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Juneau

58.302° N   134.420° W  ·  9 M
68 /100
PEAK
Worth setting up — 1 hour of workable sky from 01:00.
BEST WINDOW 01:00–02:00 · NO ASTRO DARK · MOON 1%
Transparency
0.46
Seeing
0.93
Cloud
2%
Moon
1%
At this latitude the sun never drops 18° below the horizon tonight, so astronomical darkness never arrives. Scores reflect the deepest twilight available.

Good tonight

Hour by hour, local to Juneau. Colour encodes the score and nothing else; every other measurement is luminance.

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
21
22
23
00
01
02
03
04
05
0
11
41
60
68
63
44
16
0
BEST WINDOW
Low cloud
2%
0%
0%
0%
0%
1%
2%
2%
2%
Mid cloud
1%
2%
2%
2%
2%
2%
1%
0%
0%
High cloud
0%
0%
0%
2%
1%
0%
0%
0%
1%
Transparency
0.27
0.33
0.40
0.43
0.45
0.46
0.46
0.46
0.44
Seeing
0.93
0.92
0.92
0.92
0.92
0.93
0.93
0.93
0.93
Moon clear
0%
down
down
down
down
down
down
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Inspect

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

Why this hour scored what it did
21 Clouded out · 0/100
Starting from
100
Cloud
−4
Transparency
−28
Seeing
−1
Moonlight
−0
Darkness
−67
Score
0
CLOUD 2% LOW 2% MID 1% HIGH 0% SUN -1.8° MOON 0.6° / 0% WIND 3 TEMP 16°
Excellent 75+ Good 55+ Fair 35+ Poor 15+ Not worth it Seeing is estimated from surface wind — see how we score.
Tonight's limiting factor
Civil, nautical and astronomical twilight

Astronomical darkness begins when the sun is 18° below the horizon. Above that, there is still measurable skyglow, and faint deep-sky work is compromised even though the sky looks black.

What are you doing tonight?

The same forecast, weighted for the target. Planetary work barely cares about moonlight; long exposures die on high cloud a visual observer would never notice.

SET UP 23:30 · OBSERVE 00:00–04:00 · 4H · MEAN 54

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

2123010305
TWILIGHT BEGINS 04:00
SET UP 21:30 · OBSERVE 22:00–05:00 · 7H · MEAN 72

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

2123010305
TWILIGHT BEGINS 05:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 22:30 · OBSERVE 23:00–04:00 · 5H · MEAN 50

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

2123010305
TWILIGHT BEGINS 04:00
SET UP 23:30 · OBSERVE 00:00–03:00 · 3H · MEAN 52

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

2123010305
TWILIGHT BEGINS 03:00
SET UP 22:30 · OBSERVE 23:00–04:00 · 5H · MEAN 53

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

2123010305
TWILIGHT BEGINS 04:00
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The next week of nights

Tonight · 12 Aug
68
Good
MOON 1%
01:00–02:00
Tomorrow · 13 Aug
78
Excellent
MOON 4%
01:00–03:00
Friday · 14 Aug
22
Poor
MOON 7%
Saturday · 15 Aug
11
Clouded out
MOON 17%
Sunday · 16 Aug
19
Poor
MOON 25%
Monday · 17 Aug
16
Poor
MOON 35%
Tuesday · 18 Aug
6
Clouded out
MOON 44%
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About this forecast

Conditions for Juneau, Alaska, 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 how dark the sky actually gets. Read the full method →