answer

July gives Ottawa South 7.4 hours of civil night on the 15th, the 11th darkest of its 12 months, under 56% mean cloud. 3% of July days since 1996 reached Kp 6, enough for the oval edge to reach Ottawa South.

7.4 h

civil night, average night

SunCalc for 45.39, -75.69; NASA POWER; GFZ Kp

July against the rest of the year

4.1

4.0

3.3

2.8

2.7

3.3

3.9

4.8

3.8

3.7

3.4

July cloud at Ottawa South averages 56% in NASA POWER's 2001 to 2020 record, 8 points clearer than its yearly mean. September is Ottawa South's clearest month at 54%. By civil night times clear sky, July scores 3.3 hours at Ottawa South, 9th of 12. Trois-Rivières, 265 km away, averages 60%, cloudier by 4 points.

Civil night at Ottawa South starts July at 7 h 2 min and reaches 8 h by July 31 as the nights lengthen by 1.0 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 3.8 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/Toronto dates. Ottawa South gets 110 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
5.6 h
2
1% lit
6.7 h
3
0% lit
7.1 h
New
4
2% lit
7.0 h
5
6% lit
6.5 h
6
13% lit
6.0 h
7
22% lit
5.6 h
8
33% lit
5.3 h
9
43% lit
5.0 h
10
54% lit
4.6 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
0.0 h
20
94% lit
0.4 h
21
89% lit
0.7 h
22
83% lit
1.0 h
23
75% lit
1.3 h
24
66% lit
1.6 h
25
56% lit
2.0 h
26
45% lit
2.5 h
27
35% lit
3.0 h
28
24% lit
3.8 h
29
15% lit
4.7 h
30
8% lit
6.0 h
31
2% lit
7.3 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

Ottawa South needs Kp 6 for the average oval edge to sit overhead. 26 of the 930 July days from 1996 to 2025 (3%) reached it in the GFZ Potsdam record, 9th of 12 months; storm days with Kp 5 or more made up 9%. Ottawa South sits at 54.6 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 6.

July across Canada

No month-page town in Canada has more civil night on July 15 than Ottawa South; the national median is 6.5 hours. Coming from June (7.0 hours at Ottawa South), July adds darkness, and the nights keep growing into August (8.8 hours on the 15th).

Civil night on July 15 and July cloud, month-page towns in Canada
Town	Civil night	Cloud
Ottawa South	7.4 h	56%
Sydney	7.3 h	66%
Québec	7.2 h	62%
Greater Sudbury	7.2 h	54%
Trois-Rivières	7.2 h	60%
St. John's	7.0 h	73%
Saguenay	6.9 h	70%
Thunder Bay	6.9 h	65%
Winnipeg	6.6 h	50%
Kelowna	6.6 h	44%
Lethbridge	6.6 h	42%
Regina	6.5 h	49%

Darkness and moon, every night

Ottawa South, 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 2 min	3 h 2 min	5 h 38 min	4 h	6%
Fri Jul 2	7 h 3 min	3 h 4 min	6 h 44 min	4 h	1%
Sat Jul 3	7 h 4 min	3 h 7 min	7 h 4 min	4 h	0%
Sun Jul 4	7 h 5 min	3 h 9 min	7 h	4 h	2%
Mon Jul 5	7 h 6 min	3 h 12 min	6 h 27 min	3 h 46 min	6%
Tue Jul 6	7 h 7 min	3 h 15 min	6 h	3 h 19 min	13%
Wed Jul 7	7 h 9 min	3 h 18 min	5 h 38 min	2 h 56 min	22%
Thu Jul 8	7 h 10 min	3 h 21 min	5 h 18 min	2 h 35 min	33%
Fri Jul 9	7 h 12 min	3 h 24 min	4 h 59 min	2 h 15 min	43%
Sat Jul 10	7 h 13 min	3 h 27 min	4 h 38 min	1 h 53 min	54%
Sun Jul 11	7 h 15 min	3 h 30 min	4 h 15 min	1 h 29 min	65%
Mon Jul 12	7 h 16 min	3 h 34 min	3 h 48 min	1 h 1 min	74%
Tue Jul 13	7 h 18 min	3 h 37 min	3 h 14 min	26 min	82%
Wed Jul 14	7 h 20 min	3 h 41 min	2 h 31 min	0 min	89%
Thu Jul 15	7 h 22 min	3 h 45 min	1 h 41 min	0 min	94%
Fri Jul 16	7 h 24 min	3 h 49 min	43 min	0 min	98%
Sat Jul 17	7 h 26 min	3 h 52 min	0 min	0 min	100%
Sun Jul 18	7 h 28 min	3 h 56 min	0 min	0 min	100%
Mon Jul 19	7 h 30 min	4 h	2 min	0 min	98%
Tue Jul 20	7 h 33 min	4 h 4 min	24 min	0 min	94%
Wed Jul 21	7 h 35 min	4 h 8 min	43 min	5 min	89%
Thu Jul 22	7 h 37 min	4 h 13 min	1 h 1 min	22 min	83%
Fri Jul 23	7 h 40 min	4 h 17 min	1 h 19 min	39 min	75%
Sat Jul 24	7 h 42 min	4 h 21 min	1 h 39 min	57 min	66%
Sun Jul 25	7 h 44 min	4 h 25 min	2 h 1 min	1 h 18 min	56%
Mon Jul 26	7 h 47 min	4 h 29 min	2 h 27 min	1 h 43 min	45%
Tue Jul 27	7 h 49 min	4 h 33 min	3 h 1 min	2 h 16 min	35%
Wed Jul 28	7 h 52 min	4 h 38 min	3 h 46 min	2 h 59 min	24%
Thu Jul 29	7 h 55 min	4 h 42 min	4 h 44 min	3 h 56 min	15%
Fri Jul 30	7 h 57 min	4 h 46 min	5 h 57 min	4 h	8%
Sat Jul 31	8 h	4 h 51 min	7 h 20 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 Ottawa South in July?: On dark, clear nights with enough activity. 31 of 31 nights at Ottawa South have civil darkness, and 3% of past July days reached Kp 6.
How dark is Ottawa South in July?: Ottawa South averages 7.4 hours of civil night a night in July 2027, from 7 h 2 min on the 1st to 8 h on the last night.
How cloudy is Ottawa South in July?: NASA POWER's 2001 to 2020 climatology gives Ottawa South's 1 degree cell 56% mean cloud in July, against 64% for the whole year. It is an all-hours average, not a forecast.
What is the best night in July 2027 for aurora in Ottawa South?: By darkness and moon alone, Jul 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Ottawa South. Activity on that date will only be known hours ahead.
Is July or August better in Ottawa South?: By civil night times the clear share, July scores 3.3 hours at Ottawa South and August 3.9. 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.