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Lancaster

40.038° N   76.305° W  ·  116 M
64 /100
PEAK
Worth setting up — 6 hours of workable sky from 23:00.
BEST WINDOW 23:00–05:00 · ASTRO DARK 22:00–05:00 · MOON 0%
Transparency
0.24
Seeing
0.92
Cloud
7%
Moon
0%

Good tonight

Hour by hour, local to Lancaster. 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
6
20
57
42
63
55
54
64
20
0
BEST WINDOW
Low cloud
5%
9%
21%
1%
4%
5%
6%
11%
3%
52%
56%
Mid cloud
24%
48%
51%
13%
9%
0%
13%
11%
0%
0%
2%
High cloud
98%
77%
38%
2%
52%
3%
2%
2%
4%
8%
1%
Transparency
0.14
0.13
0.10
0.21
0.24
0.24
0.23
0.23
0.24
0.23
0.24
Seeing
1.00
0.86
0.76
0.83
0.86
0.87
0.88
0.92
0.91
0.90
0.86
Moon clear
0%
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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
20 Clouded out · 0/100
Starting from
100
Cloud
−66
Transparency
−12
Seeing
−0
Moonlight
−0
Darkness
−22
Score
0
CLOUD 98% LOW 5% MID 24% HIGH 98% SUN 0.4° MOON 3.8° / 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.

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 23:00–05:00 · 6H · MEAN 56

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

202200020406
HIGH CLOUD CLEARS 23:00CLOUD RETURNS 05:00
SET UP 22:30 · OBSERVE 23:00–05:00 · 6H · MEAN 67

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

202200020406
HIGH CLOUD CLEARS 23:00CLOUD RETURNS 05:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 00:30 · OBSERVE 01:00–05:00 · 4H · MEAN 56

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

202200020406
HIGH CLOUD CLEARS 01:00CLOUD RETURNS 05:00
SET UP 00:30 · OBSERVE 01:00–05:00 · 4H · MEAN 45

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

202200020406
HIGH CLOUD CLEARS 01:00CLOUD RETURNS 05:00
SET UP 22:30 · OBSERVE 23:00–05:00 · 6H · MEAN 59

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

202200020406
HIGH CLOUD CLEARS 23:00CLOUD RETURNS 05:00
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The next week of nights

Tonight · 12 Aug
64
Good
MOON 0%
23:00–05:00
Tomorrow · 13 Aug
63
Good
MOON 3%
03:00–05:00
Friday · 14 Aug
41
Fair
MOON 7%
22:00–23:00
Saturday · 15 Aug
59
Good
MOON 15%
02:00–03:00
Sunday · 16 Aug
30
Poor
MOON 23%
Monday · 17 Aug
52
Fair
MOON 32%
02:00–03:00
Tuesday · 18 Aug
83
Excellent
MOON 42%
02:00–03:00
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Nearby locations

About this forecast

Conditions for Lancaster, Pennsylvania, 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 →