CAMSAT Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the CAMSAT Observatory 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
36%
22805
14%
74887
10%
22761
42%
22761
18%
52301

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
16%
758
10%
2649
4%
757
24%
757
10%
2026
January11th to 20thNight
18%
747
8%
2506
3%
747
24%
747
7%
2065
January21st to endNight
23%
792
12%
2574
6%
792
31%
792
13%
1922
February1st to 10thNight
15%
720
9%
2340
3%
720
24%
720
10%
1829
February11th to 20thNight
19%
701
12%
2275
4%
700
30%
700
12%
1698
February21st to endNight
18%
592
13%
1879
5%
592
29%
592
14%
1375
March1st to 10thNight
26%
720
16%
1980
7%
720
34%
720
20%
1411
March11th to 20thNight
25%
720
16%
1980
8%
720
34%
720
19%
1444
March21st to endNight
34%
792
19%
2178
9%
792
42%
792
23%
1510
April1st to 10thNight
30%
720
16%
1815
6%
720
36%
720
22%
1322
April11th to 20thNight
36%
682
17%
1746
7%
682
41%
682
25%
1245
April21st to endNight
37%
540
16%
1620
7%
540
44%
540
21%
1131
May1st to 10thNight
44%
522
15%
1602
10%
522
49%
522
23%
1068
May11th to 20thNight
46%
354
22%
1416
19%
354
58%
354
24%
815
May21st to endNight
63%
388
18%
1551
21%
388
68%
388
29%
831
June1st to 10thNight
52%
360
14%
1440
15%
360
61%
360
22%
857
June11th to 20thNight
52%
360
15%
1440
20%
360
59%
360
25%
821
June21st to endNight
56%
360
14%
1440
18%
360
62%
360
22%
845
July1st to 10thNight
69%
350
16%
1400
24%
350
73%
350
34%
700
July11th to 20thNight
63%
348
19%
1392
27%
348
66%
348
28%
752
July21st to endNight
67%
522
18%
1607
17%
493
70%
493
33%
925
August1st to 10thNight
66%
537
18%
1600
16%
534
68%
534
34%
946
August11th to 20thNight
68%
534
22%
1598
16%
534
71%
534
36%
926
August21st to endNight
56%
688
21%
1876
12%
688
60%
688
34%
1175
September1st to 10thNight
57%
720
17%
1800
8%
720
60%
720
34%
1192
September11th to 20thNight
57%
720
27%
1874
16%
720
62%
720
39%
1135
September21st to endNight
50%
720
20%
2034
16%
720
53%
720
27%
1342
October1st to 10thNight
42%
720
17%
2160
15%
720
47%
720
23%
1451
October11th to 20thNight
32%
720
14%
2160
10%
720
39%
720
18%
1568
October21st to endNight
28%
792
14%
2376
9%
792
35%
792
16%
1766
November1st to 10thNight
37%
740
19%
2477
15%
740
46%
740
20%
1634
November11th to 20thNight
28%
760
14%
2660
8%
760
37%
760
15%
1885
November21st to endNight
25%
760
10%
2660
6%
760
30%
760
12%
1985
December1st to 10thNight
19%
760
8%
2660
4%
760
23%
760
9%
2095
December11th to 20thNight
18%
759
7%
3256
2%
759
24%
759
7%
2514
December21st to endNight
14%
827
3%
4866
1%
817
20%
817
4%
4095

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
15%8%37%6%45%5%6%7%34%
74701
Night
16%9%36%6%35%5%5%7%35%
75116
TransparencyDay
46%8%14%20%11%1
74414
Night
49%7%12%20%11%1
74937
SeeingDay
17%9%27%28%14%4
13320
Night
19%8%29%29%13%2
22820

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
15%13%48%7%5%5%45%6%27%
1517
11th to 20thDay
17%15%5%9%7%5%5%5%46%22%
1589
21st to endDay
13%12%7%11%8%5%5%5%5%6%23%
1782
February1st to 10thDay
16%14%5%10%8%46%5%5%5%20%
1620
11th to 20thDay
13%12%7%11%6%45%446%28%
1573
21st to endDay
19%13%5%9%6%45%445%28%
1374
March1st to 10thDay
14%10%38%8%46%46%7%31%
1977
11th to 20thDay
14%10%6%8%6%4445%6%34%
1980
21st to endDay
18%9%46%6%34446%36%
2178
April1st to 10thDay
18%9%5%8%6%345%5%7%30%
2144
11th to 20thDay
19%8%36%5%35%5%46%37%
2178
21st to endDay
20%7%46%5%35%5%5%6%34%
2340
May1st to 10thDay
16%8%47%5%35%5%6%8%33%
2357
11th to 20thDay
14%7%35%6%245%6%8%41%
2478
21st to endDay
11%5%25%5%35%5%7%8%44%
2725
June1st to 10thDay
14%6%36%5%446%8%8%37%
2520
11th to 20thDay
11%6%26%5%36%5%7%10%40%
2520
21st to endDay
13%5%25%5%35%47%9%41%
2520
July1st to 10thDay
8%415%5%36%6%6%9%47%
2520
11th to 20thDay
10%425%5%45%7%7%10%41%
2520
21st to endDay
8%5%26%6%46%7%7%10%38%
2613
August1st to 10thDay
8%426%6%46%6%7%9%41%
2327
11th to 20thDay
8%426%6%35%6%7%11%41%
2303
21st to endDay
10%6%35%5%35%5%7%8%42%
2462
September1st to 10thDay
13%426%435%6%6%7%43%
2160
11th to 20thDay
12%5%245%35%46%8%47%
2084
21st to endDay
12%5%36%6%35%5%6%8%40%
1926
October1st to 10thDay
17%7%36%6%45%5%5%6%36%
1800
11th to 20thDay
20%8%36%6%45%5%6%6%31%
1800
21st to endDay
23%10%48%6%45%5%5%6%25%
1980
November1st to 10thDay
15%8%37%6%46%45%8%33%
1596
11th to 20thDay
15%10%48%7%5%5%6%6%7%26%
1520
21st to endDay
20%11%47%7%35%45%9%24%
1520
December1st to 10thDay
18%12%6%10%8%46%6%5%7%18%
1520
11th to 20thDay
19%12%5%7%6%35%5%5%7%26%
1906
21st to endDay
29%15%5%11%7%4443414%
2772
January1st to 10thNight
17%13%5%8%6%45%5%5%6%26%
2649
11th to 20thNight
20%13%6%9%7%46%5%5%6%20%
2506
21st to endNight
13%11%5%8%8%46%5%5%7%29%
2574
February1st to 10thNight
14%15%6%8%8%46%5%5%6%24%
2340
11th to 20thNight
15%11%5%9%7%45%5%5%6%28%
2273
21st to endNight
15%11%5%8%6%45%5%5%6%30%
1879
March1st to 10thNight
14%7%46%7%46%5%45%36%
1970
11th to 20thNight
17%10%6%6%6%44445%34%
1979
21st to endNight
16%7%45%5%35%446%41%
2178
April1st to 10thNight
19%10%36%5%346%5%7%34%
1815
11th to 20thNight
15%6%37%6%45%5%5%6%39%
1746
21st to endNight
17%8%36%6%35%5%6%7%36%
1620
May1st to 10thNight
17%5%25%6%35%6%5%7%39%
1602
11th to 20thNight
13%426%425%5%5%7%45%
1415
21st to endNight
10%4245%3446%8%52%
1550
June1st to 10thNight
11%5%25%5%46%5%6%8%43%
1440
11th to 20thNight
8%5%26%6%446%5%9%44%
1440
21st to endNight
12%5%245%35%46%9%44%
1440
July1st to 10thNight
5%4245%3446%8%57%
1440
11th to 20thNight
9%425%5%3446%8%49%
1440
21st to endNight
9%4244345%7%9%50%
1702
August1st to 10thNight
8%415%5%2447%8%50%
1611
11th to 20thNight
7%4246%245%5%9%51%
1598
21st to endNight
10%426%5%3446%7%49%
1876
September1st to 10thNight
10%5%35%5%45%6%6%7%46%
1800
11th to 20thNight
11%42443335%7%54%
1874
21st to endNight
15%6%36%5%245%6%6%44%
2034
October1st to 10thNight
15%7%26%6%345%5%6%39%
2160
11th to 20thNight
20%8%35%6%345%6%6%32%
2160
21st to endNight
22%9%46%5%36%6%5%6%29%
2376
November1st to 10thNight
17%7%35%6%35%5%5%7%38%
2477
11th to 20thNight
16%9%37%6%46%5%6%8%30%
2660
21st to endNight
20%10%37%6%35%5%6%8%27%
2660
December1st to 10thNight
20%12%5%8%7%36%6%5%5%23%
2660
11th to 20thNight
17%15%5%8%6%45%6%5%6%23%
3288
21st to endNight
30%13%5%8%5%45%5%5%5%15%
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
57%10%14%13%6%
1518
11th to 20thDay
64%9%10%10%6%
1589
21st to endDay
62%8%11%12%7%1
1782
February1st to 10thDay
64%8%10%14%41
1620
11th to 20thDay
57%7%12%16%7%1
1582
21st to endDay
58%6%12%18%6%
1374
March1st to 10thDay
51%8%15%16%10%1
1980
11th to 20thDay
51%7%11%16%12%2
1980
21st to endDay
49%5%10%18%15%3
2178
April1st to 10thDay
51%7%12%17%10%2
2144
11th to 20thDay
47%6%11%20%14%1
2178
21st to endDay
48%7%12%18%12%3
2340
May1st to 10thDay
46%7%12%19%14%2
2357
11th to 20thDay
41%8%11%25%14%2
2482
21st to endDay
36%8%17%24%13%2
2725
June1st to 10thDay
41%9%14%21%14%1
2520
11th to 20thDay
37%8%13%25%15%2
2520
21st to endDay
36%8%17%23%14%1
2520
July1st to 10thDay
29%9%14%26%19%3
2450
11th to 20thDay
34%9%16%30%10%1
2445
21st to endDay
36%11%16%24%12%1
2467
August1st to 10thDay
34%11%17%24%13%1
2314
11th to 20thDay
33%10%18%27%12%1
2303
21st to endDay
34%9%15%28%12%1
2462
September1st to 10thDay
36%10%14%28%11%1
2160
11th to 20thDay
32%9%15%29%14%1
2084
21st to endDay
40%9%15%27%9%1
1926
October1st to 10thDay
47%8%15%18%11%1
1800
11th to 20thDay
51%8%14%19%7%1
1800
21st to endDay
58%7%14%15%5%1
1980
November1st to 10thDay
48%8%15%19%9%1
1596
11th to 20thDay
53%9%15%14%8%1
1520
21st to endDay
57%8%15%16%3
1520
December1st to 10thDay
64%9%13%11%3
1520
11th to 20thDay
57%11%14%11%6%
1906
21st to endDay
72%9%8%10%2
2772
January1st to 10thNight
60%7%12%15%6%
2649
11th to 20thNight
66%9%9%10%5%1
2506
21st to endNight
56%7%14%15%7%1
2574
February1st to 10thNight
60%9%11%16%41
2340
11th to 20thNight
58%6%12%16%8%1
2275
21st to endNight
54%8%12%19%8%1
1879
March1st to 10thNight
49%6%14%19%10%2
1980
11th to 20thNight
52%5%10%20%11%2
1980
21st to endNight
46%5%9%22%15%3
2178
April1st to 10thNight
50%411%20%14%1
1815
11th to 20thNight
46%6%10%19%16%2
1746
21st to endNight
47%8%10%19%14%2
1620
May1st to 10thNight
44%7%10%20%16%3
1602
11th to 20thNight
38%6%11%24%18%4
1416
21st to endNight
31%6%15%24%19%4
1551
June1st to 10thNight
38%8%11%24%16%2
1440
11th to 20thNight
37%6%12%22%22%2
1440
21st to endNight
37%8%13%24%17%1
1440
July1st to 10thNight
27%6%13%26%24%4
1400
11th to 20thNight
32%7%12%30%18%2
1392
21st to endNight
30%8%14%29%16%2
1607
August1st to 10thNight
31%7%18%28%14%2
1600
11th to 20thNight
30%7%16%32%14%1
1598
21st to endNight
34%7%13%29%16%1
1876
September1st to 10thNight
35%8%15%26%14%2
1800
11th to 20thNight
30%6%13%33%18%
1874
21st to endNight
40%7%13%27%13%
2034
October1st to 10thNight
44%7%12%22%15%1
2160
11th to 20thNight
51%8%13%21%7%
2160
21st to endNight
54%7%12%16%10%
2376
November1st to 10thNight
45%7%12%22%13%1
2477
11th to 20thNight
51%8%15%16%10%1
2660
21st to endNight
55%9%17%15%4
2660
December1st to 10thNight
61%9%11%14%4
2660
11th to 20thNight
61%8%13%14%4
3288
21st to endNight
69%11%11%8%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
23%18%31%18%9%1
180
11th to 20thDay
23%21%33%15%6%
218
21st to endDay
22%19%34%21%4
264
February1st to 10thDay
24%23%35%15%3
240
11th to 20thDay
22%21%39%16%3
240
21st to endDay
27%24%31%17%2
232
March1st to 10thDay
20%14%38%22%6%
420
11th to 20thDay
20%16%34%23%7%
420
21st to endDay
25%11%32%23%7%1
462
April1st to 10thDay
18%15%32%29%6%
420
11th to 20thDay
24%9%29%23%12%3
412
21st to endDay
22%10%34%22%10%2
420
May1st to 10thDay
22%7%25%29%11%6%
423
11th to 20thDay
16%424%34%18%4
447
21st to endDay
14%321%36%21%6%
485
June1st to 10thDay
13%5%27%36%16%2
450
11th to 20thDay
13%423%35%22%2
450
21st to endDay
14%321%39%18%5%
450
July1st to 10thDay
8%218%35%31%7%
445
11th to 20thDay
13%217%36%24%8%
444
21st to endDay
8%323%40%20%6%
488
August1st to 10thDay
9%217%36%25%11%
446
11th to 20thDay
10%316%31%30%9%
439
21st to endDay
11%320%35%22%9%
495
September1st to 10thDay
12%421%32%21%10%
450
11th to 20thDay
10%417%34%22%14%
450
21st to endDay
13%6%29%29%15%8%
450
October1st to 10thDay
20%8%25%25%16%6%
450
11th to 20thDay
20%14%33%24%8%1
450
21st to endDay
26%14%30%22%8%
495
November1st to 10thDay
20%15%28%24%11%1
267
11th to 20thDay
18%20%32%24%6%1
180
21st to endDay
25%13%39%18%5%1
180
December1st to 10thDay
21%16%35%21%6%2
180
11th to 20thDay
23%24%31%17%5%
180
21st to endDay
28%19%39%13%2
198
January1st to 10thNight
24%14%38%18%6%
760
11th to 20thNight
27%14%33%23%31
747
21st to endNight
19%10%37%27%6%1
792
February1st to 10thNight
21%15%40%21%3
720
11th to 20thNight
22%14%37%22%6%
703
21st to endNight
21%13%41%20%4
592
March1st to 10thNight
18%12%37%28%5%1
720
11th to 20thNight
21%12%35%26%6%1
720
21st to endNight
20%8%31%29%12%1
792
April1st to 10thNight
24%10%31%29%7%
720
11th to 20thNight
16%10%31%30%11%1
682
21st to endNight
21%6%29%32%11%
540
May1st to 10thNight
19%327%31%18%2
522
11th to 20thNight
16%129%37%17%1
354
21st to endNight
10%218%44%24%2
389
June1st to 10thNight
13%323%41%19%1
360
11th to 20thNight
10%324%40%21%2
360
21st to endNight
12%320%41%23%1
360
July1st to 10thNight
6%215%45%30%2
350
11th to 20thNight
12%316%41%26%3
348
21st to endNight
9%215%47%24%3
522
August1st to 10thNight
10%112%40%32%4
537
11th to 20thNight
7%214%39%32%5%
534
21st to endNight
11%221%37%26%4
688
September1st to 10thNight
10%5%21%34%24%6%
720
11th to 20thNight
13%419%29%27%7%
720
21st to endNight
17%5%20%31%22%5%
720
October1st to 10thNight
18%5%28%27%20%2
720
11th to 20thNight
23%11%28%28%9%1
720
21st to endNight
26%9%29%29%6%1
792
November1st to 10thNight
21%9%25%32%11%1
740
11th to 20thNight
21%14%30%27%7%2
760
21st to endNight
24%10%33%25%7%
760
December1st to 10thNight
29%12%33%21%4
760
11th to 20thNight
21%13%38%23%41
760
21st to endNight
31%11%36%20%2
836
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Copyright 2024 Attilla Danko


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