Cielos Oscuros
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cielos Oscuros clear sky chart from 2005-11-05 to 2017-10-16.

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
73%
15882
38%
47046
32%
15846
79%
15846
57%
21505

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
72%
716
33%
2327
32%
716
78%
716
47%
1114
January16th to endNight
68%
768
37%
2419
35%
768
75%
768
46%
1191
February1st to 15thNight
69%
696
35%
2112
33%
696
76%
696
48%
1054
February16th to endNight
64%
632
36%
1895
36%
632
70%
632
46%
958
March1st to 15thNight
67%
720
34%
2133
30%
720
76%
720
53%
1010
March16th to endNight
67%
768
38%
2082
27%
768
75%
768
56%
1007
April1st to 15thNight
58%
719
36%
1799
17%
719
68%
719
54%
928
April16th to endNight
64%
669
42%
1749
21%
669
74%
669
64%
797
May1st to 15thNight
66%
539
37%
1619
25%
539
72%
539
62%
687
May16th to endNight
68%
561
37%
1685
26%
561
74%
561
61%
706
June1st to 15thNight
70%
540
33%
1620
26%
540
75%
540
69%
652
June16th to endNight
82%
408
40%
1488
43%
408
87%
408
79%
479
July1st to 15thNight
86%
412
33%
1432
33%
412
88%
412
59%
571
July16th to endNight
81%
564
35%
1593
30%
531
82%
531
53%
766
August1st to 15thNight
85%
634
39%
1707
27%
631
87%
631
73%
751
August16th to endNight
88%
764
43%
1910
29%
764
89%
764
72%
913
September1st to 15thNight
85%
720
39%
1890
30%
720
88%
720
67%
897
September16th to endNight
86%
716
49%
1980
43%
716
91%
716
80%
816
October1st to 15thNight
77%
720
42%
1980
35%
720
83%
720
67%
899
October16th to endNight
79%
708
44%
2175
42%
708
85%
708
63%
915
November1st to 15thNight
78%
700
38%
2275
39%
700
84%
700
60%
960
November16th to endNight
77%
720
41%
2340
42%
720
82%
720
58%
984
December1st to 15thNight
69%
720
34%
2340
33%
720
75%
720
43%
1157
December16th to endNight
62%
768
34%
2496
31%
768
70%
768
39%
1293

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
2112212235%73%
48363
Night
2212212335%72%
47237
TransparencyDay
14%2314%27%37%
48055
Night
15%2315%27%35%
47047
SeeingDay
411%29%36%14%3
5850
Night
35%13%35%33%8%
15897

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
322212337%69%
1611
16th to endDay
6%313222346%63%
1803
February1st to 15thDay
32122245%37%65%
1751
16th to endDay
5%313423345%61%
1579
March1st to 15thDay
22111235%6%70%
1827
16th to endDay
2212323349%66%
2139
April1st to 15thDay
2222213246%69%
2149
16th to endDay
1111212235%78%
2211
May1st to 15thDay
11212235%79%
2331
16th to endDay
112112235%76%
2429
June1st to 15thDay
111112482%
2340
16th to endDay
111387%
2465
July1st to 15thDay
2212212235%71%
2436
16th to endDay
2213224446%65%
2467
August1st to 15thDay
11112245%77%
2241
16th to endDay
111111235%78%
2292
September1st to 15thDay
111212135%78%
2068
16th to endDay
1112385%
1980
October1st to 15thDay
312212225%74%
1980
16th to endDay
112112226%77%
1712
November1st to 15thDay
1211111235%75%
1584
16th to endDay
3111212247%70%
1620
December1st to 15thDay
4315%31335%7%61%
1620
16th to endDay
7%313323346%62%
1728
January1st to 15thNight
3213323345%65%
2327
16th to endNight
5%313313345%64%
2419
February1st to 15thNight
3323222237%64%
2101
16th to endNight
5%214322445%63%
1895
March1st to 15thNight
1112213347%67%
2133
16th to endNight
211221335%7%69%
2082
April1st to 15thNight
222223336%71%
1799
16th to endNight
11211235%79%
1749
May1st to 15thNight
1112346%76%
1619
16th to endNight
11112335%78%
1684
June1st to 15thNight
1111225%81%
1620
16th to endNight
111289%
1488
July1st to 15thNight
2111212247%72%
1518
16th to endNight
1113323447%65%
1701
August1st to 15thNight
1111245%78%
1716
16th to endNight
1121233479%
1910
September1st to 15thNight
112212245%75%
1890
16th to endNight
1112387%
1980
October1st to 15thNight
111212335%76%
1980
16th to endNight
11111123478%
2175
November1st to 15thNight
1212212226%74%
2275
16th to endNight
222112245%74%
2340
December1st to 15thNight
4313423345%63%
2340
16th to endNight
7%323313336%60%
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
17%3426%34%12%
1612
16th to endDay
22%26%24%30%14%
1803
February1st to 15thDay
19%26%20%31%19%
1751
16th to endDay
25%35%17%30%17%
1579
March1st to 15thDay
14%36%19%33%22%
1827
16th to endDay
17%26%21%32%19%
2139
April1st to 15thDay
18%2317%32%25%
2149
16th to endDay
11%2217%30%34%
2211
May1st to 15thDay
9%2216%29%39%
2331
16th to endDay
12%1211%34%36%
2432
June1st to 15thDay
9%127%20%59%
2340
16th to endDay
6%1411%76%
2465
July1st to 15thDay
15%227%14%58%
2294
16th to endDay
18%2311%21%41%
2312
August1st to 15thDay
9%217%21%57%
2226
16th to endDay
10%218%23%53%
2292
September1st to 15thDay
11%128%22%52%
2068
16th to endDay
6%17%28%55%
1980
October1st to 15thDay
15%1110%29%41%
1980
16th to endDay
11%1313%31%38%
1712
November1st to 15thDay
12%2416%38%25%
1584
16th to endDay
15%26%18%32%24%
1620
December1st to 15thDay
23%47%22%29%12%
1620
16th to endDay
24%39%28%22%11%
1728
January1st to 15thNight
21%3418%35%16%
2327
16th to endNight
22%3423%24%22%
2419
February1st to 15thNight
22%26%19%26%22%
2112
16th to endNight
23%2418%32%18%
1895
March1st to 15thNight
16%35%17%32%24%
2133
16th to endNight
15%2422%31%22%
2082
April1st to 15thNight
16%2319%33%25%
1799
16th to endNight
10%2119%30%36%
1749
May1st to 15thNight
10%3215%29%38%
1620
16th to endNight
10%2311%32%38%
1685
June1st to 15thNight
8%118%19%59%
1620
16th to endNight
5%5%11%76%
1488
July1st to 15thNight
12%218%17%56%
1432
16th to endNight
18%3211%19%43%
1593
August1st to 15thNight
9%219%19%57%
1707
16th to endNight
10%226%22%55%
1910
September1st to 15thNight
12%2210%20%51%
1890
16th to endNight
6%17%24%59%
1980
October1st to 15thNight
11%2211%27%44%
1980
16th to endNight
11%2311%24%46%
2175
November1st to 15thNight
14%1215%36%28%
2275
16th to endNight
14%2417%30%32%
2340
December1st to 15thNight
23%36%18%31%15%
2340
16th to endNight
26%39%21%24%14%
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
12%13%32%33%8%
90
16th to endDay
9%11%23%32%18%4
171
February1st to 15thDay
413%26%35%18%2
266
16th to endDay
10%21%30%25%10%
238
March1st to 15thDay
6%17%30%26%17%2
270
16th to endDay
6%19%33%29%9%1
288
April1st to 15thDay
8%26%30%21%10%2
269
16th to endDay
5%29%34%21%7%1
270
May1st to 15thDay
116%38%31%9%3
288
16th to endDay
313%34%36%9%2
330
June1st to 15thDay
410%39%34%8%2
315
16th to endDay
6%30%40%16%5%
315
July1st to 15thDay
3327%43%17%5%
305
16th to endDay
3120%52%17%4
327
August1st to 15thDay
25%26%46%14%4
315
16th to endDay
1323%45%17%8%
332
September1st to 15thDay
1425%47%16%4
315
16th to endDay
28%22%43%20%2
315
October1st to 15thDay
39%34%34%14%2
315
16th to endDay
47%22%36%24%4
150
November1st to 15thDay
25%15%34%28%13%
90
16th to endDay
48%30%37%15%3
90
December1st to 15thDay
310%23%41%21%1
90
16th to endDay
10%8%20%36%19%4
96
January1st to 15thNight
6%312%37%28%11%
720
16th to endNight
7%413%38%27%8%
768
February1st to 15thNight
5%413%39%27%8%
704
16th to endNight
7%8%15%41%19%6%
632
March1st to 15thNight
37%17%42%22%8%
720
16th to endNight
210%16%36%28%5%
768
April1st to 15thNight
413%20%32%23%5%
719
16th to endNight
110%20%37%23%6%
669
May1st to 15thNight
27%21%35%28%4
540
16th to endNight
110%18%34%31%3
563
June1st to 15thNight
15%20%38%31%2
540
16th to endNight
213%35%42%4
408
July1st to 15thNight
36%34%48%6%
412
16th to endNight
217%29%53%4
564
August1st to 15thNight
18%33%49%5%
634
16th to endNight
25%24%50%16%
764
September1st to 15thNight
25%28%49%12%
720
16th to endNight
118%31%40%14%
716
October1st to 15thNight
2213%39%33%8%
720
16th to endNight
25%9%33%34%15%
708
November1st to 15thNight
2212%33%37%12%
700
16th to endNight
35%10%35%35%10%
720
December1st to 15thNight
5%6%11%39%28%9%
720
16th to endNight
8%8%14%37%24%6%
768
Page generated at 2017-10-17 13:35:28. Version ac04

Copyright 2017 A. Danko


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