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Kopernik Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kopernik Observatory clear sky chart from 2005-11-06 to 2024-01-16.

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
28%
22991
14%
74767
8%
22946
35%
22946
16%
53300

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
13%
760
10%
2649
4%
757
21%
757
8%
2022
January11th to 20thNight
17%
741
9%
2578
5%
741
24%
741
9%
2010
January21st to endNight
13%
792
11%
2574
4%
792
22%
792
9%
2002
February1st to 10thNight
12%
720
10%
2340
3%
720
20%
720
10%
1806
February11th to 20thNight
10%
703
9%
2221
3%
700
20%
700
9%
1726
February21st to endNight
14%
592
14%
1776
6%
592
25%
592
12%
1335
March1st to 10thNight
17%
720
13%
2121
7%
720
26%
720
13%
1583
March11th to 20thNight
16%
720
15%
1980
6%
720
25%
720
14%
1482
March21st to endNight
19%
792
17%
2080
5%
792
28%
792
16%
1540
April1st to 10thNight
17%
720
13%
1800
3%
720
23%
720
16%
1379
April11th to 20thNight
22%
711
15%
1775
5%
711
27%
711
21%
1288
April21st to endNight
24%
720
15%
1800
4%
720
30%
720
20%
1307
May1st to 10thNight
30%
446
16%
1526
10%
446
37%
446
15%
1084
May11th to 20thNight
30%
354
19%
1416
13%
354
44%
354
16%
913
May21st to endNight
41%
388
16%
1551
15%
388
49%
388
19%
959
June1st to 10thNight
44%
360
16%
1440
17%
360
53%
360
19%
889
June11th to 20thNight
42%
360
14%
1440
14%
360
50%
360
19%
891
June21st to endNight
48%
360
15%
1440
17%
360
54%
360
23%
845
July1st to 10thNight
56%
350
14%
1400
17%
350
62%
350
23%
831
July11th to 20thNight
58%
348
18%
1392
23%
348
61%
348
25%
791
July21st to endNight
53%
402
16%
1494
17%
380
57%
380
22%
915
August1st to 10thNight
56%
537
16%
1600
12%
534
59%
534
30%
1011
August11th to 20thNight
54%
601
14%
1665
9%
601
57%
601
23%
1166
August21st to endNight
54%
792
19%
1980
10%
792
56%
792
31%
1320
September1st to 10thNight
45%
720
17%
1800
8%
720
48%
720
29%
1229
September11th to 20thNight
51%
720
26%
1800
17%
720
56%
720
36%
1151
September21st to endNight
41%
720
21%
2030
16%
720
47%
720
26%
1373
October1st to 10thNight
36%
720
15%
2160
12%
720
42%
720
20%
1504
October11th to 20thNight
29%
720
16%
2160
8%
720
38%
720
20%
1473
October21st to endNight
20%
792
13%
2438
7%
792
29%
792
14%
1831
November1st to 10thNight
28%
740
18%
2407
11%
740
38%
740
19%
1597
November11th to 20thNight
20%
760
16%
2536
9%
760
30%
760
14%
1787
November21st to endNight
21%
760
13%
2660
7%
760
31%
760
13%
1910
December1st to 10thNight
16%
760
9%
2660
5%
760
21%
760
8%
2085
December11th to 20thNight
16%
760
9%
3235
4%
759
21%
759
7%
2448
December21st to endNight
13%
830
5%
4843
3%
817
20%
817
4%
3817

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
16%10%47%6%45%5%5%7%31%
74753
Night
16%10%48%6%35%5%5%7%32%
75033
TransparencyDay
53%6%11%19%10%1
74459
Night
52%6%12%19%10%1
74861
SeeingDay
25%17%28%18%9%3
13633
Night
23%15%28%24%9%1
22998

By Month

Percentage Cloud Cover NE (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
12%13%8%12%8%45%5%5%6%23%
1517
11th to 20thDay
15%15%6%14%8%46%5%5%5%17%
1489
21st to endDay
10%13%8%14%10%46%5%45%22%
1782
February1st to 10thDay
17%13%7%12%10%45%5%45%19%
1620
11th to 20thDay
13%14%7%10%8%46%45%6%22%
1627
21st to endDay
18%13%412%9%3445%5%23%
1480
March1st to 10thDay
14%12%7%11%7%3445%5%27%
1833
11th to 20thDay
17%13%7%8%7%34445%29%
1980
21st to endDay
19%13%5%8%6%3445%5%28%
2275
April1st to 10thDay
16%12%5%6%5%35%45%6%32%
2160
11th to 20thDay
16%10%47%5%445%5%6%34%
2134
21st to endDay
19%12%46%6%34347%33%
2160
May1st to 10thDay
20%10%36%5%45%46%6%31%
2445
11th to 20thDay
19%7%36%5%45%46%7%33%
2478
21st to endDay
15%6%26%6%35%5%6%9%38%
2725
June1st to 10thDay
18%6%35%6%45%6%6%9%32%
2520
11th to 20thDay
16%6%36%5%46%6%5%9%34%
2520
21st to endDay
13%7%35%6%45%5%7%9%36%
2520
July1st to 10thDay
11%5%36%7%5%6%6%7%10%36%
2520
11th to 20thDay
10%5%36%6%35%6%7%10%39%
2520
21st to endDay
12%6%36%6%47%6%7%9%35%
2733
August1st to 10thDay
11%6%35%6%46%7%6%9%36%
2327
11th to 20thDay
15%7%36%6%46%6%6%9%33%
2217
21st to endDay
14%7%36%7%46%6%7%7%34%
2376
September1st to 10thDay
17%7%36%435%5%5%8%37%
2160
11th to 20thDay
15%6%25%5%35%45%7%43%
2160
21st to endDay
18%7%35%5%35%5%6%6%37%
1926
October1st to 10thDay
16%9%47%6%4445%8%34%
1800
11th to 20thDay
17%10%47%6%45%45%7%33%
1800
21st to endDay
23%13%36%6%44446%26%
1917
November1st to 10thDay
14%11%27%6%34347%38%
1671
11th to 20thDay
16%14%5%8%6%3445%5%31%
1643
21st to endDay
18%15%5%7%7%35%45%7%24%
1520
December1st to 10thDay
18%16%7%8%7%46%45%5%19%
1520
11th to 20thDay
21%14%9%10%5%23336%25%
1906
21st to endDay
22%21%7%9%7%3443415%
2772
January1st to 10thNight
13%13%6%12%8%46%5%5%6%21%
2649
11th to 20thNight
16%13%5%11%8%46%46%7%21%
2578
21st to endNight
11%11%6%12%12%6%6%5%6%5%21%
2574
February1st to 10thNight
16%11%6%11%8%46%5%5%6%23%
2340
11th to 20thNight
14%13%6%11%9%46%5%45%22%
2219
21st to endNight
19%11%411%7%35%45%6%26%
1776
March1st to 10thNight
14%11%8%10%6%45%45%5%28%
2111
11th to 20thNight
16%11%5%8%6%44445%31%
1979
21st to endNight
17%13%47%5%345%5%6%32%
2080
April1st to 10thNight
18%11%5%7%6%25%447%30%
1800
11th to 20thNight
19%10%46%5%2445%6%35%
1775
21st to endNight
19%8%36%5%45%446%37%
1800
May1st to 10thNight
21%11%36%6%245%45%34%
1526
11th to 20thNight
13%7%36%5%35%7%7%8%35%
1415
21st to endNight
13%6%36%4445%6%8%42%
1550
June1st to 10thNight
17%6%35%5%2346%9%40%
1440
11th to 20thNight
15%6%25%445%45%9%40%
1440
21st to endNight
11%5%345%45%6%5%8%45%
1440
July1st to 10thNight
8%5%45%5%45%46%10%44%
1440
11th to 20thNight
11%424435%6%7%9%45%
1440
21st to endNight
13%6%35%5%36%5%6%9%40%
1582
August1st to 10thNight
8%6%25%7%346%6%9%45%
1611
11th to 20thNight
13%6%37%6%5%5%5%5%7%38%
1665
21st to endNight
13%5%35%435%5%5%9%44%
1980
September1st to 10thNight
14%6%26%5%345%6%7%43%
1800
11th to 20thNight
14%5%24424447%50%
1800
21st to endNight
15%7%25%5%36%46%7%40%
2030
October1st to 10thNight
16%8%36%6%345%5%7%37%
2160
11th to 20thNight
19%8%36%5%3446%7%36%
2160
21st to endNight
24%13%37%6%24446%28%
2438
November1st to 10thNight
12%11%37%6%34446%39%
2407
11th to 20thNight
18%10%46%6%45%5%5%6%32%
2536
21st to endNight
14%13%48%6%346%6%8%28%
2660
December1st to 10thNight
17%15%6%10%7%35%5%5%6%21%
2660
11th to 20thNight
19%14%5%9%7%35%5%5%424%
3288
21st to endNight
24%15%7%9%6%34445%18%
4884

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
62%412%15%6%1
1518
11th to 20thDay
70%5%8%10%6%2
1489
21st to endDay
64%412%12%7%1
1782
February1st to 10thDay
67%6%8%12%6%1
1620
11th to 20thDay
63%5%8%17%7%
1636
21st to endDay
63%410%15%7%1
1480
March1st to 10thDay
58%5%12%18%7%1
1836
11th to 20thDay
59%48%16%10%3
1980
21st to endDay
58%47%16%12%2
2275
April1st to 10thDay
53%6%7%22%10%2
2160
11th to 20thDay
51%5%10%19%14%2
2134
21st to endDay
53%5%8%19%11%4
2160
May1st to 10thDay
53%6%9%19%11%2
2445
11th to 20thDay
51%6%9%21%12%2
2482
21st to endDay
44%8%14%21%11%1
2725
June1st to 10thDay
48%7%11%21%13%1
2520
11th to 20thDay
47%8%12%22%11%1
2520
21st to endDay
44%7%13%25%11%1
2520
July1st to 10thDay
44%8%13%22%12%1
2450
11th to 20thDay
40%7%16%25%12%
2445
21st to endDay
43%9%13%21%13%1
2580
August1st to 10thDay
43%8%15%22%12%1
2314
11th to 20thDay
47%8%12%23%9%
2217
21st to endDay
47%5%11%24%12%1
2376
September1st to 10thDay
46%6%11%23%12%1
2160
11th to 20thDay
40%6%11%22%20%1
2160
21st to endDay
47%5%11%22%13%2
1926
October1st to 10thDay
48%6%11%20%13%1
1800
11th to 20thDay
52%5%10%23%10%1
1800
21st to endDay
60%411%15%8%2
1917
November1st to 10thDay
47%5%13%21%13%2
1671
11th to 20thDay
56%412%18%9%2
1643
21st to endDay
59%5%13%16%5%1
1520
December1st to 10thDay
68%412%10%5%
1520
11th to 20thDay
64%413%14%4
1906
21st to endDay
74%48%10%3
2772
January1st to 10thNight
62%5%13%12%7%1
2649
11th to 20thNight
64%6%13%13%5%1
2578
21st to endNight
64%410%14%7%1
2574
February1st to 10thNight
62%5%12%14%7%
2340
11th to 20thNight
63%411%14%7%1
2221
21st to endNight
59%411%16%9%1
1776
March1st to 10thNight
57%412%18%8%1
2121
11th to 20thNight
55%5%10%19%10%1
1980
21st to endNight
53%5%9%18%13%2
2080
April1st to 10thNight
56%5%9%18%11%2
1800
11th to 20thNight
49%5%11%19%16%1
1775
21st to endNight
50%5%10%20%13%3
1800
May1st to 10thNight
54%5%8%19%12%2
1526
11th to 20thNight
44%8%11%20%15%2
1416
21st to endNight
41%7%14%23%12%2
1551
June1st to 10thNight
43%6%11%25%14%1
1440
11th to 20thNight
41%8%14%25%11%2
1440
21st to endNight
37%7%13%29%13%1
1440
July1st to 10thNight
37%8%15%25%14%2
1400
11th to 20thNight
34%8%17%26%15%1
1392
21st to endNight
40%8%14%21%15%2
1494
August1st to 10thNight
37%7%16%28%11%1
1600
11th to 20thNight
45%8%13%23%10%
1665
21st to endNight
39%6%13%25%16%1
1980
September1st to 10thNight
41%7%13%25%14%2
1800
11th to 20thNight
35%5%11%28%20%1
1800
21st to endNight
43%6%11%24%16%1
2030
October1st to 10thNight
48%7%11%21%12%1
2160
11th to 20thNight
48%5%15%22%9%2
2160
21st to endNight
58%5%12%16%8%1
2438
November1st to 10thNight
46%6%12%20%15%2
2407
11th to 20thNight
53%5%11%19%10%2
2536
21st to endNight
52%8%15%19%6%
2660
December1st to 10thNight
63%7%12%14%4
2660
11th to 20thNight
61%6%11%16%5%
3288
21st to endNight
68%6%11%13%2
4884

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
29%27%31%9%41
180
11th to 20thDay
41%26%25%5%21
174
21st to endDay
27%30%30%10%3
264
February1st to 10thDay
37%32%25%5%
240
11th to 20thDay
37%29%30%3
294
21st to endDay
38%23%27%11%1
346
March1st to 10thDay
34%20%31%11%4
420
11th to 20thDay
36%20%28%11%31
420
21st to endDay
34%24%26%10%32
462
April1st to 10thDay
33%22%27%12%4
420
11th to 20thDay
29%23%27%11%7%3
412
21st to endDay
32%22%27%12%7%1
420
May1st to 10thDay
32%17%28%12%9%3
423
11th to 20thDay
22%16%32%19%9%3
447
21st to endDay
21%12%30%21%13%5%
485
June1st to 10thDay
20%16%31%20%12%1
450
11th to 20thDay
19%14%27%26%12%1
450
21st to endDay
18%13%34%23%9%3
450
July1st to 10thDay
14%7%30%29%15%6%
445
11th to 20thDay
13%7%27%32%18%5%
444
21st to endDay
15%7%36%26%13%3
488
August1st to 10thDay
13%9%28%23%20%7%
446
11th to 20thDay
18%7%25%29%15%8%
439
21st to endDay
13%11%26%26%13%10%
495
September1st to 10thDay
18%12%24%20%18%7%
450
11th to 20thDay
15%10%27%22%17%9%
450
21st to endDay
20%13%29%21%11%5%
450
October1st to 10thDay
24%13%25%20%14%4
450
11th to 20thDay
23%19%29%20%6%1
450
21st to endDay
34%16%28%16%6%
463
November1st to 10thDay
28%15%24%22%9%2
365
11th to 20thDay
31%22%25%14%7%
303
21st to endDay
38%19%33%7%11
180
December1st to 10thDay
35%21%32%8%31
180
11th to 20thDay
36%24%26%13%1
180
21st to endDay
34%28%27%11%1
198
January1st to 10thNight
25%25%32%15%2
760
11th to 20thNight
28%19%29%21%3
741
21st to endNight
19%24%37%18%2
792
February1st to 10thNight
29%20%33%17%1
720
11th to 20thNight
27%24%35%13%1
703
21st to endNight
35%17%32%14%2
592
March1st to 10thNight
27%23%29%18%2
720
11th to 20thNight
28%22%30%16%4
720
21st to endNight
26%21%30%17%5%1
792
April1st to 10thNight
27%22%31%17%3
720
11th to 20thNight
26%19%30%18%7%
711
21st to endNight
26%15%31%22%6%
720
May1st to 10thNight
28%11%25%28%8%
446
11th to 20thNight
17%12%35%27%8%1
354
21st to endNight
13%9%30%34%13%1
389
June1st to 10thNight
19%8%23%36%14%
360
11th to 20thNight
18%8%24%34%14%1
360
21st to endNight
13%5%29%44%9%
360
July1st to 10thNight
9%5%21%45%17%3
350
11th to 20thNight
12%420%43%20%1
348
21st to endNight
15%420%45%14%1
402
August1st to 10thNight
9%422%39%24%2
537
11th to 20thNight
16%414%33%29%4
601
21st to endNight
15%6%19%35%24%2
792
September1st to 10thNight
18%6%24%33%17%3
720
11th to 20thNight
17%6%20%32%21%5%
720
21st to endNight
19%9%25%28%16%3
720
October1st to 10thNight
22%10%25%25%17%2
720
11th to 20thNight
24%14%29%26%6%1
720
21st to endNight
31%16%27%20%5%
792
November1st to 10thNight
20%17%30%25%8%
740
11th to 20thNight
27%18%32%17%5%1
760
21st to endNight
24%18%32%21%4
760
December1st to 10thNight
28%23%29%17%3
760
11th to 20thNight
27%22%30%18%3
760
21st to endNight
29%20%33%16%2
836
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Copyright 2024 Attilla Danko


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