Sonrisa Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sonrisa Observatory 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
74%
16110
31%
46601
28%
16067
76%
16067
45%
25213

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
30%
2315
30%
716
76%
716
41%
1209
January16th to endNight
66%
768
33%
2304
32%
768
70%
768
38%
1288
February1st to 15thNight
72%
698
33%
2106
35%
698
75%
698
44%
1119
February16th to endNight
62%
632
26%
1895
30%
632
63%
632
30%
1173
March1st to 15thNight
69%
720
28%
2160
31%
720
71%
720
40%
1198
March16th to endNight
73%
768
26%
2034
24%
768
74%
768
41%
1201
April1st to 15thNight
66%
719
25%
1799
18%
719
67%
719
41%
1104
April16th to endNight
71%
720
28%
1800
19%
720
72%
720
47%
1061
May1st to 15thNight
70%
589
26%
1669
19%
589
71%
589
39%
989
May16th to endNight
67%
561
23%
1685
19%
561
67%
561
37%
1005
June1st to 15thNight
70%
540
21%
1620
18%
540
70%
540
39%
951
June16th to endNight
86%
540
31%
1620
28%
540
86%
540
61%
745
July1st to 15thNight
85%
510
24%
1530
20%
510
85%
510
50%
786
July16th to endNight
80%
640
27%
1663
20%
601
79%
601
46%
913
August1st to 15thNight
82%
701
31%
1750
20%
697
82%
697
59%
926
August16th to endNight
87%
700
36%
1750
26%
700
87%
700
63%
902
September1st to 15thNight
85%
660
36%
1713
30%
660
85%
660
59%
872
September16th to endNight
85%
656
43%
1815
41%
656
86%
656
66%
831
October1st to 15thNight
79%
660
35%
1815
34%
660
80%
660
52%
953
October16th to endNight
74%
704
36%
2107
38%
704
75%
704
45%
1102
November1st to 15thNight
79%
700
33%
2275
38%
700
80%
700
50%
1068
November16th to endNight
78%
720
33%
2340
37%
720
80%
720
42%
1188
December1st to 15thNight
67%
720
32%
2340
35%
720
70%
720
38%
1255
December16th to endNight
64%
768
32%
2496
31%
768
68%
768
36%
1374

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
5%313213346%63%
47358
Night
6%5%23313347%56%
46809
TransparencyDay
22%25%17%26%25%
47060
Night
26%26%16%22%24%
46608
SeeingDay
6%5%22%41%19%4
5786
Night
8%25%31%40%12%
16123

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
8%423422345%59%
1620
16th to endDay
11%42321335%5%56%
1920
February1st to 15thDay
8%31331335%5%59%
1751
16th to endDay
11%6%24424447%47%
1579
March1st to 15thDay
6%423214449%57%
1800
16th to endDay
6%32332335%9%58%
2187
April1st to 15thDay
7%423314337%56%
2149
16th to endDay
5%311212246%66%
2160
May1st to 15thDay
5%5%23223445%60%
2280
16th to endDay
45%13222237%62%
2429
June1st to 15thDay
6%6%23212236%62%
2340
16th to endDay
212112235%76%
2340
July1st to 15thDay
2413213446%63%
2340
16th to endDay
231321346%8%63%
2389
August1st to 15thDay
1311112235%74%
2114
16th to endDay
112113346%73%
2100
September1st to 15thDay
11211235%5%72%
1917
16th to endDay
12121124475%
1815
October1st to 15thDay
5%424312346%62%
1815
16th to endDay
6%412112236%68%
1761
November1st to 15thDay
5%212223346%64%
1584
16th to endDay
6%413211347%61%
1620
December1st to 15thDay
8%41231445%9%53%
1620
16th to endDay
13%423313345%56%
1728
January1st to 15thNight
7%313324337%58%
2315
16th to endNight
11%414413235%56%
2304
February1st to 15thNight
8%313313245%59%
2101
16th to endNight
14%6%24424335%47%
1895
March1st to 15thNight
8%5%23223348%54%
2160
16th to endNight
7%6%2332345%8%51%
2034
April1st to 15thNight
10%7%24312347%51%
1799
16th to endNight
7%7%23312336%58%
1800
May1st to 15thNight
7%10%3432335%9%46%
1669
16th to endNight
9%10%2442235%7%47%
1684
June1st to 15thNight
6%12%4431346%8%44%
1620
16th to endNight
142321236%10%60%
1620
July1st to 15thNight
28%222236%6%11%51%
1620
16th to endNight
36%233245%6%10%51%
1777
August1st to 15thNight
36%2321246%11%55%
1760
16th to endNight
142121245%8%65%
1750
September1st to 15thNight
25%1221235%7%64%
1713
16th to endNight
23121125%6%72%
1815
October1st to 15thNight
4313322447%62%
1815
16th to endNight
7%413312345%61%
2107
November1st to 15thNight
4313212335%66%
2275
16th to endNight
5%313323347%60%
2340
December1st to 15thNight
9%424312347%54%
2340
16th to endNight
12%413312346%56%
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
28%2414%23%27%
1621
16th to endDay
30%36%14%15%29%
1920
February1st to 15thDay
27%35%14%22%26%
1751
16th to endDay
37%36%15%24%12%
1579
March1st to 15thDay
25%36%21%21%21%
1800
16th to endDay
25%49%25%20%14%
2187
April1st to 15thDay
29%37%24%24%10%
2149
16th to endDay
20%29%24%25%18%
2160
May1st to 15thDay
25%26%22%25%17%
2280
16th to endDay
22%26%25%32%10%
2432
June1st to 15thDay
24%1418%31%20%
2340
16th to endDay
12%28%29%47%
2340
July1st to 15thDay
20%2313%27%32%
2201
16th to endDay
18%310%24%29%14%
2240
August1st to 15thDay
14%1218%34%28%
2100
16th to endDay
12%2315%35%29%
2100
September1st to 15thDay
12%3312%34%34%
1917
16th to endDay
11%1311%36%35%
1815
October1st to 15thDay
23%3318%25%25%
1815
16th to endDay
20%2312%21%39%
1761
November1st to 15thDay
20%26%16%18%34%
1584
16th to endDay
23%35%15%19%34%
1620
December1st to 15thDay
28%39%15%17%26%
1620
16th to endDay
32%36%16%22%18%
1728
January1st to 15thNight
26%3413%20%30%
2315
16th to endNight
31%36%11%15%31%
2304
February1st to 15thNight
26%26%15%20%27%
2112
16th to endNight
39%3415%22%15%
1895
March1st to 15thNight
30%26%18%18%22%
2160
16th to endNight
30%49%19%21%15%
2034
April1st to 15thNight
32%37%24%20%11%
1799
16th to endNight
28%28%22%19%18%
1800
May1st to 15thNight
32%28%20%16%17%
1670
16th to endNight
34%28%24%17%11%
1685
June1st to 15thNight
33%27%18%23%14%
1620
16th to endNight
17%211%31%36%
1620
July1st to 15thNight
23%1414%28%27%
1530
16th to endNight
25%48%25%25%10%
1663
August1st to 15thNight
19%1322%33%18%
1750
16th to endNight
15%2414%33%29%
1750
September1st to 15thNight
17%2311%33%30%
1713
16th to endNight
14%1213%36%32%
1815
October1st to 15thNight
22%25%19%26%23%
1815
16th to endNight
25%2211%21%36%
2107
November1st to 15thNight
20%25%17%16%37%
2275
16th to endNight
25%35%16%16%32%
2340
December1st to 15thNight
30%37%14%18%25%
2340
16th to endNight
30%37%15%20%22%
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
25%6%13%40%15%
99
16th to endDay
13%8%30%37%7%2
288
February1st to 15thDay
8%6%33%34%15%
266
16th to endDay
14%11%32%31%8%
238
March1st to 15thDay
7%10%30%31%15%4
270
16th to endDay
411%27%39%11%5%
288
April1st to 15thDay
9%11%33%30%10%4
269
16th to endDay
414%35%33%8%3
270
May1st to 15thDay
12%7%28%37%10%2
288
16th to endDay
9%8%28%37%15%2
330
June1st to 15thDay
5%123%41%25%2
315
16th to endDay
213%49%27%7%
315
July1st to 15thDay
38%45%35%6%
305
16th to endDay
5%247%34%10%
327
August1st to 15thDay
29%55%27%6%
300
16th to endDay
17%53%30%7%
268
September1st to 15thDay
218%57%17%3
255
16th to endDay
4324%47%16%3
255
October1st to 15thDay
37%36%36%12%2
255
16th to endDay
10%224%39%18%4
219
November1st to 15thDay
25%14%34%35%7%
90
16th to endDay
5%7%23%40%21%2
90
December1st to 15thDay
4214%43%30%5%
90
16th to endDay
19%5%17%37%18%1
96
January1st to 15thNight
7%29%39%29%11%
720
16th to endNight
12%28%38%29%8%
768
February1st to 15thNight
9%27%38%32%10%
704
16th to endNight
16%27%41%26%6%
632
March1st to 15thNight
10%38%38%31%6%
720
16th to endNight
9%2437%37%8%
768
April1st to 15thNight
12%35%42%29%5%
719
16th to endNight
9%36%37%34%9%
720
May1st to 15thNight
9%25%36%37%7%
590
16th to endNight
10%47%31%42%4
563
June1st to 15thNight
5%25%41%40%4
540
16th to endNight
2129%58%7%
540
July1st to 15thNight
316%65%13%
510
16th to endNight
2111%61%22%
640
August1st to 15thNight
3115%60%18%
701
16th to endNight
19%58%28%
700
September1st to 15thNight
315%59%19%
660
16th to endNight
3328%48%15%
656
October1st to 15thNight
5%25%36%40%10%
660
16th to endNight
10%1429%36%18%
704
November1st to 15thNight
6%1435%38%14%
700
16th to endNight
7%15%34%33%17%
720
December1st to 15thNight
10%28%38%28%11%
720
16th to endNight
15%210%35%25%9%
768
Page generated at 2017-08-13 11:16:12. Version ac04

Copyright 2017 A. Danko


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