Can you see the northern lights in Saint-Jérôme in May?

On dark, clear nights with enough activity. 31 of 31 nights at Saint-Jérôme have civil darkness, and 4% of past May days reached Kp 6.

How dark is Saint-Jérôme in May?

Saint-Jérôme averages 7.8 hours of civil night a night in May 2027, from 8 h 26 min on the 1st to 7 h 11 min on the last night.

How cloudy is Saint-Jérôme in May?

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

What is the best night in May 2027 for aurora in Saint-Jérôme?

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

Is May or June better in Saint-Jérôme?

By civil night times the clear share, May scores 2.8 hours at Saint-Jérôme and June 2.7. May comes out ahead.

Saint-Jérôme · May 2027

Northern lights in Saint-Jérôme in May 2027

Answer

May gives Saint-Jérôme 7.8 hours of civil night on the 15th, the 10th darkest of its 12 months, under 64% mean cloud. 4% of May days since 1996 reached Kp 6, enough for the oval edge to reach Saint-Jérôme.

7.8 h

civil night, average night

SunCalc for 45.78, -74.00; NASA POWER; GFZ Kp

May against the rest of the year

4.1

4.0

3.3

2.8

2.7

3.2

3.8

4.8

3.8

3.4

May cloud at Saint-Jérôme averages 64% in NASA POWER's 2001 to 2020 record, close to its yearly mean of 64%. September is Saint-Jérôme's clearest month at 54%. By civil night times clear sky, May scores 2.8 hours at Saint-Jérôme, 11th of 12. Trois-Rivières, 129 km away, averages 66%, cloudier by 2 points.

Civil night at Saint-Jérôme starts May at 8 h 26 min and reaches 7 h 11 min by May 31, 1.3 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 4.4 hours on the 15th.

May night by night

May opens toward a new moon on May 6, with full moon on May 20, in America/Toronto dates. Saint-Jérôme gets 122 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: May 1 (4 h), May 2 (4 h), May 3 (4 h).

1
20% lit
7.1 h
2
13% lit
7.3 h
3
6% lit
7.7 h
4
2% lit
8.0 h
5
0% lit
8.2 h
6
1% lit
7.9 h
New
7
4% lit
6.6 h
8
10% lit
5.5 h
9
18% lit
4.5 h
10
28% lit
3.8 h
11
38% lit
3.2 h
12
50% lit
2.7 h
13
61% lit
2.3 h
14
71% lit
2.0 h
15
81% lit
1.6 h
16
88% lit
1.3 h
17
94% lit
0.9 h
18
98% lit
0.4 h
19
100% lit
0.0 h
20
99% lit
0.3 h
Full
21
97% lit
1.3 h
22
93% lit
2.1 h
23
87% lit
2.7 h
24
80% lit
3.2 h
25
72% lit
3.6 h
26
64% lit
4.0 h
27
54% lit
4.3 h
28
44% lit
4.5 h
29
35% lit
4.8 h
30
25% lit
5.1 h
31
17% lit
5.4 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 Mays

Saint-Jérôme needs Kp 6 for the average oval edge to sit overhead. 39 of the 930 May days from 1996 to 2025 (4%) reached it in the GFZ Potsdam record, 4th of 12 months; storm days with Kp 5 or more made up 10%. Saint-Jérôme sits at 55.0 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.

May across Canada

No month-page town in Canada has more civil night on May 15 than Saint-Jérôme; the national median is 7.0 hours. Coming from April (9.3 hours at Saint-Jérôme), May loses darkness, and June brings shorter nights (6.9 hours on the 15th).

Civil night on May 15 and May cloud, month-page towns in Canada
Town	Civil night	Cloud
Saint-Jérôme	7.8 h	64%
Greater Sudbury	7.7 h	64%
Trois-Rivières	7.7 h	66%
Sydney	7.7 h	72%
Québec	7.6 h	69%
St. John's	7.5 h	77%
Saguenay	7.4 h	71%
Thunder Bay	7.4 h	73%
Lethbridge	7.2 h	65%
Winnipeg	7.1 h	60%
Kelowna	7.1 h	68%
Regina	7.0 h	62%

Darkness and moon, every night

Saint-Jérôme, May 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
Sat May 1	8 h 26 min	5 h 29 min	7 h 4 min	4 h	20%
Sun May 2	8 h 23 min	5 h 25 min	7 h 21 min	4 h	13%
Mon May 3	8 h 20 min	5 h 20 min	7 h 39 min	4 h	6%
Tue May 4	8 h 17 min	5 h 16 min	8 h	4 h	2%
Wed May 5	8 h 14 min	5 h 11 min	8 h 14 min	4 h	0%
Thu May 6	8 h 11 min	5 h 7 min	7 h 56 min	4 h	1%
Fri May 7	8 h 8 min	5 h 2 min	6 h 38 min	3 h 42 min	4%
Sat May 8	8 h 5 min	4 h 58 min	5 h 28 min	2 h 33 min	10%
Sun May 9	8 h 3 min	4 h 53 min	4 h 30 min	1 h 37 min	18%
Mon May 10	8 h	4 h 49 min	3 h 45 min	53 min	28%
Tue May 11	7 h 57 min	4 h 44 min	3 h 11 min	20 min	38%
Wed May 12	7 h 54 min	4 h 40 min	2 h 43 min	0 min	50%
Thu May 13	7 h 51 min	4 h 35 min	2 h 20 min	0 min	61%
Fri May 14	7 h 49 min	4 h 31 min	1 h 58 min	0 min	71%
Sat May 15	7 h 46 min	4 h 26 min	1 h 38 min	0 min	81%
Sun May 16	7 h 43 min	4 h 22 min	1 h 17 min	0 min	88%
Mon May 17	7 h 41 min	4 h 18 min	53 min	0 min	94%
Tue May 18	7 h 38 min	4 h 13 min	25 min	0 min	98%
Wed May 19	7 h 36 min	4 h 9 min	0 min	0 min	100%
Thu May 20	7 h 33 min	4 h 5 min	16 min	0 min	99%
Fri May 21	7 h 31 min	4 h	1 h 15 min	22 min	97%
Sat May 22	7 h 29 min	3 h 56 min	2 h 4 min	1 h 12 min	93%
Sun May 23	7 h 27 min	3 h 52 min	2 h 43 min	1 h 53 min	87%
Mon May 24	7 h 24 min	3 h 48 min	3 h 14 min	2 h 25 min	80%
Tue May 25	7 h 22 min	3 h 44 min	3 h 38 min	2 h 50 min	72%
Wed May 26	7 h 20 min	3 h 39 min	3 h 59 min	3 h 12 min	64%
Thu May 27	7 h 18 min	3 h 35 min	4 h 16 min	3 h 30 min	54%
Fri May 28	7 h 16 min	3 h 32 min	4 h 32 min	3 h 47 min	44%
Sat May 29	7 h 14 min	3 h 28 min	4 h 48 min	4 h	35%
Sun May 30	7 h 12 min	3 h 24 min	5 h 6 min	4 h	25%
Mon May 31	7 h 11 min	3 h 20 min	5 h 26 min	4 h	17%

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

Questions

Can you see the northern lights in Saint-Jérôme in May?: On dark, clear nights with enough activity. 31 of 31 nights at Saint-Jérôme have civil darkness, and 4% of past May days reached Kp 6.
How dark is Saint-Jérôme in May?: Saint-Jérôme averages 7.8 hours of civil night a night in May 2027, from 8 h 26 min on the 1st to 7 h 11 min on the last night.
How cloudy is Saint-Jérôme in May?: NASA POWER's 2001 to 2020 climatology gives Saint-Jérôme's 1 degree cell 64% mean cloud in May, against 64% for the whole year. It is an all-hours average, not a forecast.
What is the best night in May 2027 for aurora in Saint-Jérôme?: By darkness and moon alone, May 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Saint-Jérôme. Activity on that date will only be known hours ahead.
Is May or June better in Saint-Jérôme?: By civil night times the clear share, May scores 2.8 hours at Saint-Jérôme and June 2.7. May 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.