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Hwasun

35.061° N   126.987° E  ·  75 M
58 /100
PEAK
Worth setting up — 3 hours of workable sky from 02:00.
BEST WINDOW 02:00–05:00 · ASTRO DARK 02:00–05:00 · MOON 0%
Transparency
0.43
Seeing
1.00
Cloud
45%
Moon
0%

Good tonight

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

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
02
03
04
05
06
58
47
47
14
0
BEST WINDOW
Low cloud
0%
0%
0%
0%
0%
Mid cloud
1%
1%
1%
0%
0%
High cloud
45%
69%
68%
84%
84%
Transparency
0.43
0.42
0.40
0.38
0.36
Seeing
1.00
1.00
1.00
1.00
1.00
Moon clear
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
02 Good · 58/100
Starting from
100
Cloud
−25
Transparency
−17
Seeing
−0
Moonlight
−0
Darkness
−0
Score
58
CLOUD 45% LOW 0% MID 1% HIGH 45% SUN -36.3° MOON -35.8° / 0% WIND 1 TEMP 23°
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 01:30 · OBSERVE 02:00–05:00 · 3H · MEAN 48

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

020406
CLOUD RETURNS 05:00
SET UP 01:30 · OBSERVE 02:00–06:00 · 4H · MEAN 52

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

020406
TWILIGHT BEGINS 06:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 01:30 · OBSERVE 02:00–05:00 · 3H · MEAN 40

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

020406
CLOUD RETURNS 05:00
SET UP 01:30 · OBSERVE 02:00–03:00 · 1H · MEAN 37

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

020406
CLOUD RETURNS 03:00
SET UP 01:30 · OBSERVE 02:00–05:00 · 3H · MEAN 45

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

020406
CLOUD RETURNS 05:00
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The next week of nights

Tonight · 12 Aug
58
Good
MOON 0%
02:00–05:00
Tomorrow · 13 Aug
51
Fair
MOON 1%
02:00–05:00
Friday · 14 Aug
37
Fair
MOON 5%
04:00–05:00
Saturday · 15 Aug
6
Clouded out
MOON 8%
Sunday · 16 Aug
26
Poor
MOON 19%
Monday · 17 Aug
68
Good
MOON 28%
21:00–22:00
Tuesday · 18 Aug
32
Poor
MOON 37%
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Nearby locations

About this forecast

Conditions for Hwasun, South Korea 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 →