GoodSeeing
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Zanzibar

-6.164° S   39.198° E  ·  14 M
64 /100
PEAK
Worth setting up — 10 hours of workable sky from 20:00.
BEST WINDOW 20:00–06:00 · ASTRO DARK 20:00–06:00 · MOON 0%
Transparency
0.43
Seeing
0.59
Cloud
0%
Moon
0%

Good tonight

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

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
20
21
22
23
00
01
02
03
04
05
06
07
64
63
64
62
64
62
60
58
57
48
7
0
BEST WINDOW
Low cloud
0%
0%
0%
0%
0%
2%
4%
7%
10%
16%
31%
31%
Mid cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
15%
10%
High cloud
6%
4%
0%
2%
2%
1%
1%
1%
1%
0%
0%
0%
Transparency
0.43
0.39
0.40
0.37
0.41
0.36
0.34
0.35
0.36
0.10
0.10
0.31
Seeing
0.42
0.41
0.37
0.37
0.37
0.41
0.43
0.41
0.45
0.53
0.59
0.63
Moon clear
down
down
down
down
down
down
down
down
down
down
down
0%
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
20 Good · 64/100
Starting from
100
Cloud
−3
Transparency
−22
Seeing
−11
Moonlight
−0
Darkness
−0
Score
64
CLOUD 6% LOW 0% MID 0% HIGH 6% SUN -23.6° MOON -22.4° / 0% WIND 8 TEMP 25°
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
What the GoodSeeing score actually measures

One number from 0 to 100 per hour, combining cloud, transparency, seeing, moonlight and darkness. Cloud gates everything else — no amount of steady, dark air rescues an overcast sky.

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 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 66

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

202200020406
CLOUD RETURNS 06:00
SET UP 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 60

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

202200020406
CLOUD RETURNS 06:00SEEING STAYS SOFT THROUGHOUTMOONLIGHT IGNORED FOR THIS TARGET
SET UP 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 64

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

202200020406
CLOUD RETURNS 06:00
SET UP 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 53

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

202200020406
CLOUD RETURNS 06:00
SET UP 19:30 · OBSERVE 20:00–06:00 · 10H · MEAN 74

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

202200020406
CLOUD RETURNS 06:00
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The next week of nights

Tonight · 12 Aug
64
Good
MOON 0%
20:00–06:00
Tomorrow · 13 Aug
69
Good
MOON 2%
20:00–06:00
Friday · 14 Aug
63
Good
MOON 6%
20:00–03:00
Saturday · 15 Aug
63
Good
MOON 13%
21:00–22:00
Sunday · 16 Aug
55
Good
MOON 21%
21:00–22:00
Monday · 17 Aug
50
Fair
MOON 30%
21:00–22:00
Tuesday · 18 Aug
59
Good
MOON 39%
21:00–22:00
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Nearby locations

About this forecast

Conditions for Zanzibar, Tanzania 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 →