Observatorio Carl Sagan Cerro Azul
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatorio Carl Sagan Cerro Azul clear sky chart from 2005-11-06 to 2024-01-17.

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
68%
23978
34%
74337
28%
23929
75%
23929
46%
36981

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 10thNight
65%
757
33%
2457
30%
756
74%
756
45%
1206
January11th to 20thNight
65%
748
37%
2430
32%
748
76%
748
49%
1132
January21st to endNight
54%
792
36%
2574
28%
792
69%
792
39%
1315
February1st to 10thNight
62%
720
36%
2282
30%
720
74%
720
47%
1097
February11th to 20thNight
54%
700
32%
2099
24%
700
65%
700
42%
1101
February21st to endNight
55%
592
40%
1635
29%
592
68%
592
51%
836
March1st to 10thNight
53%
720
37%
1980
24%
720
66%
720
47%
1037
March11th to 20thNight
63%
720
37%
1980
26%
720
73%
720
52%
988
March21st to endNight
60%
792
38%
2178
24%
792
72%
792
54%
1084
April1st to 10thNight
66%
720
39%
1980
25%
720
76%
720
62%
917
April11th to 20thNight
57%
569
41%
1813
27%
569
75%
569
58%
748
April21st to endNight
61%
540
45%
1800
35%
540
77%
540
66%
686
May1st to 10thNight
66%
540
41%
1701
32%
540
77%
540
63%
690
May11th to 20thNight
74%
531
44%
1594
36%
531
80%
531
70%
646
May21st to endNight
73%
583
47%
1746
38%
582
80%
582
80%
651
June1st to 10thNight
75%
540
37%
1620
31%
540
78%
540
65%
700
June11th to 20thNight
76%
540
39%
1620
32%
540
79%
540
72%
660
June21st to endNight
74%
540
27%
1620
23%
540
75%
540
47%
818
July1st to 10thNight
74%
525
17%
1575
15%
525
75%
525
30%
971
July11th to 20thNight
71%
522
10%
1566
9%
522
71%
522
19%
1126
July21st to endNight
67%
591
8%
1674
6%
558
67%
558
17%
1240
August1st to 10thNight
74%
537
16%
1602
15%
534
74%
534
31%
995
August11th to 20thNight
70%
534
16%
1660
15%
534
71%
534
25%
1095
August21st to endNight
72%
627
20%
2013
20%
627
73%
627
26%
1281
September1st to 10thNight
68%
720
22%
1980
19%
720
69%
720
30%
1294
September11th to 20thNight
83%
720
37%
1980
32%
720
83%
720
54%
1025
September21st to endNight
82%
720
36%
1980
29%
720
83%
720
58%
975
October1st to 10thNight
81%
720
41%
2065
33%
720
86%
720
63%
946
October11th to 20thNight
77%
720
38%
2160
33%
720
81%
720
56%
1015
October21st to endNight
78%
792
44%
2376
37%
792
84%
792
68%
989
November1st to 10thNight
79%
740
44%
2220
37%
740
84%
740
64%
939
November11th to 20thNight
75%
760
42%
2280
36%
760
81%
760
57%
1045
November21st to endNight
60%
760
38%
2386
30%
760
71%
760
42%
1201
December1st to 10thNight
67%
760
36%
2470
35%
760
72%
760
45%
1203
December11th to 20thNight
62%
758
32%
2929
33%
758
70%
758
35%
1504
December21st to endNight
55%
828
23%
4312
30%
817
64%
817
29%
1825

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
43244345%5%6%60%
75001
Night
432442445%7%62%
74864
TransparencyDay
23%46%11%25%31%
74728
Night
22%46%12%26%30%
74659
SeeingDay
10%11%26%30%18%5%
13789
Night
6%415%37%32%6%
23996

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 10thDay
5%324433445%63%
1708
11th to 20thDay
4324434446%62%
1674
21st to endDay
6%425%223336%63%
1782
February1st to 10thDay
5%42432345%5%64%
1674
11th to 20thDay
6%5%25%424436%57%
1750
21st to endDay
5%5%23423336%64%
1619
March1st to 10thDay
5%425%3245%6%8%56%
1980
11th to 20thDay
6%422323346%66%
1980
21st to endDay
221432445%6%67%
2178
April1st to 10thDay
221322345%7%69%
1980
11th to 20thDay
221222222479%
2092
21st to endDay
1112212235%79%
2160
May1st to 10thDay
1212223335%78%
2255
11th to 20thDay
111232233477%
2301
21st to endDay
111111222385%
2530
June1st to 10thDay
3212313346%71%
2340
11th to 20thDay
221222334475%
2340
21st to endDay
4313425%5%7%6%60%
2340
July1st to 10thDay
6%437%8%48%7%8%8%36%
2340
11th to 20thDay
5%5%28%9%6%10%10%9%11%24%
2340
21st to endDay
12%6%37%8%8%9%8%8%8%22%
2545
August1st to 10thDay
8%5%36%6%5%8%8%8%10%33%
2328
11th to 20thDay
7%6%36%6%5%8%8%9%10%33%
2241
21st to endDay
5%5%37%7%5%8%7%9%8%35%
2338
September1st to 10thDay
9%6%36%6%46%8%6%7%39%
1980
11th to 20thDay
43145%45%5%5%7%57%
1980
21st to endDay
422232346%6%65%
1980
October1st to 10thDay
2212324346%71%
1892
11th to 20thDay
231232334473%
1800
21st to endDay
2212223345%73%
1980
November1st to 10thDay
1213323347%72%
1859
11th to 20thDay
441332245%5%69%
1900
21st to endDay
6%42332346%6%60%
1790
December1st to 10thDay
4325%5%345%46%60%
1710
11th to 20thDay
5%5%36%6%245%6%8%53%
2169
21st to endDay
442342345%7%62%
3146
January1st to 10thNight
4414435%45%6%61%
2457
11th to 20thNight
431332345%7%64%
2430
21st to endNight
7%5%24424336%60%
2574
February1st to 10thNight
4324423345%66%
2282
11th to 20thNight
5%5%34424446%59%
2098
21st to endNight
35%2333435%5%65%
1635
March1st to 10thNight
4425%3235%5%6%61%
1980
11th to 20thNight
431331334469%
1980
21st to endNight
2314333347%67%
2178
April1st to 10thNight
2212323347%71%
1980
11th to 20thNight
1213223335%76%
1813
21st to endNight
1212112235%79%
1800
May1st to 10thNight
111222333479%
1701
11th to 20thNight
111212346%79%
1594
21st to endNight
11111122487%
1746
June1st to 10thNight
2212223337%74%
1620
11th to 20thNight
2112213335%79%
1620
21st to endNight
22144346%6%6%61%
1620
July1st to 10thNight
4326%7%5%6%8%8%11%40%
1620
11th to 20thNight
5%6%37%8%5%9%10%11%13%24%
1620
21st to endNight
8%6%37%8%5%8%8%12%15%19%
1773
August1st to 10thNight
5%5%35%5%45%6%9%15%37%
1611
11th to 20thNight
6%5%37%6%47%7%8%12%34%
1660
21st to endNight
7%5%36%5%46%7%9%12%37%
2013
September1st to 10thNight
9%6%26%6%45%6%7%8%42%
1980
11th to 20thNight
5%31332345%8%63%
1980
21st to endNight
4213313345%71%
1980
October1st to 10thNight
1112322346%74%
2065
11th to 20thNight
342331223472%
2160
21st to endNight
1112212226%80%
2376
November1st to 10thNight
1212222345%76%
2220
11th to 20thNight
331332335%6%69%
2280
21st to endNight
6%42442445%6%60%
2386
December1st to 10thNight
6%41442445%7%59%
2470
11th to 20thNight
45%25%5%3445%6%57%
3041
21st to endNight
6%4244245%45%60%
4521

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 10thDay
24%2413%29%29%
1709
11th to 20thDay
23%25%10%28%31%
1674
21st to endDay
25%2213%28%31%
1782
February1st to 10thDay
22%2311%22%40%
1674
11th to 20thDay
29%2412%24%29%
1760
21st to endDay
23%227%27%40%
1619
March1st to 10thDay
24%249%26%34%
1980
11th to 20thDay
21%237%26%40%
1980
21st to endDay
18%247%34%35%
2178
April1st to 10thDay
16%228%33%40%
1980
11th to 20thDay
13%115%27%53%
2095
21st to endDay
10%126%29%52%
2160
May1st to 10thDay
12%125%23%57%
2255
11th to 20thDay
11%227%25%53%
2304
21st to endDay
7%12330%57%
2530
June1st to 10thDay
13%245%29%47%
2340
11th to 20thDay
12%345%24%54%
2340
21st to endDay
21%5%7%9%28%30%
2340
July1st to 10thDay
40%9%12%13%13%13%
2276
11th to 20thDay
44%16%19%15%42
2271
21st to endDay
51%15%16%12%5%1
2404
August1st to 10thDay
39%12%16%19%11%3
2313
11th to 20thDay
40%11%18%15%10%6%
2241
21st to endDay
38%12%14%16%12%8%
2338
September1st to 10thDay
41%8%9%14%19%10%
1980
11th to 20thDay
25%5%6%14%29%22%
1980
21st to endDay
19%47%16%35%19%
1980
October1st to 10thDay
15%37%16%30%29%
1892
11th to 20thDay
16%3310%31%37%
1800
21st to endDay
14%2411%26%43%
1980
November1st to 10thDay
14%2312%33%36%
1859
11th to 20thDay
18%2312%30%35%
1900
21st to endDay
24%2315%27%28%
1790
December1st to 10thDay
26%3414%28%25%
1710
11th to 20thDay
29%26%12%30%22%
2168
21st to endDay
21%349%40%24%
3146
January1st to 10thNight
24%25%11%30%28%
2457
11th to 20thNight
20%2413%26%33%
2430
21st to endNight
27%2411%29%26%
2574
February1st to 10thNight
22%139%25%38%
2282
11th to 20thNight
27%2413%26%28%
2099
21st to endNight
21%238%25%41%
1635
March1st to 10thNight
23%2412%26%33%
1980
11th to 20thNight
20%248%26%42%
1980
21st to endNight
19%248%33%33%
2178
April1st to 10thNight
15%139%38%35%
1980
11th to 20thNight
13%228%30%45%
1813
21st to endNight
10%137%31%48%
1800
May1st to 10thNight
11%228%27%50%
1701
11th to 20thNight
9%239%30%48%
1595
21st to endNight
5%115%36%52%
1746
June1st to 10thNight
13%226%34%43%
1620
11th to 20thNight
10%145%27%54%
1620
21st to endNight
19%7%7%11%22%34%
1620
July1st to 10thNight
33%11%16%15%13%13%
1575
11th to 20thNight
42%16%20%16%5%2
1566
21st to endNight
44%17%24%12%21
1674
August1st to 10thNight
32%11%19%22%11%5%
1602
11th to 20thNight
38%12%18%16%11%6%
1660
21st to endNight
34%12%16%17%13%8%
2013
September1st to 10thNight
36%9%13%17%16%9%
1980
11th to 20thNight
19%5%7%20%29%21%
1980
21st to endNight
17%47%18%34%20%
1980
October1st to 10thNight
12%46%16%32%29%
2065
11th to 20thNight
18%2412%29%36%
2160
21st to endNight
10%2412%32%41%
2376
November1st to 10thNight
12%2413%37%33%
2220
11th to 20thNight
17%2316%30%33%
2280
21st to endNight
25%3414%29%27%
2386
December1st to 10thNight
24%25%15%27%27%
2470
11th to 20thNight
28%35%14%27%23%
3041
21st to endNight
25%249%31%27%
4521

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 10thDay
14%12%27%34%11%2
270
11th to 20thDay
15%7%29%33%14%3
258
21st to endDay
13%11%33%30%11%2
264
February1st to 10thDay
12%10%28%32%15%4
294
11th to 20thDay
23%20%29%21%6%
415
21st to endDay
20%27%29%18%6%1
346
March1st to 10thDay
17%24%31%19%9%
420
11th to 20thDay
17%20%27%24%10%3
420
21st to endDay
14%27%32%17%8%2
462
April1st to 10thDay
7%21%36%21%10%3
420
11th to 20thDay
8%26%38%15%11%2
412
21st to endDay
9%19%39%19%10%4
420
May1st to 10thDay
11%17%38%23%8%3
423
11th to 20thDay
6%13%40%26%13%3
448
21st to endDay
6%15%46%24%7%2
485
June1st to 10thDay
6%8%43%29%11%4
450
11th to 20thDay
38%37%36%13%3
450
21st to endDay
4431%35%20%6%
450
July1st to 10thDay
8%215%40%25%9%
446
11th to 20thDay
9%19%36%34%12%
444
21st to endDay
13%110%32%32%12%
487
August1st to 10thDay
6%111%31%34%16%
447
11th to 20thDay
8%211%36%32%11%
437
21st to endDay
8%110%31%31%18%
495
September1st to 10thDay
12%313%39%25%7%
450
11th to 20thDay
6%217%40%27%8%
450
21st to endDay
7%7%20%38%22%6%
450
October1st to 10thDay
47%25%35%22%6%
362
11th to 20thDay
6%7%24%30%24%8%
270
21st to endDay
5%6%25%32%22%10%
297
November1st to 10thDay
7%12%22%38%18%3
270
11th to 20thDay
6%9%24%34%24%3
270
21st to endDay
13%17%27%29%13%1
270
December1st to 10thDay
11%10%26%34%18%1
270
11th to 20thDay
8%13%31%37%10%1
270
21st to endDay
21%15%23%27%13%2
297
January1st to 10thNight
7%318%44%24%5%
760
11th to 20thNight
6%421%41%23%4
748
21st to endNight
11%6%21%39%20%3
792
February1st to 10thNight
7%5%19%40%24%5%
720
11th to 20thNight
11%424%42%17%2
704
21st to endNight
8%8%24%43%15%2
592
March1st to 10thNight
7%8%26%40%17%3
720
11th to 20thNight
8%7%17%40%25%4
720
21st to endNight
5%8%23%41%21%3
792
April1st to 10thNight
35%21%47%23%2
720
11th to 20thNight
47%28%40%19%1
569
21st to endNight
35%28%42%20%1
540
May1st to 10thNight
27%22%47%20%2
540
11th to 20thNight
1418%46%28%3
531
21st to endNight
2420%44%29%1
584
June1st to 10thNight
4116%45%30%4
540
11th to 20thNight
2116%42%36%1
540
21st to endNight
3214%34%44%4
540
July1st to 10thNight
5%18%26%51%9%
525
11th to 20thNight
7%16%23%49%14%
522
21st to endNight
10%16%19%48%15%
591
August1st to 10thNight
7%16%16%54%17%
537
11th to 20thNight
7%17%16%51%18%
534
21st to endNight
7%15%17%51%18%
627
September1st to 10thNight
12%25%20%48%14%
720
11th to 20thNight
6%427%54%8%
720
21st to endNight
426%40%43%6%
720
October1st to 10thNight
2211%40%39%7%
720
11th to 20thNight
5%29%46%32%6%
720
21st to endNight
1411%38%38%8%
792
November1st to 10thNight
3410%40%37%6%
740
11th to 20thNight
5%312%39%36%4
760
21st to endNight
9%6%17%39%24%4
760
December1st to 10thNight
8%314%43%27%4
760
11th to 20thNight
8%419%47%21%2
760
21st to endNight
10%5%21%37%21%5%
836
Page generated at 2024-01-14 07:55:01. Version ac07

Copyright 2024 Attilla Danko


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