Mean monthly frequency (%) of clear and overcast sky conditions (sunrise to sunset observations).
55° 03'N / 131° 34' W
108.9 ft. above sea level
midnight - midnight
sunrise - sunset
Analyses are based on hourly observations for the years 1971 - 1996.
Clear skies are defined as 0 to 0.30 coverage, partly cloudy 0.4 to 0.70, and cloudy skies 0.80 to 1.00.
Mean monthly frequency (%) of clear, partly cloudy, and cloudy sky conditions and mean cloudiness (fraction of sky coverage).
| Sky Condition |
Jan
|
Feb
|
Mar
|
Apr
|
May
|
Jun
|
Jul
|
Aug
|
Sep
|
Oct
|
Nov
|
Dec
|
| Clear |
16
|
18
|
16
|
15
|
18
|
15
|
17
|
18
|
18
|
11
|
11
|
11
|
| Partly Cloudy |
9
|
9
|
13
|
13
|
14
|
15
|
14
|
14
|
14
|
12
|
11
|
9
|
| Cloudy |
76
|
73
|
72
|
72
|
67
|
70
|
69
|
68
|
68
|
76
|
78
|
80
|
|
Mean Cloudiness
|
0.80
|
0.78
|
0.79
|
0.78
|
0.75
|
0.78
|
0.77
|
0.75
|
0.76
|
0.82
|
0.83
|
0.84
|