Cloudbait Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cloudbait Observatory clear sky chart from 2005-11-06 to 2024-02-20.

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
43%
24648
28%
79710
14%
24536
58%
24536
39%
40222

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
34%
947
33%
4325
13%
926
54%
926
30%
1919
January11th to 20thNight
29%
844
40%
4100
14%
826
52%
826
36%
1447
January21st to endNight
35%
830
24%
4288
16%
814
59%
814
30%
1819
February1st to 10thNight
24%
760
32%
2470
10%
760
50%
760
42%
1172
February11th to 20thNight
28%
742
30%
2236
9%
738
49%
738
38%
1166
February21st to endNight
27%
592
38%
1776
10%
592
56%
592
42%
891
March1st to 10thNight
32%
720
30%
2147
9%
720
52%
720
44%
1069
March11th to 20thNight
38%
720
28%
1980
12%
720
49%
720
41%
1105
March21st to endNight
30%
680
30%
2066
9%
680
51%
680
36%
1115
April1st to 10thNight
29%
540
28%
1800
10%
540
52%
540
35%
874
April11th to 20thNight
33%
533
25%
1777
12%
533
50%
533
31%
956
April21st to endNight
35%
540
24%
1800
12%
540
53%
540
32%
964
May1st to 10thNight
39%
540
22%
1746
15%
540
49%
540
30%
994
May11th to 20thNight
45%
531
15%
1432
12%
531
49%
531
30%
923
May21st to endNight
43%
583
20%
1552
10%
582
53%
582
36%
934
June1st to 10thNight
60%
540
23%
1440
14%
540
67%
540
46%
777
June11th to 20thNight
60%
540
26%
1440
19%
540
66%
540
51%
757
June21st to endNight
66%
540
24%
1440
19%
540
70%
540
43%
794
July1st to 10thNight
66%
525
17%
1400
15%
525
67%
525
32%
898
July11th to 20thNight
71%
522
23%
1392
21%
522
72%
522
44%
793
July21st to endNight
68%
591
12%
1607
11%
558
70%
558
26%
1042
August1st to 10thNight
64%
537
13%
1602
12%
534
66%
534
26%
1012
August11th to 20thNight
68%
534
22%
1778
23%
534
71%
534
32%
1003
August21st to endNight
69%
594
24%
1980
25%
594
72%
594
33%
1099
September1st to 10thNight
62%
540
27%
1800
22%
540
71%
540
33%
1004
September11th to 20thNight
63%
540
34%
1804
30%
540
72%
540
44%
888
September21st to endNight
56%
545
31%
1985
23%
545
68%
545
40%
949
October1st to 10thNight
50%
720
29%
2160
16%
720
61%
720
43%
1147
October11th to 20thNight
50%
720
38%
2160
17%
720
67%
720
59%
975
October21st to endNight
45%
792
37%
2376
16%
792
61%
792
46%
1182
November1st to 10thNight
43%
925
35%
2405
15%
925
56%
925
58%
1197
November11th to 20thNight
37%
950
39%
2470
14%
950
54%
950
53%
1231
November21st to endNight
41%
950
34%
2546
13%
950
56%
950
49%
1305
December1st to 10thNight
35%
950
30%
2660
11%
950
51%
950
45%
1340
December11th to 20thNight
31%
949
31%
3109
11%
949
49%
949
41%
1465
December21st to endNight
26%
1042
20%
4661
9%
1026
46%
1026
29%
2016

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
35%25%5%35%5%6%8%53%
78492
Night
242443445%8%58%
80762
TransparencyDay
27%5%11%24%23%9%
78204
Night
23%5%13%27%25%8%
80572
SeeingDay
8%17%31%26%14%3
14447
Night
5%11%35%36%12%1
24664

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
3244245%6%9%61%
2538
11th to 20thDay
1215%42447%10%60%
2736
21st to endDay
6%36%5%2446%9%55%
3146
February1st to 10thDay
15%45%42346%7%60%
1710
11th to 20thDay
12134235%6%10%63%
1815
21st to endDay
426%6%24448%59%
1480
March1st to 10thDay
1435%435%45%8%59%
1808
11th to 20thDay
26%36%435%45%9%51%
1980
21st to endDay
26%35%5%345%6%9%51%
2290
April1st to 10thDay
26%245%35%6%6%9%52%
2160
11th to 20thDay
49%37%6%3445%7%47%
2131
21st to endDay
5%8%26%5%45%5%7%8%44%
2160
May1st to 10thDay
6%7%37%6%45%6%7%8%41%
2214
11th to 20thDay
5%8%38%7%46%6%7%10%36%
2460
21st to endDay
45%36%5%46%6%7%9%45%
2724
June1st to 10thDay
35%25%5%46%6%8%11%46%
2520
11th to 20thDay
45%24435%6%7%8%53%
2520
21st to endDay
3325%6%46%8%7%9%46%
2520
July1st to 10thDay
6%426%6%46%8%7%9%43%
2520
11th to 20thDay
5%5%36%6%47%5%6%9%45%
2520
21st to endDay
7%7%37%8%5%7%8%8%10%31%
2612
August1st to 10thDay
8%6%36%8%47%7%7%8%36%
2327
11th to 20thDay
6%325%6%46%6%7%9%45%
2123
21st to endDay
6%5%25%6%35%6%6%9%46%
2376
September1st to 10thDay
6%5%25%5%45%5%6%7%50%
2160
11th to 20thDay
5%325%5%345%5%7%56%
2156
21st to endDay
5%414434345%63%
1972
October1st to 10thDay
44245%345%6%7%57%
1800
11th to 20thDay
2313323346%70%
1800
21st to endDay
46%24324445%64%
1961
November1st to 10thDay
1313312447%71%
1673
11th to 20thDay
322323348%70%
1710
21st to endDay
325%433447%65%
1630
December1st to 10thDay
325%3235%5%8%65%
1520
11th to 20thDay
132332436%11%62%
1926
21st to endDay
1325%43345%9%62%
2794
January1st to 10thNight
336%4345%6%8%58%
4417
11th to 20thNight
1212225%5%5%8%68%
4261
21st to endNight
5%25%43345%7%59%
4521
February1st to 10thNight
335%42335%7%64%
2470
11th to 20thNight
1426%43445%6%62%
2236
21st to endNight
5%25%32335%7%64%
1776
March1st to 10thNight
142433335%8%63%
2147
11th to 20thNight
25%35%5%3346%8%56%
1980
21st to endNight
26%35%5%35%45%7%57%
2066
April1st to 10thNight
26%35%32335%7%63%
1800
11th to 20thNight
47%36%5%34448%52%
1777
21st to endNight
48%345%25%45%8%51%
1800
May1st to 10thNight
7%8%45%43445%7%48%
1746
11th to 20thNight
5%10%36%6%36%5%6%8%42%
1432
21st to endNight
7%6%25%5%345%6%7%50%
1552
June1st to 10thNight
3423335%5%6%10%56%
1440
11th to 20thNight
331333445%9%61%
1440
21st to endNight
33245%27%6%7%8%54%
1440
July1st to 10thNight
6%427%5%47%7%7%10%41%
1440
11th to 20thNight
4435%5%345%6%9%53%
1440
21st to endNight
5%5%36%7%5%8%8%9%12%33%
1702
August1st to 10thNight
5%5%37%5%5%6%7%8%9%41%
1611
11th to 20thNight
6%435%6%35%5%7%7%49%
1778
21st to endNight
45%25%5%46%6%6%10%47%
1980
September1st to 10thNight
6%435%5%35%6%6%9%47%
1800
11th to 20thNight
5%5%2331446%8%59%
1804
21st to endNight
5%424433447%61%
1985
October1st to 10thNight
5%5%244245%5%6%60%
2160
11th to 20thNight
131231335%5%73%
2160
21st to endNight
342432345%7%64%
2376
November1st to 10thNight
1214322347%70%
2405
11th to 20thNight
213423346%72%
2470
21st to endNight
15%2432335%8%65%
2546
December1st to 10thNight
122433445%8%65%
2660
11th to 20thNight
13243235%6%10%60%
3271
21st to endNight
1425%43345%8%61%
4873

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
17%5%13%32%24%8%
2539
11th to 20thDay
19%314%33%24%7%
2736
21st to endDay
25%412%32%22%6%
3146
February1st to 10thDay
22%5%12%30%21%10%
1710
11th to 20thDay
17%5%10%29%31%9%
1825
21st to endDay
24%5%8%23%27%13%
1480
March1st to 10thDay
24%39%28%29%8%
1808
11th to 20thDay
28%5%10%26%25%5%
1980
21st to endDay
29%5%10%26%23%5%
2290
April1st to 10thDay
27%6%11%24%21%11%
2160
11th to 20thDay
36%48%25%20%7%
2134
21st to endDay
35%6%10%25%21%4
2160
May1st to 10thDay
38%7%11%22%17%4
2214
11th to 20thDay
41%7%17%20%13%2
2464
21st to endDay
32%7%13%21%18%8%
2724
June1st to 10thDay
29%8%15%20%20%8%
2520
11th to 20thDay
27%5%8%18%24%18%
2520
21st to endDay
30%7%10%22%21%11%
2520
July1st to 10thDay
33%8%12%16%20%11%
2451
11th to 20thDay
33%6%14%24%16%7%
2445
21st to endDay
43%9%19%16%11%2
2467
August1st to 10thDay
41%8%16%14%14%7%
2312
11th to 20thDay
32%6%12%20%20%10%
2123
21st to endDay
32%5%12%22%22%6%
2376
September1st to 10thDay
31%5%9%18%24%13%
2160
11th to 20thDay
27%5%9%19%28%13%
2156
21st to endDay
23%46%25%33%9%
1972
October1st to 10thDay
25%5%10%20%28%12%
1800
11th to 20thDay
17%36%23%36%16%
1800
21st to endDay
22%47%27%28%12%
1961
November1st to 10thDay
13%310%23%36%14%
1673
11th to 20thDay
15%36%36%30%9%
1710
21st to endDay
20%38%27%29%13%
1630
December1st to 10thDay
18%5%15%30%24%8%
1520
11th to 20thDay
17%414%32%27%7%
1924
21st to endDay
18%6%9%28%27%12%
2794
January1st to 10thNight
22%5%11%31%28%4
4417
11th to 20thNight
14%413%31%30%8%
4261
21st to endNight
23%315%31%23%4
4521
February1st to 10thNight
20%411%34%23%8%
2470
11th to 20thNight
23%5%9%29%26%7%
2236
21st to endNight
20%5%7%28%31%10%
1776
March1st to 10thNight
19%410%27%31%7%
2147
11th to 20thNight
26%5%11%32%23%4
1980
21st to endNight
26%5%11%28%26%4
2066
April1st to 10thNight
23%412%28%26%8%
1800
11th to 20thNight
30%411%29%21%5%
1777
21st to endNight
29%5%16%28%18%4
1800
May1st to 10thNight
33%5%13%26%18%5%
1746
11th to 20thNight
38%6%17%21%15%2
1433
21st to endNight
31%6%15%22%18%7%
1552
June1st to 10thNight
23%5%21%25%14%12%
1440
11th to 20thNight
19%5%12%22%24%18%
1440
21st to endNight
24%7%12%24%21%12%
1440
July1st to 10thNight
34%9%14%19%16%8%
1400
11th to 20thNight
26%6%18%30%14%6%
1392
21st to endNight
38%10%26%19%7%1
1607
August1st to 10thNight
36%10%18%17%13%5%
1602
11th to 20thNight
31%7%16%23%18%5%
1778
21st to endNight
30%7%14%27%17%4
1980
September1st to 10thNight
30%7%11%22%21%9%
1800
11th to 20thNight
23%412%23%24%14%
1804
21st to endNight
24%49%27%29%7%
1985
October1st to 10thNight
24%5%12%24%25%10%
2160
11th to 20thNight
13%48%23%38%14%
2160
21st to endNight
20%48%29%29%10%
2376
November1st to 10thNight
14%410%28%30%13%
2405
11th to 20thNight
14%47%34%30%10%
2470
21st to endNight
19%39%27%30%12%
2546
December1st to 10thNight
18%5%15%29%26%8%
2660
11th to 20thNight
18%414%28%30%6%
3272
21st to endNight
22%412%25%28%9%
4873

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
7%21%31%31%9%1
270
11th to 20thDay
12%20%40%25%21
270
21st to endDay
418%44%26%7%2
297
February1st to 10thDay
338%39%17%21
270
11th to 20thDay
5%30%44%16%4
267
21st to endDay
7%35%39%15%4
198
March1st to 10thDay
5%29%38%23%6%
248
11th to 20thDay
8%29%38%21%5%
420
21st to endDay
13%33%39%13%2
462
April1st to 10thDay
14%30%36%16%5%
420
11th to 20thDay
21%30%31%13%41
412
21st to endDay
16%30%32%15%5%1
420
May1st to 10thDay
12%24%34%21%7%1
477
11th to 20thDay
10%17%29%31%11%3
625
21st to endDay
9%16%29%28%15%3
679
June1st to 10thDay
5%14%28%28%21%4
630
11th to 20thDay
7%13%31%30%16%4
630
21st to endDay
311%31%27%21%5%
630
July1st to 10thDay
7%5%20%34%30%5%
621
11th to 20thDay
8%218%34%29%8%
618
21st to endDay
10%5%18%33%28%7%
554
August1st to 10thDay
11%7%22%36%19%6%
447
11th to 20thDay
8%8%24%35%19%6%
437
21st to endDay
8%6%28%34%19%4
495
September1st to 10thDay
8%8%28%31%21%3
450
11th to 20thDay
7%10%33%33%14%4
446
21st to endDay
6%14%20%31%24%5%
270
October1st to 10thDay
6%16%28%23%22%5%
270
11th to 20thDay
6%17%31%26%18%1
270
21st to endDay
11%19%35%25%9%1
297
November1st to 10thDay
8%17%37%24%12%2
270
11th to 20thDay
6%20%37%27%8%3
270
21st to endDay
318%46%24%9%
270
December1st to 10thDay
9%19%40%24%7%1
270
11th to 20thDay
324%44%24%6%
270
21st to endDay
8%24%42%20%41
297
January1st to 10thNight
217%41%30%9%1
950
11th to 20thNight
320%45%25%7%1
846
21st to endNight
113%44%35%5%1
836
February1st to 10thNight
215%54%26%3
760
11th to 20thNight
216%50%29%3
742
21st to endNight
316%51%28%3
592
March1st to 10thNight
315%45%32%5%
720
11th to 20thNight
5%12%40%35%9%
720
21st to endNight
5%16%46%30%4
680
April1st to 10thNight
6%18%42%31%4
540
11th to 20thNight
9%16%36%32%7%
533
21st to endNight
10%14%37%31%8%
540
May1st to 10thNight
11%11%32%37%8%1
540
11th to 20thNight
11%7%29%37%14%2
531
21st to endNight
10%9%30%35%15%1
584
June1st to 10thNight
6%425%43%19%2
540
11th to 20thNight
5%428%48%14%2
540
21st to endNight
4320%44%27%2
540
July1st to 10thNight
6%314%41%33%3
525
11th to 20thNight
5%211%43%34%4
522
21st to endNight
6%28%39%41%4
591
August1st to 10thNight
8%413%40%33%3
537
11th to 20thNight
7%214%44%30%3
534
21st to endNight
7%212%46%30%3
594
September1st to 10thNight
6%417%46%23%5%
540
11th to 20thNight
8%221%47%19%2
540
21st to endNight
6%5%26%43%18%2
545
October1st to 10thNight
5%7%33%40%13%2
720
11th to 20thNight
35%38%40%13%1
720
21st to endNight
6%9%35%36%12%2
792
November1st to 10thNight
310%39%38%10%1
925
11th to 20thNight
316%42%32%7%1
950
21st to endNight
314%38%37%8%
950
December1st to 10thNight
315%43%34%5%
950
11th to 20thNight
216%45%31%5%1
950
21st to endNight
320%45%28%4
1045
Page generated at 2024-02-17 04:28:40. Version ac07

Copyright 2024 Attilla Danko


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