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Night Forecast

Weather
Observing Conditions.

Hour-by-hour night-window forecast built for observing, imaging, and planning around clouds, rain risk, visibility, dew spread, wind, humidity, and your active rig.

Fair conditions
Observing Outlook

Fair conditions expected

Night-window score reflects clouds, rain risk, visibility, dew risk, wind, and humidity. Clouds 60%, rain risk 29%, wind 8 mph.

64/100 Fair Best: 3 AM – 6 AM
Choose Forecast Date
Su M T W Th F Sa
16 17 18 19 20 21 22 23 24 25 26 27 28 29
Forecast Location Chicago Area 41.878100, -87.629800 41.87810, -87.62980
Overall 64 Fair
Clouds 60% Partly cloudy
Rain Risk 29% Max overnight
Visibility 9.1 mi Limited
Wind 8 mph Gusts 18 mph
Observatory Intelligence

No default rig selected

Add your telescope, focal length, and mount to unlock equipment-specific weather guidance.

Ephemeris can interpret wind, cloud layers, humidity, and dew risk differently for widefield, mid-focal, and long-focal-length setups.

Best Use Tonight General observing guidance
Avoid Tonight Rig-specific guidance unavailable
Improves After 3 AM
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Visual Observing

General sky conditions are available now.

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Deep Sky Imaging

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Why does rig data matter for imaging? →
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Planetary / Lunar

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Forecast Confidence

Low Confidence

Conditions appear changeable enough that the observing window may shift.

3 forecast source active
  • Forecast sources active: 2
  • Alert sources active: 1
  • Forecast models disagree during multiple observing hours
  • Cloud cover changes sharply during the night
Hour-by-Hour

Observing Window

2026-08-21 7 PM → next morning 6 AM
Time Score Outlook Clouds Low Mid High Rain Visibility Dew Spread Wind Humidity
8/21 - 7 PM 42 Poor 100% 57% 54% 100% 13% 9.3 mi 3.7°F ? 8 mph 88%
8/21 - 8 PM 58 Fair 93% 0% 72% 93% 16% 9.6 mi 3.7°F ? 4 mph 88%
8/21 - 9 PM 57 Fair 81% 0% 81% 73% 19% 9.8 mi 4.3°F ? 5 mph 86%
8/21 - 10 PM 65 Good 87% 0% 38% 87% 19% 10.1 mi 5°F ? 9 mph 84%
8/21 - 11 PM 69 Good 30% 0% 6% 30% 27% 10 mi 4.7°F ? 9 mph 85%
8/22 - 12 AM 38 Poor 91% 45% 88% 91% 29% 9.7 mi 4.3°F ? 10 mph 86%
8/22 - 1 AM 71 Good 99% 5% 0% 99% 17% 8.9 mi 3.3°F ? 7 mph 89%
8/22 - 2 AM 73 Good 100% 10% 0% 100% 10% 9.1 mi 3.3°F ? 6 mph 89%
8/22 - 3 AM 75 Good 1% 1% 0% 0% 6% 8.8 mi 3.3°F ? 9 mph 89%
8/22 - 4 AM 73 Good 9% 9% 0% 0% 4% 8.1 mi 2.4°F ? 10 mph 92%
8/22 - 5 AM 70 Good 17% 17% 0% 0% 1% 7.8 mi 2.1°F ? 9 mph 93%
8/22 - 6 AM 72 Good 12% 12% 0% 0% 1% 7.6 mi 1.8°F ? 6 mph 94%
Cloud Timeline

Cloud Cover by Hour

Each hour shows total cloud cover plus the split between low, mid, and high cloud layers.

Low Mid High
7 PM
100% Total
Low
57%
Mid
54%
High
100%
8 PM
93% Total
Low
0%
Mid
72%
High
93%
9 PM
81% Total
Low
0%
Mid
81%
High
73%
10 PM
87% Total
Low
0%
Mid
38%
High
87%
11 PM
30% Total
Low
0%
Mid
6%
High
30%
12 AM
91% Total
Low
45%
Mid
88%
High
91%
1 AM
99% Total
Low
5%
Mid
0%
High
99%
2 AM
100% Total
Low
10%
Mid
0%
High
100%
3 AM
1% Total
Low
1%
Mid
0%
High
0%
4 AM
9% Total
Low
9%
Mid
0%
High
0%
5 AM
17% Total
Low
17%
Mid
0%
High
0%
6 AM
12% Total
Low
12%
Mid
0%
High
0%
Why this score?

Limiting Factors

Dew Spread 3.5°F Major limiter
Humidity 89% Major limiter
Visibility 9.1 mi High impact
High Clouds 56% High impact
Mid Clouds 28% Moderate impact
Source Comparison

Forecast Sources

MVP starts with Open-Meteo; additional sources will improve confidence scoring.
Source Clouds Rain Humidity Wind Status
Open-Meteo 60% 29% 89% 8 mph Primary forecast
Tomorrow.io -- -- -- -- Secondary forecast active
National Weather Service -- -- -- -- Active alert cap: 15