Mean monthly frequency (%) of clear and overcast sky conditions (midnight to midnight observations).
59° 39'N / 151° 29' W
89 ft. above sea level
midnight - midnight
sunrise - sunset
Analyses are based on hourly observations for the years 1971 - 1997.
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 conditions and mean cloudiness (fraction of sky coverage).
| Sky Condition |
Jan
|
Feb
|
Mar
|
Apr
|
May
|
Jun
|
Jul
|
Aug
|
Sep
|
Oct
|
Nov
|
Dec
|
| Clear |
26
|
31
|
31
|
24
|
20
|
18
|
18
|
21
|
20
|
24
|
28
|
20
|
| Partly Cloudy |
12
|
11
|
12
|
15
|
16
|
17
|
17
|
16
|
15
|
15
|
14
|
12
|
| Cloudy |
62
|
58
|
57
|
61
|
64
|
65
|
65
|
63
|
65
|
61
|
58
|
68
|
|
Mean Cloudiness
|
0.69
|
0.64
|
0.64
|
0.69
|
0.72
|
0.74
|
0.74
|
0.72
|
0.73
|
0.69
|
0.66
|
0.75
|