Arlington Heights · August 2027
Northern lights in Arlington Heights in August 2027
Answer
August against the rest of the year
August cloud at Arlington Heights averages 67% in NASA POWER's 2001 to 2020 record, 7 points clearer than its yearly mean. September is Arlington Heights's clearest month at 59%. By civil night times clear sky, August scores 3.0 hours at Arlington Heights, 7th of 12. Minneapolis, 533 km away, averages 49%, clearer by 18 points.
Civil night at Arlington Heights starts August at 8 h 26 min and reaches 9 h 47 min by August 31 as the nights lengthen by 1.4 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 6.5 hours on the 15th.
August night by night
August opens toward a new moon on Aug 2 and Aug 31, with full moon on Aug 17, in America/Chicago dates. Arlington Heights gets 142 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: Aug 1 (4 h), Aug 2 (4 h), Aug 3 (4 h).
- 1
0% lit
8.4 h
- 2
1% lit
8.5 h
- 3
5% lit
8.4 h
- 4
11% lit
8.0 h
- 5
20% lit
7.6 h
- 6
29% lit
7.2 h
- 7
40% lit
6.8 h
- 8
50% lit
6.3 h
- 9
60% lit
5.7 h
- 10
70% lit
5.0 h
- 11
78% lit
4.2 h
- 12
86% lit
3.3 h
- 13
92% lit
2.3 h
- 14
96% lit
1.3 h
- 15
99% lit
0.2 h
- 16
100% lit
0.0 h
- 17
99% lit
0.0 h
- 18
97% lit
0.0 h
- 19
92% lit
0.3 h
- 20
86% lit
0.7 h
- 21
79% lit
1.1 h
- 22
70% lit
1.5 h
- 23
60% lit
2.1 h
- 24
49% lit
2.8 h
- 25
38% lit
3.7 h
- 26
27% lit
4.8 h
- 27
17% lit
6.0 h
- 28
9% lit
7.4 h
- 29
3% lit
8.8 h
- 30
0% lit
9.7 h
- 31
0% lit
9.8 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 Augusts
Arlington Heights needs Kp 8 for the average oval edge to sit overhead. 3 of the 930 August days from 1996 to 2025 (0%) reached it in the GFZ Potsdam record, 7th of 12 months; storm days with Kp 5 or more made up 11%. Arlington Heights sits at 50.9 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 8.
August across United States
No month-page town in United States has more civil night on August 15 than Arlington Heights; the national median is 8.6 hours. Coming from July (7.9 hours at Arlington Heights), August adds darkness, and the nights keep growing into September (10.5 hours on the 15th).
| Town | Civil night | Cloud |
|---|---|---|
| Arlington Heights | 9.1 h | 67% |
| Buffalo | 9.0 h | 56% |
| Portland, Maine | 8.9 h | 52% |
| Minneapolis | 8.8 h | 49% |
| Duluth | 8.6 h | 52% |
| Fargo | 8.6 h | 49% |
| Seattle | 8.5 h | 48% |
| Juneau | 6.9 h | 79% |
| Anchorage | 6.3 h | 79% |
| Eagle River | 6.2 h | 79% |
| Fairbanks | 5.0 h | 75% |
Darkness and moon, every night
| Night | Civil | Astronomical | Moon-free dark | Moon-free, 10 PM to 2 AM | Moon lit |
|---|---|---|---|---|---|
| Sun Aug 1 | 8 h 26 min | 5 h 39 min | 8 h 26 min | 4 h | 0% |
| Mon Aug 2 | 8 h 28 min | 5 h 42 min | 8 h 28 min | 4 h | 1% |
| Tue Aug 3 | 8 h 31 min | 5 h 46 min | 8 h 22 min | 4 h | 5% |
| Wed Aug 4 | 8 h 33 min | 5 h 49 min | 7 h 58 min | 4 h | 11% |
| Thu Aug 5 | 8 h 36 min | 5 h 53 min | 7 h 35 min | 4 h | 20% |
| Fri Aug 6 | 8 h 38 min | 5 h 56 min | 7 h 12 min | 3 h 54 min | 29% |
| Sat Aug 7 | 8 h 41 min | 6 h | 6 h 46 min | 3 h 28 min | 40% |
| Sun Aug 8 | 8 h 44 min | 6 h 4 min | 6 h 17 min | 2 h 57 min | 50% |
| Mon Aug 9 | 8 h 46 min | 6 h 7 min | 5 h 42 min | 2 h 22 min | 60% |
| Tue Aug 10 | 8 h 49 min | 6 h 11 min | 5 h 1 min | 1 h 39 min | 70% |
| Wed Aug 11 | 8 h 51 min | 6 h 14 min | 4 h 12 min | 49 min | 78% |
| Thu Aug 12 | 8 h 54 min | 6 h 18 min | 3 h 17 min | 0 min | 86% |
| Fri Aug 13 | 8 h 57 min | 6 h 21 min | 2 h 18 min | 0 min | 92% |
| Sat Aug 14 | 8 h 59 min | 6 h 25 min | 1 h 16 min | 0 min | 96% |
| Sun Aug 15 | 9 h 2 min | 6 h 29 min | 14 min | 0 min | 99% |
| Mon Aug 16 | 9 h 5 min | 6 h 32 min | 0 min | 0 min | 100% |
| Tue Aug 17 | 9 h 7 min | 6 h 36 min | 0 min | 0 min | 99% |
| Wed Aug 18 | 9 h 10 min | 6 h 39 min | 0 min | 0 min | 97% |
| Thu Aug 19 | 9 h 13 min | 6 h 43 min | 18 min | 0 min | 92% |
| Fri Aug 20 | 9 h 16 min | 6 h 46 min | 40 min | 0 min | 86% |
| Sat Aug 21 | 9 h 19 min | 6 h 50 min | 1 h 4 min | 0 min | 79% |
| Sun Aug 22 | 9 h 21 min | 6 h 54 min | 1 h 32 min | 0 min | 70% |
| Mon Aug 23 | 9 h 24 min | 6 h 57 min | 2 h 5 min | 18 min | 60% |
| Tue Aug 24 | 9 h 27 min | 7 h 1 min | 2 h 47 min | 58 min | 49% |
| Wed Aug 25 | 9 h 30 min | 7 h 4 min | 3 h 40 min | 1 h 49 min | 38% |
| Thu Aug 26 | 9 h 33 min | 7 h 8 min | 4 h 45 min | 2 h 53 min | 27% |
| Fri Aug 27 | 9 h 35 min | 7 h 11 min | 6 h | 4 h | 17% |
| Sat Aug 28 | 9 h 38 min | 7 h 15 min | 7 h 22 min | 4 h | 9% |
| Sun Aug 29 | 9 h 41 min | 7 h 18 min | 8 h 45 min | 4 h | 3% |
| Mon Aug 30 | 9 h 44 min | 7 h 22 min | 9 h 44 min | 4 h | 0% |
| Tue Aug 31 | 9 h 47 min | 7 h 25 min | 9 h 47 min | 4 h | 0% |
Questions
- Can you see the northern lights in Arlington Heights in August?
- On dark, clear nights with enough activity. 31 of 31 nights at Arlington Heights have civil darkness, and 0% of past August days reached Kp 8.
- How dark is Arlington Heights in August?
- Arlington Heights averages 9.1 hours of civil night a night in August 2027, from 8 h 26 min on the 1st to 9 h 47 min on the last night.
- How cloudy is Arlington Heights in August?
- NASA POWER's 2001 to 2020 climatology gives Arlington Heights's 1 degree cell 67% mean cloud in August, against 74% for the whole year. It is an all-hours average, not a forecast.
- What is the best night in August 2027 for aurora in Arlington Heights?
- By darkness and moon alone, Aug 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Arlington Heights. Activity on that date will only be known hours ahead.
- Is August or September better in Arlington Heights?
- By civil night times the clear share, August scores 3.0 hours at Arlington Heights and September 4.3. 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.