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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 65%, rain risk 32%, wind 6 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 65% Partly cloudy
Rain Risk 32% Max overnight
Visibility 10.3 mi Fair
Wind 6 mph Gusts 13 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 4 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 68 Good 85% 0% 85% 79% 23% 19.6 mi 14.8°F ? 5 mph 60%
8/21 - 8 PM 53 Fair 99% 52% 86% 99% 15% 15 mi 9.9°F ? 3 mph 71%
8/21 - 9 PM 48 Fair 100% 46% 100% 100% 22% 13.7 mi 8.7°F ? 6 mph 74%
8/21 - 10 PM 61 Fair 97% 0% 72% 97% 19% 10.3 mi 6.1°F ? 11 mph 81%
8/21 - 11 PM 44 Poor 84% 84% 48% 77% 24% 10.5 mi 5.3°F ? 10 mph 83%
8/22 - 12 AM 61 Fair 82% 4% 10% 82% 32% 8.4 mi 2.7°F ? 4 mph 91%
8/22 - 1 AM 69 Good 95% 5% 0% 95% 19% 7.8 mi 2.1°F ? 6 mph 93%
8/22 - 2 AM 65 Good 100% 18% 0% 100% 11% 7.8 mi 2.4°F ? 3 mph 92%
8/22 - 3 AM 72 Good 14% 14% 0% 0% 4% 7.7 mi 1.8°F ? 5 mph 94%
8/22 - 4 AM 77 Good 4% 4% 0% 0% 4% 7.7 mi 1.8°F ? 5 mph 94%
8/22 - 5 AM 72 Good 13% 13% 0% 0% 1% 7.7 mi 1.7°F ? 5 mph 94%
8/22 - 6 AM 77 Good 5% 5% 0% 0% 4% 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
85% Total
Low
0%
Mid
85%
High
79%
8 PM
99% Total
Low
52%
Mid
86%
High
99%
9 PM
100% Total
Low
46%
Mid
100%
High
100%
10 PM
97% Total
Low
0%
Mid
72%
High
97%
11 PM
84% Total
Low
84%
Mid
48%
High
77%
12 AM
82% Total
Low
4%
Mid
10%
High
82%
1 AM
95% Total
Low
5%
Mid
0%
High
95%
2 AM
100% Total
Low
18%
Mid
0%
High
100%
3 AM
14% Total
Low
14%
Mid
0%
High
0%
4 AM
4% Total
Low
4%
Mid
0%
High
0%
5 AM
13% Total
Low
13%
Mid
0%
High
0%
6 AM
5% Total
Low
5%
Mid
0%
High
0%
Why this score?

Limiting Factors

Humidity 85% Major limiter
Dew Spread 4.9°F Major limiter
High Clouds 61% High impact
Visibility 10.3 mi High impact
Mid Clouds 33% 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 65% 32% 85% 6 mph Primary forecast
Tomorrow.io -- -- -- -- Secondary forecast active
National Weather Service -- -- -- -- Active alert cap: 20