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Decatur

34.606° N   86.983° W  ·  175 M
65 /100
PEAK
Worth setting up — 5 hours of workable sky from 00:00.
BEST WINDOW 00:00–05:00 · ASTRO DARK 22:00–05:00 · MOON 1%
Transparency
0.59
Seeing
0.97
Cloud
5%
Moon
1%

Good tonight

Hour by hour, local to Decatur. 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
0
61
60
28
41
45
44
59
65
37
0
BEST WINDOW
Low cloud
1%
0%
4%
7%
4%
2%
0%
0%
0%
1%
0%
Mid cloud
6%
5%
4%
42%
13%
15%
9%
8%
5%
2%
0%
High cloud
5%
8%
10%
27%
41%
34%
54%
9%
0%
23%
20%
Transparency
0.60
0.59
0.22
0.10
0.18
0.21
0.24
0.26
0.27
0.27
0.27
Seeing
0.87
0.91
0.97
0.55
0.69
0.84
0.86
0.82
0.82
0.88
0.91
Moon clear
down
down
down
down
down
down
down
down
down
down
down
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 Clouded out · 0/100
Starting from
100
Cloud
−8
Transparency
−15
Seeing
−3
Moonlight
−0
Darkness
−75
Score
0
CLOUD 10% LOW 1% MID 6% HIGH 5% SUN -4.8° MOON -0.4° / 0% WIND 3 TEMP 29°
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
Conditions for planets and the Moon

Seeing is everything. Darkness and moonlight barely matter, and a hazy, humid night that ruins deep-sky work is often the steadiest night of the year for planetary detail.

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 00:00–05:00 · 5H · MEAN 51

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

202200020406
CLOUD RETURNS 05:00
SET UP 23:30 · OBSERVE 00:00–06:00 · 6H · MEAN 59

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

202200020406
TWILIGHT BEGINS 06:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 23:30 · OBSERVE 00:00–05:00 · 5H · MEAN 46

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

202200020406
CLOUD RETURNS 05:00
SET UP 02:30 · OBSERVE 03:00–05:00 · 2H · MEAN 49

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

202200020406
HIGH CLOUD CLEARS 03:00CLOUD RETURNS 05:00
SET UP 23:30 · OBSERVE 00:00–05:00 · 5H · MEAN 53

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

202200020406
CLOUD RETURNS 05:00
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The next week of nights

Tonight · 12 Aug
65
Good
MOON 0%
00:00–05:00
Tomorrow · 13 Aug
83
Excellent
MOON 3%
22:00–05:00
Friday · 14 Aug
82
Excellent
MOON 7%
21:00–02:00
Saturday · 15 Aug
93
Excellent
MOON 15%
01:00–02:00
Sunday · 16 Aug
95
Excellent
MOON 23%
01:00–02:00
Monday · 17 Aug
70
Good
MOON 32%
01:00–02:00
Tuesday · 18 Aug
80
Excellent
MOON 42%
01:00–02:00
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Nearby locations

About this forecast

Conditions for Decatur, Alabama, 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 →