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Holladay

40.669° N   111.825° W  ·  1363 M
44 /100
PEAK
Marginal, but there is a 2 hours gap from 23:00.
BEST WINDOW 23:00–01:00 · ASTRO DARK 23:00–05:00 · MOON 1%
Transparency
0.89
Seeing
1.00
Cloud
42%
Moon
1%

Fair tonight

Hour by hour, local to Holladay. 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
0
0
31
43
41
33
33
28
24
44
5
0
BEST WINDOW
Low cloud
0%
0%
0%
0%
0%
0%
1%
0%
0%
1%
1%
2%
Mid cloud
12%
16%
11%
2%
4%
24%
23%
33%
46%
35%
7%
31%
High cloud
62%
79%
99%
96%
96%
94%
92%
96%
94%
25%
38%
34%
Transparency
0.97
0.89
0.83
0.80
0.79
0.81
0.77
0.77
0.72
0.65
0.65
0.63
Seeing
1.00
1.00
1.00
1.00
0.97
0.79
0.73
0.75
0.80
0.92
0.93
0.90
Moon clear
0%
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
−41
Transparency
−1
Seeing
−0
Moonlight
−0
Darkness
−58
Score
0
CLOUD 66% LOW 0% MID 12% HIGH 62% SUN 4.6° MOON 8.3° / 0% WIND 2 TEMP 26°
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
When a clear gap is worth driving for

Ask how long the gap is relative to your setup time and your exposure length. A two-hour gap is a real session for a visual observer and close to worthless for someone doing four-minute subs on a target that needs three hours.

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 22:30 · OBSERVE 23:00–01:00 · 2H · MEAN 38

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

202200020406
ASTRONOMICAL DARK FROM 23:00
SET UP 21:30 · OBSERVE 22:00–01:00 · 3H · MEAN 39

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

202200020406
SEEING DEGRADES AFTER 01:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 04:30 · OBSERVE 05:00–06:00 · 1H · MEAN 39

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

202200020406
HIGH CLOUD CLEARS 05:00TWILIGHT BEGINS 06:00
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

202200020406
CLOUD NEVER DROPS BELOW 42%
SET UP 04:30 · OBSERVE 05:00–06:00 · 1H · MEAN 38

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

202200020406
HIGH CLOUD CLEARS 05:00TWILIGHT BEGINS 06:00
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The next week of nights

Tonight · 12 Aug
44
Fair
MOON 0%
23:00–01:00
Tomorrow · 13 Aug
34
Poor
MOON 3%
Friday · 14 Aug
32
Poor
MOON 7%
Saturday · 15 Aug
86
Excellent
MOON 15%
00:00–01:00
Sunday · 16 Aug
58
Good
MOON 23%
00:00–01:00
Monday · 17 Aug
40
Fair
MOON 32%
00:00–01:00
Tuesday · 18 Aug
81
Excellent
MOON 42%
00:00–01:00
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Nearby locations

About this forecast

Conditions for Holladay, Utah, 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 →