Cork · May 2027
Northern lights in Cork in May 2027
Answer
May against the rest of the year
May cloud at Cork averages 69% in NASA POWER's 2001 to 2020 record, close to its yearly mean of 70%. April is Cork's clearest month at 66%. By civil night times clear sky, May scores 2.1 hours at Cork, 10th of 12. Limerick, 86 km away, averages 76%, cloudier by 7 points.
Civil night at Cork starts May at 7 h 40 min and reaches 5 h 56 min by May 31, 1.7 hours shorter. The 10 PM to 2 AM window is fully dark on 11 of 31 nights. True astronomical darkness, the sun 18 degrees down, lasts 1.4 hours on the 15th.
May night by night
May opens toward a new moon on May 6, with full moon on May 20, in Europe/Dublin dates. Cork gets 107 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
22% lit
6.7 h
- 2
14% lit
6.8 h
- 3
8% lit
7.0 h
- 4
3% lit
7.3 h
- 5
1% lit
7.4 h
- 6
1% lit
7.3 h
- 7
3% lit
5.8 h
- 8
8% lit
4.6 h
- 9
16% lit
3.6 h
- 10
25% lit
2.9 h
- 11
36% lit
2.4 h
- 12
47% lit
2.1 h
- 13
59% lit
1.8 h
- 14
69% lit
1.5 h
- 15
79% lit
1.3 h
- 16
87% lit
1.0 h
- 17
93% lit
0.7 h
- 18
97% lit
0.4 h
- 19
100% lit
0.0 h
- 20
100% lit
0.1 h
- 21
98% lit
1.2 h
- 22
94% lit
2.0 h
- 23
89% lit
2.6 h
- 24
82% lit
3.0 h
- 25
74% lit
3.4 h
- 26
65% lit
3.6 h
- 27
56% lit
3.8 h
- 28
46% lit
4.0 h
- 29
37% lit
4.1 h
- 30
27% lit
4.3 h
- 31
18% lit
4.5 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 Mays
Cork 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%. Cork sits at 55.0 degrees geomagnetic. By SWPC's rule the average oval edge is overhead at Kp 6, and aurora is usually visible on the northern horizon at G1 (Kp 5) or less.
May across Ireland
No month-page town in Ireland has more civil night on May 15 than Cork; the national median is 6.6 hours. Coming from April (8.8 hours at Cork), May loses darkness, and June brings shorter nights (5.5 hours on the 15th).
Darkness and moon, every night
| Night | Civil | Astronomical | Moon-free dark | Moon-free, 10 PM to 2 AM | Moon lit |
|---|---|---|---|---|---|
| Sat May 1 | 7 h 40 min | 3 h 47 min | 6 h 41 min | 4 h | 22% |
| Sun May 2 | 7 h 36 min | 3 h 39 min | 6 h 50 min | 4 h | 14% |
| Mon May 3 | 7 h 32 min | 3 h 31 min | 7 h 2 min | 4 h | 8% |
| Tue May 4 | 7 h 28 min | 3 h 23 min | 7 h 15 min | 4 h | 3% |
| Wed May 5 | 7 h 24 min | 3 h 14 min | 7 h 24 min | 4 h | 1% |
| Thu May 6 | 7 h 20 min | 3 h 6 min | 7 h 17 min | 4 h | 1% |
| Fri May 7 | 7 h 16 min | 2 h 57 min | 5 h 51 min | 2 h 43 min | 3% |
| Sat May 8 | 7 h 12 min | 2 h 48 min | 4 h 36 min | 1 h 30 min | 8% |
| Sun May 9 | 7 h 8 min | 2 h 38 min | 3 h 38 min | 33 min | 16% |
| Mon May 10 | 7 h 4 min | 2 h 28 min | 2 h 56 min | 0 min | 25% |
| Tue May 11 | 7 h 1 min | 2 h 17 min | 2 h 26 min | 0 min | 36% |
| Wed May 12 | 6 h 57 min | 2 h 6 min | 2 h 4 min | 0 min | 47% |
| Thu May 13 | 6 h 53 min | 1 h 54 min | 1 h 46 min | 0 min | 59% |
| Fri May 14 | 6 h 50 min | 1 h 41 min | 1 h 31 min | 0 min | 69% |
| Sat May 15 | 6 h 46 min | 1 h 25 min | 1 h 16 min | 0 min | 79% |
| Sun May 16 | 6 h 42 min | 1 h 8 min | 1 h 1 min | 0 min | 87% |
| Mon May 17 | 6 h 39 min | 43 min | 44 min | 0 min | 93% |
| Tue May 18 | 6 h 35 min | 0 min | 23 min | 0 min | 97% |
| Wed May 19 | 6 h 32 min | 0 min | 0 min | 0 min | 100% |
| Thu May 20 | 6 h 29 min | 0 min | 7 min | 7 min | 100% |
| Fri May 21 | 6 h 25 min | 0 min | 1 h 10 min | 1 h 10 min | 98% |
| Sat May 22 | 6 h 22 min | 0 min | 2 h | 2 h | 94% |
| Sun May 23 | 6 h 19 min | 0 min | 2 h 37 min | 2 h 37 min | 89% |
| Mon May 24 | 6 h 16 min | 0 min | 3 h 3 min | 3 h 3 min | 82% |
| Tue May 25 | 6 h 13 min | 0 min | 3 h 22 min | 3 h 22 min | 74% |
| Wed May 26 | 6 h 10 min | 0 min | 3 h 36 min | 3 h 34 min | 65% |
| Thu May 27 | 6 h 7 min | 0 min | 3 h 48 min | 3 h 33 min | 56% |
| Fri May 28 | 6 h 4 min | 0 min | 3 h 58 min | 3 h 31 min | 46% |
| Sat May 29 | 6 h 2 min | 0 min | 4 h 8 min | 3 h 30 min | 37% |
| Sun May 30 | 5 h 59 min | 0 min | 4 h 19 min | 3 h 28 min | 27% |
| Mon May 31 | 5 h 56 min | 0 min | 4 h 32 min | 3 h 27 min | 18% |
Questions
- Can you see the northern lights in Cork in May?
- On dark, clear nights with enough activity. 31 of 31 nights at Cork have civil darkness, and 4% of past May days reached Kp 6.
- How dark is Cork in May?
- Cork averages 6.7 hours of civil night a night in May 2027, from 7 h 40 min on the 1st to 5 h 56 min on the last night.
- How cloudy is Cork in May?
- NASA POWER's 2001 to 2020 climatology gives Cork's 1 degree cell 69% mean cloud in May, against 70% for the whole year. It is an all-hours average, not a forecast.
- What is the best night in May 2027 for aurora in Cork?
- By darkness and moon alone, May 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Cork. Activity on that date will only be known hours ahead.
- Is May or June better in Cork?
- By civil night times the clear share, May scores 2.1 hours at Cork and June 1.7. 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.