Can you see the northern lights in Lethbridge in May?

On dark, clear nights with enough activity. 31 of 31 nights at Lethbridge have civil darkness, and 10% of past May days reached Kp 5.

How dark is Lethbridge in May?

Lethbridge averages 7.1 hours of civil night a night in May 2027, from 7 h 58 min on the 1st to 6 h 26 min on the last night.

How cloudy is Lethbridge in May?

NASA POWER's 2001 to 2020 climatology gives Lethbridge's 1 degree cell 65% mean cloud in May, against 63% for the whole year. It is an all-hours average, not a forecast.

What is the best night in May 2027 for aurora in Lethbridge?

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

Is May or June better in Lethbridge?

By civil night times the clear share, May scores 2.5 hours at Lethbridge and June 2.4. May comes out ahead.

Lethbridge · May 2027

Northern lights in Lethbridge in May 2027

Answer

May gives Lethbridge 7.2 hours of civil night on the 15th, the 10th darkest of its 12 months, under 65% mean cloud. 10% of May days since 1996 reached Kp 5, enough for the oval edge to reach Lethbridge.

7.1 h

civil night, average night

SunCalc for 49.70, -112.82; NASA POWER; GFZ Kp

May against the rest of the year

4.1

3.9

3.4

2.9

2.5

2.4

3.8

4.1

4.5

4.2

4.5

May cloud at Lethbridge averages 65% in NASA POWER's 2001 to 2020 record, 2 points cloudier than its yearly mean. July is Lethbridge's clearest month at 42%. By civil night times clear sky, May scores 2.5 hours at Lethbridge, 11th of 12. Calgary, 175 km away, averages 70%, cloudier by 5 points.

Civil night at Lethbridge starts May at 7 h 58 min and reaches 6 h 26 min by May 31, 1.5 hours shorter. The 10 PM to 2 AM window is fully dark on 20 of 31 nights. True astronomical darkness, the sun 18 degrees down, lasts 2.9 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/Edmonton dates. Lethbridge gets 113 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
19% lit
6.9 h
2
12% lit
7.1 h
3
6% lit
7.3 h
4
2% lit
7.6 h
5
0% lit
7.7 h
6
1% lit
7.2 h
New
7
4% lit
5.9 h
8
10% lit
4.7 h
9
19% lit
3.8 h
10
28% lit
3.1 h
11
39% lit
2.6 h
12
51% lit
2.3 h
13
62% lit
1.9 h
14
72% lit
1.6 h
15
81% lit
1.4 h
16
89% lit
1.1 h
17
95% lit
0.7 h
18
98% lit
0.3 h
19
100% lit
0.0 h
20
99% lit
0.4 h
Full
21
97% lit
1.4 h
22
92% lit
2.2 h
23
87% lit
2.8 h
24
80% lit
3.2 h
25
72% lit
3.5 h
26
63% lit
3.8 h
27
53% lit
4.0 h
28
44% lit
4.2 h
29
34% lit
4.5 h
30
25% lit
4.7 h
31
16% lit
5.0 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

Lethbridge needs Kp 5 for the average oval edge to sit overhead. 97 of the 930 May days from 1996 to 2025 (10%) reached it in the GFZ Potsdam record, 6th of 12 months; storm days with Kp 5 or more made up 10%. Lethbridge sits at 56.3 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 5, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less.

May across Canada

Lethbridge ranks 8th in Canada for civil night on May 15, behind Greater Sudbury at 7.7 hours. Coming from April (9.0 hours at Lethbridge), May loses darkness, and June brings shorter nights (6.1 hours on the 15th).

Civil night on May 15 and May cloud, month-page towns in Canada
Town	Civil night	Cloud
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%
Kamloops	7.0 h	70%

Darkness and moon, every night

Lethbridge, 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	7 h 58 min	4 h 30 min	6 h 53 min	4 h	19%
Sun May 2	7 h 54 min	4 h 24 min	7 h 5 min	4 h	12%
Mon May 3	7 h 50 min	4 h 17 min	7 h 19 min	4 h	6%
Tue May 4	7 h 47 min	4 h 11 min	7 h 37 min	4 h	2%
Wed May 5	7 h 43 min	4 h 5 min	7 h 43 min	4 h	0%
Thu May 6	7 h 40 min	3 h 59 min	7 h 14 min	3 h 56 min	1%
Fri May 7	7 h 36 min	3 h 52 min	5 h 53 min	2 h 37 min	4%
Sat May 8	7 h 33 min	3 h 46 min	4 h 43 min	1 h 29 min	10%
Sun May 9	7 h 29 min	3 h 39 min	3 h 48 min	36 min	19%
Mon May 10	7 h 26 min	3 h 32 min	3 h 8 min	0 min	28%
Tue May 11	7 h 22 min	3 h 25 min	2 h 38 min	0 min	39%
Wed May 12	7 h 19 min	3 h 19 min	2 h 15 min	0 min	51%
Thu May 13	7 h 16 min	3 h 11 min	1 h 56 min	0 min	62%
Fri May 14	7 h 13 min	3 h 4 min	1 h 38 min	0 min	72%
Sat May 15	7 h 9 min	2 h 57 min	1 h 21 min	0 min	81%
Sun May 16	7 h 6 min	2 h 50 min	1 h 4 min	0 min	89%
Mon May 17	7 h 3 min	2 h 42 min	43 min	0 min	95%
Tue May 18	7 h	2 h 34 min	19 min	0 min	98%
Wed May 19	6 h 57 min	2 h 26 min	0 min	0 min	100%
Thu May 20	6 h 54 min	2 h 18 min	25 min	25 min	99%
Fri May 21	6 h 51 min	2 h 9 min	1 h 24 min	1 h 24 min	97%
Sat May 22	6 h 48 min	2 h	2 h 11 min	2 h 11 min	92%
Sun May 23	6 h 46 min	1 h 51 min	2 h 46 min	2 h 46 min	87%
Mon May 24	6 h 43 min	1 h 41 min	3 h 13 min	3 h 13 min	80%
Tue May 25	6 h 40 min	1 h 31 min	3 h 33 min	3 h 33 min	72%
Wed May 26	6 h 38 min	1 h 19 min	3 h 49 min	3 h 49 min	63%
Thu May 27	6 h 35 min	1 h 6 min	4 h 2 min	3 h 49 min	53%
Fri May 28	6 h 33 min	50 min	4 h 14 min	3 h 48 min	44%
Sat May 29	6 h 31 min	27 min	4 h 27 min	3 h 47 min	34%
Sun May 30	6 h 28 min	0 min	4 h 41 min	3 h 45 min	25%
Mon May 31	6 h 26 min	0 min	4 h 57 min	3 h 44 min	16%

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

Questions

Can you see the northern lights in Lethbridge in May?: On dark, clear nights with enough activity. 31 of 31 nights at Lethbridge have civil darkness, and 10% of past May days reached Kp 5.
How dark is Lethbridge in May?: Lethbridge averages 7.1 hours of civil night a night in May 2027, from 7 h 58 min on the 1st to 6 h 26 min on the last night.
How cloudy is Lethbridge in May?: NASA POWER's 2001 to 2020 climatology gives Lethbridge's 1 degree cell 65% mean cloud in May, against 63% for the whole year. It is an all-hours average, not a forecast.
What is the best night in May 2027 for aurora in Lethbridge?: By darkness and moon alone, May 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Lethbridge. Activity on that date will only be known hours ahead.
Is May or June better in Lethbridge?: By civil night times the clear share, May scores 2.5 hours at Lethbridge and June 2.4. 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.