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Alvalade

38.753° N   9.144° W  ·  91 M
45 /100
PEAK
Marginal, but there is a 3 hours gap from 23:00.
BEST WINDOW 23:00–02:00 · ASTRO DARK 23:00–06:00 · MOON 0%
Transparency
0.38
Seeing
0.74
Cloud
6%
Moon
0%

Fair tonight

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

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
21
22
23
00
01
02
03
04
05
06
07
0
51
45
41
39
27
19
20
34
9
0
BEST WINDOW
Low cloud
1%
6%
32%
38%
40%
56%
70%
66%
48%
53%
70%
Mid cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
High cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Transparency
0.41
0.38
0.32
0.30
0.28
0.25
0.26
0.25
0.26
0.25
0.24
Seeing
0.61
0.64
0.61
0.66
0.66
0.68
0.68
0.72
0.74
0.74
0.74
Moon clear
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
21 Clouded out · 0/100
Starting from
100
Cloud
−1
Transparency
−24
Seeing
−7
Moonlight
−0
Darkness
−68
Score
0
CLOUD 1% LOW 1% MID 0% HIGH 0% SUN -5.2° MOON -2.4° / 0% WIND 6 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 21:30 · OBSERVE 22:00–02:00 · 4H · MEAN 45

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

212301030507
CLOUD RETURNS 02:00
SET UP 21:30 · OBSERVE 22:00–02:00 · 4H · MEAN 50

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

212301030507
CLOUD RETURNS 02:00MOONLIGHT IGNORED FOR THIS TARGET
SET UP 21:30 · OBSERVE 22:00–02:00 · 4H · MEAN 44

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

212301030507
CLOUD RETURNS 02:00
SET UP 21:30 · OBSERVE 22:00–23:00 · 1H · MEAN 41

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

212301030507
CLOUD RETURNS 23:00
SET UP 21:30 · OBSERVE 22:00–02:00 · 4H · MEAN 47

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

212301030507
CLOUD RETURNS 02:00
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The next week of nights

Tonight · 12 Aug
45
Fair
MOON 0%
23:00–02:00
Tomorrow · 13 Aug
51
Fair
MOON 2%
23:00–01:00
Friday · 14 Aug
54
Fair
MOON 6%
01:00–04:00
Saturday · 15 Aug
66
Good
MOON 13%
01:00–02:00
Sunday · 16 Aug
81
Excellent
MOON 21%
01:00–02:00
Monday · 17 Aug
83
Excellent
MOON 30%
01:00–02:00
Tuesday · 18 Aug
77
Excellent
MOON 39%
01:00–02:00
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Nearby locations

About this forecast

Conditions for Alvalade, Portugal 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 →