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Saint Croix

17.727° N   64.747° W  ·  42 M
43 /100
PEAK
Marginal, but there is a 1 hour gap from 01:00.
BEST WINDOW 01:00–02:00 · ASTRO DARK 21:00–05:00 · MOON 0%
Transparency
0.43
Seeing
0.30
Cloud
27%
Moon
0%

Fair tonight

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

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
19
20
21
22
23
00
01
02
03
04
05
06
0
25
27
34
26
26
43
27
29
36
30
0
BEST WINDOW
Low cloud
30%
45%
34%
20%
31%
7%
2%
24%
21%
19%
17%
31%
Mid cloud
1%
2%
12%
5%
3%
6%
2%
15%
13%
9%
8%
0%
High cloud
46%
43%
51%
49%
68%
93%
51%
36%
37%
9%
15%
14%
Transparency
0.41
0.43
0.43
0.40
0.42
0.39
0.39
0.10
0.10
0.10
0.39
0.40
Seeing
0.40
0.30
0.21
0.23
0.25
0.25
0.26
0.19
0.23
0.18
0.16
0.15
Moon clear
0%
down
down
down
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
19 Clouded out · 0/100
Starting from
100
Cloud
−48
Transparency
−12
Seeing
−6
Moonlight
−0
Darkness
−34
Score
0
CLOUD 63% LOW 30% MID 1% HIGH 46% SUN -3.7° MOON 0.6° / 0% WIND 8 TEMP 28°
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
Why thin high cloud ruins long exposures

Cirrus you can barely see will halo your bright stars, lift your background and vary between frames. Visual observers shrug it off. Long exposures integrate it, so it accumulates.

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 00:30 · OBSERVE 01:00–02:00 · 1H · MEAN 46

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

192123010305
HIGH CLOUD CLEARS 01:00
SET UP 00:30 · OBSERVE 01:00–02:00 · 1H · MEAN 39

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

192123010305
HIGH CLOUD CLEARS 01:00SEEING STAYS SOFT THROUGHOUTMOONLIGHT IGNORED FOR THIS TARGET
SET UP 00:30 · OBSERVE 01:00–02:00 · 1H · MEAN 41

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

192123010305
HIGH CLOUD CLEARS 01:00
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

192123010305
CONDITIONS STAY BELOW THE USABLE THRESHOLD
SET UP 00:30 · OBSERVE 01:00–02:00 · 1H · MEAN 49

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

192123010305
HIGH CLOUD CLEARS 01:00
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The next week of nights

Tonight · 12 Aug
43
Fair
MOON 0%
01:00–02:00
Tomorrow · 13 Aug
39
Fair
MOON 3%
04:00–05:00
Friday · 14 Aug
47
Fair
MOON 7%
20:00–01:00
Saturday · 15 Aug
43
Fair
MOON 15%
20:00–21:00
Sunday · 16 Aug
21
Poor
MOON 23%
Monday · 17 Aug
45
Fair
MOON 32%
20:00–21:00
Tuesday · 18 Aug
59
Good
MOON 42%
02:00–03:00
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Nearby locations

About this forecast

Conditions for Saint Croix, U.S. Virgin Islands 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 →