Copernicus Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Copernicus Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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
69%
24471
38%
74399
29%
24430
79%
24430
59%
32651

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
62%
757
35%
2457
28%
756
74%
756
48%
1126
January11th to 20thNight
68%
736
39%
2391
32%
736
80%
736
54%
1053
January21st to endNight
60%
792
40%
2520
30%
792
76%
792
48%
1195
February1st to 10thNight
64%
720
38%
2160
28%
720
78%
720
53%
997
February11th to 20thNight
58%
700
40%
2099
30%
700
75%
700
52%
984
February21st to endNight
53%
592
38%
1776
29%
592
69%
592
51%
824
March1st to 10thNight
54%
720
35%
2160
25%
720
70%
720
53%
991
March11th to 20thNight
60%
720
36%
1994
26%
720
71%
720
54%
971
March21st to endNight
54%
792
37%
2178
19%
792
69%
792
55%
1036
April1st to 10thNight
55%
720
39%
1814
18%
720
67%
720
60%
894
April11th to 20thNight
51%
711
38%
1779
15%
711
64%
711
58%
883
April21st to endNight
60%
593
44%
1673
22%
593
73%
593
66%
719
May1st to 10thNight
60%
540
38%
1620
22%
540
70%
540
61%
690
May11th to 20thNight
66%
531
41%
1595
27%
531
75%
531
69%
644
May21st to endNight
66%
582
36%
1746
24%
582
74%
582
64%
721
June1st to 10thNight
73%
540
37%
1620
28%
540
79%
540
75%
627
June11th to 20thNight
70%
540
37%
1620
29%
540
77%
540
73%
633
June21st to endNight
79%
540
36%
1620
29%
540
84%
540
78%
621
July1st to 10thNight
90%
525
34%
1575
31%
525
91%
525
72%
646
July11th to 20thNight
89%
522
34%
1566
30%
522
89%
522
64%
676
July21st to endNight
88%
591
36%
1674
31%
558
88%
558
56%
789
August1st to 10thNight
82%
537
40%
1602
31%
534
83%
534
62%
708
August11th to 20thNight
89%
687
39%
1755
26%
687
91%
687
74%
816
August21st to endNight
89%
792
43%
1980
30%
792
90%
792
74%
930
September1st to 10thNight
84%
720
40%
1879
30%
720
87%
720
68%
889
September11th to 20thNight
84%
720
46%
1980
37%
720
90%
720
79%
823
September21st to endNight
82%
720
46%
1980
36%
720
90%
720
77%
822
October1st to 10thNight
70%
720
43%
1980
30%
720
82%
720
66%
892
October11th to 20thNight
75%
720
47%
2031
38%
720
83%
720
71%
869
October21st to endNight
70%
792
44%
2502
36%
792
83%
792
67%
969
November1st to 10thNight
74%
740
42%
2405
38%
740
85%
740
69%
919
November11th to 20thNight
76%
760
43%
2470
39%
760
86%
760
67%
949
November21st to endNight
68%
760
42%
2470
36%
760
80%
760
59%
1027
December1st to 10thNight
66%
760
36%
2470
32%
760
76%
760
51%
1131
December11th to 20thNight
66%
758
36%
2890
29%
758
78%
758
41%
1349
December21st to endNight
58%
821
24%
4368
28%
817
71%
817
30%
1838

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
2112223346%74%
74898
Night
2212223346%75%
74908
TransparencyDay
12%45%14%28%36%
74625
Night
13%35%15%28%36%
74703
SeeingDay
39%24%35%22%6%
14173
Night
36%19%36%30%7%
24497

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
3212213348%72%
1708
11th to 20thDay
3212322347%72%
1647
21st to endDay
321232345%6%69%
1834
February1st to 10thDay
221221345%7%72%
1800
11th to 20thDay
32222246%7%70%
1750
21st to endDay
3123222346%72%
1480
March1st to 10thDay
221331345%7%69%
1800
11th to 20thDay
231322345%8%67%
1964
21st to endDay
121231345%6%70%
2178
April1st to 10thDay
1212313348%72%
2142
11th to 20thDay
122223345%76%
2129
21st to endDay
2111212335%79%
2286
May1st to 10thDay
111213346%76%
2340
11th to 20thDay
111222336%78%
2301
21st to endDay
1211213446%77%
2530
June1st to 10thDay
1111112235%82%
2340
11th to 20thDay
1111223485%
2340
21st to endDay
11111223385%
2340
July1st to 10thDay
111222445%5%73%
2340
11th to 20thDay
11123235%6%6%69%
2340
21st to endDay
32244346%7%9%56%
2545
August1st to 10thDay
211232435%5%72%
2328
11th to 20thDay
2112213346%75%
2142
21st to endDay
211121335%6%75%
2376
September1st to 10thDay
2212222345%74%
2080
11th to 20thDay
1111123386%
1980
21st to endDay
1111212225%82%
1980
October1st to 10thDay
211232233477%
1980
11th to 20thDay
111111223482%
1927
21st to endDay
1112235%86%
1852
November1st to 10thDay
1111112245%81%
1674
11th to 20thDay
1112212245%79%
1710
21st to endDay
2112212337%75%
1710
December1st to 10thDay
2212313448%70%
1710
11th to 20thDay
32134345%6%10%59%
2169
21st to endDay
43123235%6%7%63%
3146
January1st to 10thNight
2313324448%67%
2457
11th to 20thNight
2212223447%71%
2391
21st to endNight
4212323448%67%
2520
February1st to 10thNight
1213323346%73%
2160
11th to 20thNight
3212223246%72%
2098
21st to endNight
3112323347%70%
1776
March1st to 10thNight
2213323348%69%
2160
11th to 20thNight
322232336%7%68%
1994
21st to endNight
1212313347%73%
2178
April1st to 10thNight
211221335%7%74%
1814
11th to 20thNight
1212213346%75%
1779
21st to endNight
1111213335%80%
1673
May1st to 10thNight
2111213336%77%
1620
11th to 20thNight
2111212236%80%
1594
21st to endNight
1112112335%79%
1746
June1st to 10thNight
1111225%85%
1620
11th to 20thNight
11111222484%
1620
21st to endNight
11111222485%
1620
July1st to 10thNight
111122235%479%
1620
11th to 20thNight
2112313346%74%
1620
21st to endNight
231233347%9%63%
1773
August1st to 10thNight
1112323345%73%
1611
11th to 20thNight
212111345%80%
1755
21st to endNight
2111213245%80%
1980
September1st to 10thNight
21221234477%
1879
11th to 20thNight
1111212386%
1980
21st to endNight
11111222485%
1980
October1st to 10thNight
2112212225%79%
1980
11th to 20thNight
211221123482%
2031
21st to endNight
111212235%83%
2502
November1st to 10thNight
1111112235%82%
2405
11th to 20thNight
112211236%81%
2470
21st to endNight
2112223235%78%
2470
December1st to 10thNight
3312223447%70%
2470
11th to 20thNight
221233446%9%64%
3041
21st to endNight
44133245%7%9%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
13%310%28%37%9%
1709
11th to 20thDay
15%5%7%28%33%13%
1647
21st to endDay
17%46%24%37%11%
1834
February1st to 10thDay
14%5%7%21%32%21%
1800
11th to 20thDay
13%45%19%35%24%
1760
21st to endDay
16%47%18%34%20%
1480
March1st to 10thDay
14%5%5%20%36%20%
1800
11th to 20thDay
17%45%19%35%20%
1964
21st to endDay
14%48%24%34%16%
2178
April1st to 10thDay
14%45%18%32%28%
2142
11th to 20thDay
12%4414%30%37%
2132
21st to endDay
10%3314%38%33%
2286
May1st to 10thDay
10%35%13%33%36%
2340
11th to 20thDay
9%3311%33%40%
2304
21st to endDay
10%3410%32%40%
2530
June1st to 10thDay
7%229%22%57%
2340
11th to 20thDay
6%225%18%67%
2340
21st to endDay
7%22313%73%
2340
July1st to 10thDay
13%436%13%61%
2276
11th to 20thDay
14%5%6%10%21%45%
2271
21st to endDay
21%5%8%14%19%32%
2404
August1st to 10thDay
14%448%17%53%
2313
11th to 20thDay
11%438%23%50%
2142
21st to endDay
11%349%20%53%
2376
September1st to 10thDay
13%347%16%56%
2080
11th to 20thDay
6%236%23%60%
1980
21st to endDay
9%226%27%54%
1980
October1st to 10thDay
13%3313%24%44%
1980
11th to 20thDay
8%239%32%45%
1927
21st to endDay
6%2310%38%41%
1852
November1st to 10thDay
8%2417%39%30%
1674
11th to 20thDay
9%45%16%39%26%
1710
21st to endDay
13%3321%36%25%
1710
December1st to 10thDay
15%5%9%22%31%19%
1710
11th to 20thDay
21%6%12%23%29%9%
2168
21st to endDay
21%5%12%28%23%11%
3146
January1st to 10thNight
17%48%25%33%12%
2457
11th to 20thNight
14%5%427%33%18%
2391
21st to endNight
19%46%23%32%16%
2520
February1st to 10thNight
15%47%18%34%22%
2160
11th to 20thNight
17%3419%28%29%
2099
21st to endNight
15%45%17%36%22%
1776
March1st to 10thNight
15%46%20%35%20%
2160
11th to 20thNight
15%45%16%34%25%
1994
21st to endNight
14%46%20%37%20%
2178
April1st to 10thNight
12%35%19%32%29%
1814
11th to 20thNight
12%4414%32%34%
1779
21st to endNight
9%3314%33%39%
1673
May1st to 10thNight
11%3411%32%40%
1620
11th to 20thNight
8%2313%30%44%
1595
21st to endNight
9%3311%30%45%
1746
June1st to 10thNight
5%228%22%60%
1620
11th to 20thNight
7%216%17%67%
1620
21st to endNight
6%21211%77%
1620
July1st to 10thNight
9%237%13%66%
1575
11th to 20thNight
13%25%10%21%49%
1566
21st to endNight
17%35%20%20%35%
1674
August1st to 10thNight
14%339%15%56%
1602
11th to 20thNight
8%349%20%55%
1755
21st to endNight
9%238%22%56%
1980
September1st to 10thNight
11%439%15%59%
1879
11th to 20thNight
7%236%22%61%
1980
21st to endNight
7%226%24%59%
1980
October1st to 10thNight
11%2211%24%49%
1980
11th to 20thNight
10%237%28%51%
2031
21st to endNight
8%3311%29%46%
2502
November1st to 10thNight
8%3317%38%32%
2405
11th to 20thNight
9%25%15%37%32%
2470
21st to endNight
13%2316%33%33%
2470
December1st to 10thNight
16%5%7%21%30%21%
2470
11th to 20thNight
19%6%9%20%32%14%
3041
21st to endNight
22%5%10%27%27%9%
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
9%11%25%39%13%3
270
11th to 20thDay
9%10%23%37%18%3
249
21st to endDay
412%24%33%22%5%
316
February1st to 10thDay
414%28%33%17%4
420
11th to 20thDay
7%16%29%34%12%2
415
21st to endDay
420%31%33%10%1
346
March1st to 10thDay
6%20%35%23%15%1
420
11th to 20thDay
5%14%34%31%15%2
420
21st to endDay
6%22%37%27%8%1
462
April1st to 10thDay
5%15%29%33%14%3
420
11th to 20thDay
5%21%36%27%11%1
412
21st to endDay
5%18%28%28%16%5%
420
May1st to 10thDay
315%33%30%14%5%
423
11th to 20thDay
311%28%35%16%6%
448
21st to endDay
49%26%36%19%7%
485
June1st to 10thDay
27%25%36%22%8%
450
11th to 20thDay
19%23%36%23%9%
450
21st to endDay
1422%42%23%8%
450
July1st to 10thDay
1214%44%26%11%
446
11th to 20thDay
1110%41%34%12%
444
21st to endDay
217%43%34%14%
487
August1st to 10thDay
4117%43%23%12%
447
11th to 20thDay
2212%39%33%12%
437
21st to endDay
3113%37%36%10%
495
September1st to 10thDay
1318%38%32%9%
450
11th to 20thDay
15%24%39%27%4
450
21st to endDay
35%22%36%29%6%
450
October1st to 10thDay
37%27%33%26%4
450
11th to 20thDay
27%19%34%33%5%
397
21st to endDay
110%22%33%27%7%
297
November1st to 10thDay
29%26%31%28%4
270
11th to 20thDay
36%19%41%21%9%
270
21st to endDay
28%27%26%28%9%
270
December1st to 10thDay
25%24%41%23%4
270
11th to 20thDay
19%24%36%24%6%
270
21st to endDay
6%11%31%32%16%3
297
January1st to 10thNight
39%21%33%26%8%
760
11th to 20thNight
35%21%40%24%6%
736
21st to endNight
6%6%24%38%21%6%
792
February1st to 10thNight
27%23%40%22%6%
720
11th to 20thNight
48%27%36%20%5%
704
21st to endNight
5%9%30%35%17%4
592
March1st to 10thNight
39%29%35%19%4
720
11th to 20thNight
38%24%34%22%8%
720
21st to endNight
214%28%34%18%4
792
April1st to 10thNight
310%29%33%20%5%
720
11th to 20thNight
214%30%30%19%5%
711
21st to endNight
19%27%36%22%6%
593
May1st to 10thNight
37%27%38%21%4
540
11th to 20thNight
26%23%34%30%5%
531
21st to endNight
28%21%34%29%5%
584
June1st to 10thNight
1420%41%29%4
540
11th to 20thNight
15%22%38%28%5%
540
21st to endNight
1217%41%34%6%
540
July1st to 10thNight
26%39%45%8%
525
11th to 20thNight
21441%47%5%
522
21st to endNight
22332%55%7%
591
August1st to 10thNight
218%43%41%5%
537
11th to 20thNight
25%31%52%10%
687
21st to endNight
25%31%46%15%
792
September1st to 10thNight
328%30%46%12%
720
11th to 20thNight
112%38%38%10%
720
21st to endNight
1212%37%36%13%
720
October1st to 10thNight
25%20%39%29%6%
720
11th to 20thNight
2317%38%30%10%
720
21st to endNight
27%18%28%33%12%
792
November1st to 10thNight
1418%35%32%9%
740
11th to 20thNight
2415%41%31%8%
760
21st to endNight
35%21%38%27%7%
760
December1st to 10thNight
5%322%37%27%5%
760
11th to 20thNight
5%423%38%27%4
760
21st to endNight
411%22%37%21%5%
836
Page generated at 2024-01-11 10:31:59. Version ac07

Copyright 2024 Attilla Danko


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