HomeLocations › San Rafael

San Rafael

37.974° N   122.531° W  ·  13 M
4 /100
PEAK
Cloud will spoil it. Not a night for the telescope.
NO USABLE WINDOW · ASTRO DARK 22:00–05:00 · MOON 1%
Transparency
0.27
Seeing
0.73
Cloud
87%
Moon
1%

Clouded out tonight

Hour by hour, local to San Rafael. 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
4
4
1
0
0
0
0
0
0
0
Low cloud
63%
73%
90%
98%
100%
100%
100%
100%
100%
100%
100%
Mid cloud
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
High cloud
52%
52%
63%
59%
44%
45%
59%
69%
59%
0%
0%
Transparency
0.31
0.27
0.25
0.23
0.23
0.24
0.24
0.25
0.24
0.25
0.25
Seeing
0.70
0.73
0.71
0.69
0.67
0.69
0.70
0.70
0.68
0.66
0.65
Moon clear
0%
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
−74
Transparency
−7
Seeing
−1
Moonlight
−0
Darkness
−18
Score
0
CLOUD 81% LOW 63% MID 0% HIGH 52% SUN 0.6° MOON 4.8° / 0% WIND 5 TEMP 14°
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.

NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

202200020406
CLOUD NEVER DROPS BELOW 81%
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

202200020406
CLOUD NEVER DROPS BELOW 81%
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

202200020406
CLOUD NEVER DROPS BELOW 81%
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 81%
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

202200020406
CLOUD NEVER DROPS BELOW 81%
Advertisement
Reserved

The next week of nights

Tonight · 12 Aug
4
Clouded out
MOON 1%
Tomorrow · 13 Aug
1
Clouded out
MOON 3%
Friday · 14 Aug
0
Clouded out
MOON 7%
Saturday · 15 Aug
36
Fair
MOON 17%
23:00–00:00
Sunday · 16 Aug
21
Poor
MOON 25%
Monday · 17 Aug
49
Fair
MOON 35%
05:00–06:00
Tuesday · 18 Aug
17
Poor
MOON 44%
Advertisement
Reserved

Nearby locations

About this forecast

Conditions for San Rafael, California, 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 →