Arizona Sky Village
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Arizona Sky Village clear sky chart from 2005-11-05 to 2017-08-12.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
59%
15255
34%
46487
23%
15212
71%
15212
42%
22674

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
57%
719
33%
2327
27%
716
67%
716
40%
1105
January16th to endNight
54%
768
36%
2496
27%
768
69%
768
38%
1210
February1st to 15thNight
55%
700
36%
2277
27%
696
71%
696
46%
977
February16th to endNight
50%
632
43%
1751
24%
632
68%
632
48%
846
March1st to 15thNight
49%
720
40%
1980
23%
720
65%
720
49%
952
March16th to endNight
55%
768
39%
2112
19%
768
71%
768
52%
978
April1st to 15thNight
46%
617
36%
1876
19%
617
65%
617
47%
850
April16th to endNight
49%
540
43%
1800
25%
540
75%
540
53%
683
May1st to 15thNight
47%
539
36%
1736
20%
539
65%
539
51%
701
May16th to endNight
51%
561
39%
1684
22%
561
68%
561
49%
737
June1st to 15thNight
65%
540
33%
1620
24%
540
72%
540
55%
686
June16th to endNight
67%
540
25%
1620
19%
540
72%
540
41%
814
July1st to 15thNight
70%
510
16%
1530
13%
510
71%
510
25%
970
July16th to endNight
65%
564
11%
1593
7%
531
72%
531
18%
1106
August1st to 15thNight
72%
527
19%
1600
19%
524
72%
524
26%
1012
August16th to endNight
71%
525
20%
1750
21%
525
73%
525
25%
1067
September1st to 15thNight
67%
557
23%
1712
22%
557
69%
557
27%
1072
September16th to endNight
70%
656
35%
1815
21%
656
80%
656
48%
933
October1st to 15thNight
68%
660
36%
1977
27%
660
75%
660
53%
917
October16th to endNight
76%
704
41%
2112
29%
704
85%
704
63%
886
November1st to 15thNight
61%
700
42%
2100
29%
700
73%
700
57%
882
November16th to endNight
53%
720
42%
2183
25%
720
70%
720
43%
1027
December1st to 15thNight
53%
720
38%
2340
27%
720
67%
720
41%
1064
December16th to endNight
50%
768
36%
2496
24%
768
66%
768
38%
1199

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
221332445%7%62%
47476
Night
221232345%7%65%
46694
TransparencyDay
20%5%7%14%26%25%
47171
Night
18%5%7%15%28%24%
46500
SeeingDay
6%17%20%28%21%6%
5119
Night
318%15%32%26%4
15263

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
121232345%6%64%
1611
16th to endDay
4333312347%61%
1728
February1st to 15thDay
2112223337%69%
1575
16th to endDay
121121335%6%68%
1721
March1st to 15thDay
332445%6%68%
1980
16th to endDay
112212246%73%
2112
April1st to 15thDay
11121225%6%74%
2072
16th to endDay
1111122382%
2160
May1st to 15thDay
11323335%74%
2211
16th to endDay
111113235%75%
2429
June1st to 15thDay
111213346%72%
2340
16th to endDay
22134245%6%7%59%
2340
July1st to 15thDay
5%2245%48%8%9%11%38%
2340
16th to endDay
6%426%7%48%9%9%12%27%
2467
August1st to 15thDay
5%426%8%48%8%9%11%31%
2265
16th to endDay
6%425%6%47%7%8%10%36%
2100
September1st to 15thDay
7%425%6%35%6%7%8%41%
1914
16th to endDay
4213423346%64%
1815
October1st to 15thDay
1113313246%70%
1653
16th to endDay
1222332476%
1760
November1st to 15thDay
11212235%76%
1759
16th to endDay
3212312235%71%
1776
December1st to 15thDay
2112314436%68%
1620
16th to endDay
1313313346%66%
1728
January1st to 15thNight
321321335%5%66%
2327
16th to endNight
321232335%5%64%
2496
February1st to 15thNight
111224336%72%
2277
16th to endNight
12114347%71%
1751
March1st to 15thNight
112222348%70%
1980
16th to endNight
111113235%76%
2112
April1st to 15thNight
1111213446%70%
1876
16th to endNight
1111225%82%
1800
May1st to 15thNight
11212235%77%
1736
16th to endNight
21221222477%
1684
June1st to 15thNight
2112111335%75%
1620
16th to endNight
11124245%6%7%60%
1620
July1st to 15thNight
22145%49%8%9%11%38%
1620
16th to endNight
3325%5%6%9%10%12%13%27%
1701
August1st to 15thNight
2325%6%36%7%9%12%39%
1609
16th to endNight
4415%5%45%6%8%11%41%
1750
September1st to 15thNight
6%4235%46%6%7%9%41%
1712
16th to endNight
422313345%67%
1815
October1st to 15thNight
1112213345%72%
1977
16th to endNight
111134479%
2112
November1st to 15thNight
111212335%77%
2100
16th to endNight
3212212235%73%
2183
December1st to 15thNight
22221235%6%69%
2340
16th to endNight
121231345%7%66%
2496

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
18%5%6%17%34%17%
1612
16th to endDay
23%4415%32%19%
1728
February1st to 15thDay
17%3414%31%29%
1575
16th to endDay
17%35%15%32%26%
1721
March1st to 15thDay
15%3411%35%29%
1980
16th to endDay
14%2410%35%32%
2112
April1st to 15thDay
11%2310%39%32%
2072
16th to endDay
9%128%27%50%
2160
May1st to 15thDay
12%248%28%43%
2211
16th to endDay
11%249%27%44%
2432
June1st to 15thDay
12%345%23%50%
2340
16th to endDay
20%5%6%10%22%35%
2340
July1st to 15thDay
32%11%16%16%13%9%
2201
16th to endDay
41%14%18%18%6%
2312
August1st to 15thDay
37%12%14%18%12%3
2250
16th to endDay
37%11%13%15%13%8%
2100
September1st to 15thDay
35%8%12%18%15%9%
1914
16th to endDay
20%35%16%33%19%
1815
October1st to 15thDay
15%27%16%27%29%
1653
16th to endDay
12%2417%32%30%
1760
November1st to 15thDay
10%3418%36%26%
1759
16th to endDay
18%3316%32%26%
1776
December1st to 15thDay
18%35%22%33%16%
1620
16th to endDay
21%39%21%31%12%
1728
January1st to 15thNight
19%46%16%32%19%
2327
16th to endNight
21%45%19%33%16%
2496
February1st to 15thNight
15%26%17%31%28%
2288
16th to endNight
14%4415%34%26%
1751
March1st to 15thNight
15%2413%33%30%
1980
16th to endNight
13%2410%39%29%
2112
April1st to 15thNight
14%2412%35%29%
1876
16th to endNight
9%129%31%45%
1800
May1st to 15thNight
10%348%30%43%
1737
16th to endNight
13%2312%29%38%
1685
June1st to 15thNight
11%25%6%24%50%
1620
16th to endNight
20%5%7%11%20%34%
1620
July1st to 15thNight
31%13%16%17%12%8%
1530
16th to endNight
38%17%23%15%4
1593
August1st to 15thNight
33%12%16%19%15%3
1600
16th to endNight
33%10%17%17%12%8%
1750
September1st to 15thNight
32%11%14%17%15%8%
1712
16th to endNight
19%45%16%37%16%
1815
October1st to 15thNight
15%38%17%26%29%
1977
16th to endNight
9%2416%29%36%
2112
November1st to 15thNight
10%2419%36%26%
2100
16th to endNight
17%3414%30%29%
2183
December1st to 15thNight
17%46%22%32%17%
2340
16th to endNight
19%48%22%32%12%
2496

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
7%11%31%38%11%
90
16th to endDay
9%11%18%38%16%5%
96
February1st to 15thDay
10%317%36%28%3
90
16th to endDay
10%33%26%18%11%
233
March1st to 15thDay
328%27%24%11%4
270
16th to endDay
6%30%27%21%10%3
288
April1st to 15thDay
5%30%28%24%8%2
269
16th to endDay
432%30%25%6%1
270
May1st to 15thDay
6%31%31%18%9%2
288
16th to endDay
422%33%29%9%1
330
June1st to 15thDay
5%13%25%33%15%6%
315
16th to endDay
5%10%11%36%30%5%
315
July1st to 15thDay
5%7%7%35%38%5%
305
16th to endDay
6%10%5%25%35%17%
327
August1st to 15thDay
7%6%6%26%35%18%
300
16th to endDay
6%5%6%27%42%10%
268
September1st to 15thDay
9%7%9%37%31%4
255
16th to endDay
9%10%16%30%27%6%
255
October1st to 15thDay
45%16%34%23%16%
93
16th to endDay
4316%27%38%10%
96
November1st to 15thDay
6%13%31%20%22%6%
90
16th to endDay
6%22%24%31%14%1
90
December1st to 15thDay
5%10%18%28%28%7%
90
16th to endDay
14%15%30%31%8%
96
January1st to 15thNight
418%15%38%19%3
720
16th to endNight
421%15%35%19%3
768
February1st to 15thNight
223%16%32%21%3
704
16th to endNight
223%23%37%12%
632
March1st to 15thNight
322%22%31%16%3
720
16th to endNight
222%17%34%20%2
768
April1st to 15thNight
224%25%36%11%
617
16th to endNight
124%23%31%16%2
540
May1st to 15thNight
123%26%32%15%1
540
16th to endNight
321%21%35%18%
563
June1st to 15thNight
317%11%42%22%1
540
16th to endNight
116%7%37%34%1
540
July1st to 15thNight
411%430%42%5%
510
16th to endNight
317%221%46%8%
564
August1st to 15thNight
310%216%53%12%
527
16th to endNight
6%9%419%50%9%
525
September1st to 15thNight
6%9%5%22%47%7%
557
16th to endNight
5%10%9%31%36%6%
656
October1st to 15thNight
210%15%36%29%5%
660
16th to endNight
210%9%35%35%7%
704
November1st to 15thNight
117%17%32%25%6%
700
16th to endNight
5%19%17%30%21%5%
720
December1st to 15thNight
5%21%17%30%21%4
720
16th to endNight
423%19%33%16%3
768
Page generated at 2017-08-13 11:16:26. Version ac04

Copyright 2017 A. Danko


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