Mean monthly frequency (%) of clear and overcast sky conditions (midnight to midnight observations).
55° 13'N / 162° 44' W
78.1 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 0.40 to 0.70, and cloudy skies 0.80 to 1.00.
Mean monthly frequency (%) of clear, partly cloudy, and cloudy sky condition and mean cloudiness (fraction of sky coverage).
| Sky Condition |
Jan
|
Feb
|
Mar
|
Apr
|
May
|
Jun
|
Jul
|
Aug
|
Sep
|
Oct
|
Nov
|
Dec
|
| Clear |
12
|
11
|
13
|
6
|
5
|
4
|
3
|
2
|
5
|
6
|
9
|
9
|
| Partly Cloudy |
11
|
12
|
12
|
10
|
10
|
6
|
5
|
6
|
10
|
16
|
14
|
14
|
| Cloudy |
75
|
77
|
75
|
84
|
85
|
90
|
92
|
92
|
85
|
78
|
75
|
76
|
|
Mean Cloudiness
|
0.82
|
0.83
|
0.81
|
0.89
|
0.89
|
0.92
|
0.94
|
0.94
|
0.89
|
0.85
|
0.83
|
0.84
|