Mean monthly frequency (%) of clear and overcast sky conditions (midnight to midnight observations).
57° 45'N / 152° 29' W
19.0 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 |
23
|
29
|
29
|
20
|
17
|
15
|
16
|
20
|
22
|
29
|
32
|
25
|
| Partly Cloudy |
14
|
11
|
12
|
13
|
12
|
11
|
12
|
15
|
17
|
17
|
15
|
14
|
| Cloudy |
63
|
59
|
58
|
67
|
71
|
74
|
72
|
65
|
61
|
54
|
53
|
61
|
|
Mean Cloudiness
|
0.72
|
0.67
|
0.66
|
0.75
|
0.78
|
0.80
|
0.79
|
0.73
|
0.72
|
0.64
|
0.63
|
0.70
|