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Tsurugashima

35.960° N   139.403° E  ·  33 M
36 /100
PEAK
Marginal, but there is a 1 hour gap from 01:00.
BEST WINDOW 01:00–02:00 · ASTRO DARK 01:00–04:00 · MOON 0%
Transparency
0.20
Seeing
1.00
Cloud
45%
Moon
0%

Fair tonight

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

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
01
02
03
04
05
36
0
1
0
0
BEST WINDOW
Low cloud
38%
100%
98%
100%
100%
Mid cloud
3%
6%
16%
8%
24%
High cloud
11%
2%
4%
9%
81%
Transparency
0.10
0.10
0.20
0.10
0.10
Seeing
1.00
1.00
1.00
0.94
0.98
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
01 Fair · 36/100
Starting from
100
Cloud
−44
Transparency
−20
Seeing
−0
Moonlight
−0
Darkness
−0
Score
36
CLOUD 45% LOW 38% MID 3% HIGH 11% SUN -36.3° MOON -35.4° / 0% WIND 2 TEMP 22°
Excellent 75+ Good 55+ Fair 35+ Poor 15+ Not worth it Seeing is estimated from surface wind — see how we score.

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 36

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

010305
CLOUD RETURNS 02:00
SET UP 00:30 · OBSERVE 01:00–02:00 · 1H · MEAN 47

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

010305
CLOUD RETURNS 02:00MOONLIGHT IGNORED FOR THIS TARGET
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

010305
CLOUD NEVER DROPS BELOW 45%
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

010305
CLOUD NEVER DROPS BELOW 45%
SET UP 00:30 · OBSERVE 01:00–02:00 · 1H · MEAN 35

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

010305
CLOUD RETURNS 02:00
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The next week of nights

Tonight · 12 Aug
36
Fair
MOON 0%
01:00–02:00
Tomorrow · 13 Aug
5
Clouded out
MOON 1%
Friday · 14 Aug
16
Poor
MOON 5%
Saturday · 15 Aug
59
Good
MOON 8%
21:00–22:00
Sunday · 16 Aug
55
Good
MOON 19%
21:00–22:00
Monday · 17 Aug
26
Poor
MOON 28%
Tuesday · 18 Aug
44
Fair
MOON 37%
21:00–22:00
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Nearby locations

About this forecast

Conditions for Tsurugashima, Japan 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 →