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Tonight · Sat, 10 October 2026

Tracy stargazing forecast tonight

Hourly clear-sky conditions for observing: cloud by layer, transparency, estimated seeing, moonlight and true astronomical darkness.

37.740°N 121.426°W ·17 m ·California, United States

NearbyStocktonLivermoreModestoSan RamonMore nearby
89
/100
Excellent conditions
at peak

A genuinely good night — 10 hours of clear, dark sky from 20:00.

Site darkness · peer measure
Bright skyNot multiplied into the conditions score
19.3–19.9 mag/arcsec²

The score describes tonight’s conditions. Site darkness helps you choose what to observe.

See target outlook ↓Planet observing times →
Best months at Tracy, California →Moonless nights →
Tonight in context · local sky & season

October historically: 20.5 qualifying nights/month on average (2005–2024). Regional cloud and darkness history, not tonight’s probability or a comparison with the conditions score.

A qualifying historical night has at least 3 hours of astronomical darkness and mean nighttime cloud ≤30%. This does not measure steady air or target visibility. Seasonal history →

Saturn: about 8.7h above 20° during this observing night’s darkness. Longest sampled dark-time opportunity among our four planet targets; not a weather ranking. Planet times →

Position calculations use roughly 20-minute samples. Clouds, skyglow and local obstructions still matter. Milky Way timing →

Best window
20:00 – 06:00
Window quality
83 / 100 avg
Astronomical dark
21:00 – 06:00
Moon
New moon, 1%
Transparency at peak
0.91
Seeing at peak (est.)
0.69
Visual limit (modelled)
4.5–6.0 mag
Tonight's limiting factor
Seeing

Seeing 0.69, estimated from surface wind. Expect to drop magnification. What this means →

The night, hour by hour

Colour = score · Luminance = everything else
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
83
87
87
89
88
84
81
81
79
72
48
Score
BEST WINDOW · 11 H
Low cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
3%
3%
Mid cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
High cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Transparency
0.97
0.97
0.96
0.94
0.91
0.84
0.69
0.58
0.62
0.53
0.34
0.25
0.42
Seeing
0.52
0.53
0.53
0.59
0.69
0.77
0.85
0.89
0.84
0.88
0.90
0.87
0.86
Moon clear
down
down
down
down
down
down
down
down
down
down
down
down
down
19
20
21
22
23
00
01
02
03
04
05
06
07
Inspect

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Score inspectorWhy this hour scored what it did Open peakClose
23 Excellent · 89/100
Starting from
100
Cloud
−0
Transparency
−3
Seeing
−7
Moonlight
−0
Darkness
−0
Score
89
CLOUD 0% LOW 0% MID 0% HIGH 0% SUN -49.9° MOON -51.0° / 1% WIND 5 TEMP 16°
Excellent 75+ Good 55+ Fair 35+ Poor 15+ Not worth it Seeing is estimated from surface wind — see how we score.

What can you actually do tonight?

This is GoodSeeing’s decision layer: the same forecast is weighted for your target and site darkness. Planetary work barely cares about moonlight; long exposures can fail on high cloud a visual observer would barely notice. Your choice is remembered on this device and becomes the default for new alert rules.

NO USABLE WINDOW FOR THIS TARGET TONIGHT

Darkness and moonlight dominate. Faint fuzzies need a genuinely dark sky more than they need steady air.

19212301030507
SITE GLOW LIMITS THIS TARGET
SET UP 19:30 · OBSERVE 20:00–07:00 · 11H · MEAN 82

Seeing is everything and moonlight is irrelevant. Bright targets punch through twilight, so darkness barely counts.

19212301030507
ASTRONOMICAL DARK FROM 20:00TWILIGHT BEGINS 07:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 44

Tolerates soft seeing, but high cloud wrecks a wide frame and moonlight raises the background everywhere.

19212301030507
ASTRONOMICAL DARK FROM 20:00TWILIGHT BEGINS 06:00SITE GLOW LIMITS FAINT TARGETS
SET UP 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 48

Needs conditions to hold still for hours. Sustained transparency matters more than any single good hour.

19212301030507
ASTRONOMICAL DARK FROM 20:00TWILIGHT BEGINS 06:00SITE GLOW LIMITS FAINT TARGETS
SET UP 19:30 · OBSERVE 20:00–02:00 · 6H · MEAN 37

Naked eye, whole sky. Total cloud and moonlight are the only things that count.

19212301030507
ASTRONOMICAL DARK FROM 20:00SITE GLOW LIMITS FAINT TARGETS

Deep-sky visual is your current default.

A darker option

Death Valley National Park

409 km away · Natural-dark sky · 21.8–21.9 mag/arcsec²

8conditions tonight
See the trade-off →

The next week of nights

Tonight · 10 Oct
89
Excellent
MOON 1%
20:00–06:00
Tomorrow · 11 Oct
85
Excellent
MOON 3%
20:00–06:00
Monday · 12 Oct
91
Excellent
MOON 7%
20:00–06:00
Tuesday · 13 Oct
100
Excellent
MOON 15%
05:00–06:00
Wednesday · 14 Oct
100
Excellent
MOON 22%
23:00–00:00
Thursday · 15 Oct
100
Excellent
MOON 31%
23:00–00:00
Friday · 16 Oct
92
Excellent
MOON 40%
23:00–00:00

Open a night for its forecast times. Later forecasts may have wider time steps; missing hours are not interpolated.

Tonight · 10 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
83
87
87
89
88
84
81
81
79
72
48
Score
Low cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
3%
3%
Mid cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
High cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Transparency
0.97
0.97
0.96
0.94
0.91
0.84
0.69
0.58
0.62
0.53
0.34
0.25
0.42
Seeing
0.52
0.53
0.53
0.59
0.69
0.77
0.85
0.89
0.84
0.88
0.90
0.87
0.86
Moon clear
down
down
down
down
down
down
down
down
down
down
down
down
down
19
20
21
22
23
00
01
02
03
04
05
06
07

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Tomorrow · 11 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
74
85
70
54
46
52
59
58
62
64
36
Score
Low cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
6%
12%
23%
24%
Mid cloud
7%
12%
3%
20%
40%
49%
38%
29%
27%
15%
1%
12%
7%
High cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Transparency
0.80
0.78
0.76
0.74
0.64
0.56
0.48
0.49
0.43
0.39
0.33
0.26
0.27
Seeing
0.73
0.75
0.86
0.84
0.96
0.98
1.00
1.00
0.99
1.00
1.00
1.00
1.00
Moon clear
3%
down
down
down
down
down
down
down
down
down
down
down
down
19
20
21
22
23
00
01
02
03
04
05
06
07

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Monday · 12 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
1
82
81
83
85
85
85
90
91
87
86
Score
Low cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Mid cloud
2%
1%
0%
0%
0%
0%
0%
1%
0%
0%
0%
0%
0%
High cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Transparency
1.00
1.00
0.72
0.70
0.71
0.79
0.79
0.79
0.84
0.80
0.69
0.70
1.00
Seeing
0.86
0.81
0.72
0.70
0.73
0.74
0.71
0.75
0.84
0.96
0.98
0.93
0.84
Moon clear
7%
7%
down
down
down
down
down
down
down
down
down
down
10%
18
19
20
21
22
23
00
01
02
03
04
05
11

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Tuesday · 13 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
95
100
Score
Low cloud
0%
0%
0%
0%
Mid cloud
0%
0%
0%
0%
High cloud
0%
0%
0%
5%
Transparency
1.00
1.00
1.00
1.00
Seeing
0.88
0.79
1.00
1.00
Moon clear
12%
down
down
down
17
23
05
11

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Wednesday · 14 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
100
100
Score
Low cloud
0%
0%
0%
0%
Mid cloud
0%
0%
0%
0%
High cloud
0%
0%
0%
0%
Transparency
1.00
1.00
1.00
1.00
Seeing
0.94
0.98
1.00
1.00
Moon clear
19%
down
down
down
17
23
05
11

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Thursday · 15 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
100
100
Score
Low cloud
0%
0%
0%
0%
Mid cloud
0%
0%
0%
0%
High cloud
0%
0%
0%
0%
Transparency
1.00
1.00
1.00
1.00
Seeing
1.00
1.00
1.00
1.00
Moon clear
27%
down
down
down
17
23
05
11

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Friday · 16 Oct · forecast times
Sky state
Shaded = daylight and twilight  ·  unshaded = astronomical dark
92
69
Score
Low cloud
0%
0%
3%
2%
Mid cloud
0%
0%
0%
0%
High cloud
0%
0%
0%
8%
Transparency
1.00
0.80
0.27
0.73
Seeing
0.99
1.00
1.00
1.00
Moon clear
35%
down
down
down
17
23
05
11

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Planning a trip?

Compare the next eight weekends → · Best months to visit → · Moonless nights →

More nearby locations 8 options · openclose

About this forecast

Exact-coordinate weather, sky geometry and site context.

Full method →20-year baseline →
Sources and scoring details openclose

Conditions for Tracy, California, United States are computed from the MET Norway forecast model for these exact coordinates, combined with sun and moon positions we calculate directly. The score weighs cloud cover by layer, atmospheric transparency, estimated seeing, moonlight and astronomical twilight. Site darkness is shown separately, then used only where artificial skyglow physically changes moon contrast, haze scattering, visual limits and target suitability.