Ushuaia · September 2027
Southern lights in Ushuaia in September 2027
Answer
September against the rest of the year
September cloud at Ushuaia averages 77% in NASA POWER's 2001 to 2020 record, close to its yearly mean of 78%. July is Ushuaia's clearest month at 72%. By civil night times clear sky, September scores 2.5 hours at Ushuaia, 6th of 12. Buffalo, 10,909 km away, averages 57%, clearer by 20 points.
Civil night at Ushuaia starts September at 12 h 1 min and reaches 9 h 53 min by September 30, 2.1 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 8.1 hours on the 15th.
September night by night
Full moon comes first, on Sep 15, then the new moon on Sep 29, in America/Argentina/Ushuaia dates. Ushuaia gets 159 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: Sep 1 (4 h), Sep 20 (4 h), Sep 21 (4 h).
- 1
3% lit
10.9 h
- 2
8% lit
9.3 h
- 3
15% lit
7.8 h
- 4
24% lit
6.3 h
- 5
34% lit
4.8 h
- 6
44% lit
3.5 h
- 7
54% lit
2.5 h
- 8
63% lit
1.7 h
- 9
72% lit
1.1 h
- 10
80% lit
0.7 h
- 11
87% lit
0.4 h
- 12
93% lit
0.2 h
- 13
97% lit
0.0 h
- 14
99% lit
0.0 h
- 15
100% lit
0.0 h
- 16
99% lit
0.7 h
- 17
95% lit
2.0 h
- 18
90% lit
3.3 h
- 19
83% lit
4.7 h
- 20
74% lit
6.0 h
- 21
64% lit
7.3 h
- 22
54% lit
8.3 h
- 23
42% lit
9.0 h
- 24
31% lit
9.4 h
- 25
21% lit
9.7 h
- 26
12% lit
9.9 h
- 27
6% lit
10.1 h
- 28
1% lit
10.0 h
- 29
0% lit
10.0 h
- 30
2% lit
9.2 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 Septembers
No whole Kp puts the average oval edge over Ushuaia by SWPC's rule, so the GFZ record has no threshold to count for September. Ushuaia sits at 45.6 degrees geomagnetic. The lowest NOAA storm level whose typical viewing latitude reaches it is G4 (Kp = 8, including a 9-). Even Kp 9 does not put the average oval edge overhead by SWPC's rule.
September across Argentina
Coming from August (13.1 hours at Ushuaia), September loses darkness, and October brings shorter nights (8.7 hours on the 15th). The September equinox falls on September 23, 02:56 Ushuaia time, inside the weeks SWPC links with larger storms.
Darkness and moon, every night
| Night | Civil | Astronomical | Moon-free dark | Moon-free, 10 PM to 2 AM | Moon lit |
|---|---|---|---|---|---|
| Wed Sep 1 | 12 h 1 min | 9 h 13 min | 10 h 53 min | 4 h | 3% |
| Thu Sep 2 | 11 h 56 min | 9 h 9 min | 9 h 20 min | 3 h 49 min | 8% |
| Fri Sep 3 | 11 h 52 min | 9 h 4 min | 7 h 47 min | 2 h 19 min | 15% |
| Sat Sep 4 | 11 h 48 min | 9 h | 6 h 17 min | 51 min | 24% |
| Sun Sep 5 | 11 h 44 min | 8 h 56 min | 4 h 51 min | 0 min | 34% |
| Mon Sep 6 | 11 h 40 min | 8 h 51 min | 3 h 33 min | 0 min | 44% |
| Tue Sep 7 | 11 h 35 min | 8 h 47 min | 2 h 29 min | 0 min | 54% |
| Wed Sep 8 | 11 h 31 min | 8 h 42 min | 1 h 41 min | 0 min | 63% |
| Thu Sep 9 | 11 h 27 min | 8 h 37 min | 1 h 7 min | 0 min | 72% |
| Fri Sep 10 | 11 h 23 min | 8 h 33 min | 42 min | 0 min | 80% |
| Sat Sep 11 | 11 h 18 min | 8 h 28 min | 24 min | 0 min | 87% |
| Sun Sep 12 | 11 h 14 min | 8 h 23 min | 10 min | 0 min | 93% |
| Mon Sep 13 | 11 h 10 min | 8 h 19 min | 0 min | 0 min | 97% |
| Tue Sep 14 | 11 h 5 min | 8 h 14 min | 0 min | 0 min | 99% |
| Wed Sep 15 | 11 h 1 min | 8 h 9 min | 0 min | 0 min | 100% |
| Thu Sep 16 | 10 h 56 min | 8 h 4 min | 43 min | 0 min | 99% |
| Fri Sep 17 | 10 h 52 min | 7 h 59 min | 1 h 59 min | 0 min | 95% |
| Sat Sep 18 | 10 h 48 min | 7 h 54 min | 3 h 19 min | 1 h 22 min | 90% |
| Sun Sep 19 | 10 h 43 min | 7 h 49 min | 4 h 41 min | 2 h 46 min | 83% |
| Mon Sep 20 | 10 h 39 min | 7 h 44 min | 6 h 3 min | 4 h | 74% |
| Tue Sep 21 | 10 h 34 min | 7 h 38 min | 7 h 18 min | 4 h | 64% |
| Wed Sep 22 | 10 h 30 min | 7 h 33 min | 8 h 18 min | 4 h | 54% |
| Thu Sep 23 | 10 h 25 min | 7 h 28 min | 8 h 59 min | 4 h | 42% |
| Fri Sep 24 | 10 h 21 min | 7 h 23 min | 9 h 25 min | 4 h | 31% |
| Sat Sep 25 | 10 h 16 min | 7 h 17 min | 9 h 42 min | 4 h | 21% |
| Sun Sep 26 | 10 h 12 min | 7 h 12 min | 9 h 54 min | 4 h | 12% |
| Mon Sep 27 | 10 h 7 min | 7 h 6 min | 10 h 4 min | 4 h | 6% |
| Tue Sep 28 | 10 h 2 min | 7 h | 10 h 2 min | 4 h | 1% |
| Wed Sep 29 | 9 h 58 min | 6 h 55 min | 9 h 58 min | 4 h | 0% |
| Thu Sep 30 | 9 h 53 min | 6 h 49 min | 9 h 12 min | 4 h | 2% |
Questions
- Can you see the southern lights in Ushuaia in September?
- On dark, clear nights with enough activity. 30 of 30 nights at Ushuaia have civil darkness.
- How dark is Ushuaia in September?
- Ushuaia averages 11.0 hours of civil night a night in September 2027, from 12 h 1 min on the 1st to 9 h 53 min on the last night.
- How cloudy is Ushuaia in September?
- NASA POWER's 2001 to 2020 climatology gives Ushuaia's 1 degree cell 77% mean cloud in September, against 78% for the whole year. It is an all-hours average, not a forecast.
- What is the best night in September 2027 for aurora in Ushuaia?
- By darkness and moon alone, Sep 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Ushuaia. Activity on that date will only be known hours ahead.
- Is September or October better in Ushuaia?
- By civil night times the clear share, September scores 2.5 hours at Ushuaia and October 1.7. September 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.