Can you see the northern lights in Sioux City in July?

On dark, clear nights with enough activity. 31 of 31 nights at Sioux City have civil darkness, and 0% of past July days reached Kp 8.

How dark is Sioux City in July?

Sioux City averages 7.9 hours of civil night a night in July 2027, from 7 h 30 min on the 1st to 8 h 21 min on the last night.

How cloudy is Sioux City in July?

NASA POWER's 2001 to 2020 climatology gives Sioux City's 1 degree cell 47% mean cloud in July, against 57% for the whole year. It is an all-hours average, not a forecast.

What is the best night in July 2027 for aurora in Sioux City?

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

Is July or August better in Sioux City?

By civil night times the clear share, July scores 4.1 hours at Sioux City and August 4.7. August comes out ahead.

Sioux City · July 2027

Northern lights in Sioux City in July 2027

Answer

July gives Sioux City 7.8 hours of civil night on the 15th, the 11th darkest of its 12 months, under 47% mean cloud. 0% of July days since 1996 reached Kp 8, enough for the oval edge to reach Sioux City.

7.9 h

civil night, average night

SunCalc for 42.50, -96.40; NASA POWER; GFZ Kp

July against the rest of the year

4.7

4.4

3.8

3.2

3.4

4.1

4.7

5.9

5.7

5.9

4.8

July cloud at Sioux City averages 47% in NASA POWER's 2001 to 2020 record, 10 points clearer than its yearly mean. September is Sioux City's clearest month at 44%. By civil night times clear sky, July scores 4.1 hours at Sioux City, 8th of 12. Minneapolis, 373 km away, averages 46%, clearer by 1 points.

Civil night at Sioux City starts July at 7 h 30 min and reaches 8 h 21 min by July 31 as the nights lengthen by 0.8 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 4.7 hours on the 15th.

July night by night

July opens toward a new moon on Jul 3, with full moon on Jul 18, in America/Chicago dates. Sioux City gets 117 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: Jul 1 (4 h), Jul 2 (4 h), Jul 3 (4 h).

1
6% lit
6.1 h
2
1% lit
7.3 h
3
0% lit
7.5 h
New
4
2% lit
7.3 h
5
6% lit
6.8 h
6
14% lit
6.3 h
7
23% lit
5.9 h
8
33% lit
5.5 h
9
44% lit
5.1 h
10
55% lit
4.7 h
11
65% lit
4.3 h
12
74% lit
3.8 h
13
83% lit
3.2 h
14
89% lit
2.5 h
15
95% lit
1.6 h
16
98% lit
0.7 h
17
100% lit
0.0 h
18
100% lit
0.0 h
Full
19
98% lit
0.1 h
20
94% lit
0.5 h
21
89% lit
0.9 h
22
82% lit
1.2 h
23
74% lit
1.6 h
24
65% lit
1.9 h
25
55% lit
2.3 h
26
45% lit
2.8 h
27
34% lit
3.4 h
28
24% lit
4.2 h
29
15% lit
5.2 h
30
7% lit
6.4 h
31
2% lit
7.8 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 Julys

Sioux City needs Kp 8 for the average oval edge to sit overhead. 3 of the 930 July 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 9%. Sioux City sits at 50.8 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.

July across United States

No month-page town in United States has more civil night on July 15 than Sioux City; the national median is 7.1 hours. Coming from June (7.4 hours at Sioux City), July adds darkness, and the nights keep growing into August (9.0 hours on the 15th).

Civil night on July 15 and July cloud, month-page towns in United States
Town	Civil night	Cloud
Sioux City	7.8 h	47%
Buffalo	7.8 h	56%
Portland, Maine	7.6 h	55%
Minneapolis	7.4 h	46%
Duluth	7.2 h	51%
Fargo	7.1 h	48%
Seattle	7.0 h	47%
Juneau	4.1 h	81%
Anchorage	2.1 h	83%
Eagle River	2.0 h	83%
Fairbanks	0.0 h	77%

Darkness and moon, every night

Sioux City, July 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
Thu Jul 1	7 h 30 min	4 h 8 min	6 h 8 min	4 h	6%
Fri Jul 2	7 h 31 min	4 h 10 min	7 h 15 min	4 h	1%
Sat Jul 3	7 h 31 min	4 h 11 min	7 h 31 min	4 h	0%
Sun Jul 4	7 h 32 min	4 h 13 min	7 h 21 min	4 h	2%
Mon Jul 5	7 h 33 min	4 h 15 min	6 h 46 min	3 h 29 min	6%
Tue Jul 6	7 h 35 min	4 h 17 min	6 h 17 min	2 h 59 min	14%
Wed Jul 7	7 h 36 min	4 h 19 min	5 h 52 min	2 h 34 min	23%
Thu Jul 8	7 h 37 min	4 h 21 min	5 h 30 min	2 h 10 min	33%
Fri Jul 9	7 h 38 min	4 h 23 min	5 h 8 min	1 h 47 min	44%
Sat Jul 10	7 h 40 min	4 h 26 min	4 h 44 min	1 h 23 min	55%
Sun Jul 11	7 h 41 min	4 h 28 min	4 h 18 min	56 min	65%
Mon Jul 12	7 h 43 min	4 h 31 min	3 h 48 min	25 min	74%
Tue Jul 13	7 h 44 min	4 h 33 min	3 h 12 min	0 min	83%
Wed Jul 14	7 h 46 min	4 h 36 min	2 h 28 min	0 min	89%
Thu Jul 15	7 h 48 min	4 h 39 min	1 h 37 min	0 min	95%
Fri Jul 16	7 h 49 min	4 h 42 min	39 min	0 min	98%
Sat Jul 17	7 h 51 min	4 h 45 min	0 min	0 min	100%
Sun Jul 18	7 h 53 min	4 h 48 min	0 min	0 min	100%
Mon Jul 19	7 h 55 min	4 h 51 min	9 min	0 min	98%
Tue Jul 20	7 h 57 min	4 h 54 min	32 min	6 min	94%
Wed Jul 21	7 h 59 min	4 h 57 min	53 min	26 min	89%
Thu Jul 22	8 h 1 min	5 h	1 h 13 min	45 min	82%
Fri Jul 23	8 h 3 min	5 h 3 min	1 h 34 min	1 h 4 min	74%
Sat Jul 24	8 h 5 min	5 h 7 min	1 h 55 min	1 h 25 min	65%
Sun Jul 25	8 h 7 min	5 h 10 min	2 h 20 min	1 h 49 min	55%
Mon Jul 26	8 h 9 min	5 h 13 min	2 h 49 min	2 h 17 min	45%
Tue Jul 27	8 h 12 min	5 h 17 min	3 h 25 min	2 h 52 min	34%
Wed Jul 28	8 h 14 min	5 h 20 min	4 h 12 min	3 h 38 min	24%
Thu Jul 29	8 h 16 min	5 h 24 min	5 h 12 min	4 h	15%
Fri Jul 30	8 h 19 min	5 h 27 min	6 h 25 min	4 h	7%
Sat Jul 31	8 h 21 min	5 h 31 min	7 h 46 min	4 h	2%

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

Questions

Can you see the northern lights in Sioux City in July?: On dark, clear nights with enough activity. 31 of 31 nights at Sioux City have civil darkness, and 0% of past July days reached Kp 8.
How dark is Sioux City in July?: Sioux City averages 7.9 hours of civil night a night in July 2027, from 7 h 30 min on the 1st to 8 h 21 min on the last night.
How cloudy is Sioux City in July?: NASA POWER's 2001 to 2020 climatology gives Sioux City's 1 degree cell 47% mean cloud in July, against 57% for the whole year. It is an all-hours average, not a forecast.
What is the best night in July 2027 for aurora in Sioux City?: By darkness and moon alone, Jul 1, with 4 h of moon-free darkness inside 10 PM to 2 AM at Sioux City. Activity on that date will only be known hours ahead.
Is July or August better in Sioux City?: By civil night times the clear share, July scores 4.1 hours at Sioux City and August 4.7. August 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.