Cloudbait Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cloudbait Observatory clear sky chart from 2005-11-05 to 2017-12-04.

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
47%
16229
28%
47837
15%
16183
59%
16183
40%
25340

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
37%
894
31%
2500
14%
889
54%
889
45%
1228
January16th to endNight
37%
768
35%
2496
17%
768
59%
768
46%
1114
February1st to 15thNight
31%
703
27%
2247
10%
699
50%
699
38%
1120
February16th to endNight
32%
632
35%
1894
11%
632
56%
632
44%
929
March1st to 15thNight
38%
720
29%
2091
11%
720
53%
720
43%
1069
March16th to endNight
35%
692
29%
2036
12%
692
51%
692
38%
1101
April1st to 15thNight
36%
539
25%
1798
12%
539
54%
539
34%
896
April16th to endNight
35%
540
23%
1800
12%
540
51%
540
29%
1004
May1st to 15thNight
41%
539
20%
1653
15%
539
49%
539
28%
1011
May16th to endNight
45%
562
18%
1497
10%
561
53%
561
35%
912
June1st to 15thNight
61%
540
23%
1440
15%
540
67%
540
48%
771
June16th to endNight
70%
540
25%
1440
20%
540
74%
540
50%
750
July1st to 15thNight
67%
510
16%
1360
14%
510
68%
510
30%
898
July16th to endNight
69%
564
14%
1492
14%
531
70%
531
31%
938
August1st to 15thNight
68%
539
15%
1671
15%
536
69%
536
28%
1026
August16th to endNight
69%
573
23%
1910
25%
573
72%
573
30%
1096
September1st to 15thNight
65%
540
24%
1800
22%
540
71%
540
33%
1020
September16th to endNight
60%
541
33%
1927
27%
541
70%
541
42%
922
October1st to 15thNight
54%
720
31%
2160
18%
720
64%
720
46%
1114
October16th to endNight
55%
768
38%
2304
21%
768
68%
768
48%
1135
November1st to 15thNight
49%
950
34%
2470
17%
950
58%
950
53%
1255
November16th to endNight
46%
975
39%
2587
17%
975
61%
975
54%
1267
December1st to 15thNight
35%
920
26%
2576
9%
920
50%
920
41%
1325
December16th to endNight
33%
960
28%
2688
11%
960
49%
960
38%
1439

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
45%25%5%345%5%8%51%
48662
Night
242432445%7%57%
48018
TransparencyDay
29%5%12%25%21%6%
48344
Night
24%414%28%22%6%
47838
SeeingDay
10%16%29%25%15%4
6034
Night
5%10%30%36%15%1
16232

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
323323347%64%
1447
16th to endDay
131431335%6%64%
1728
February1st to 15thDay
1425%31345%9%57%
1615
16th to endDay
42441345%8%59%
1580
March1st to 15thDay
1435%425%45%8%54%
1866
16th to endDay
26%35%43445%9%50%
2187
April1st to 15thDay
27%145%35%45%9%49%
2150
16th to endDay
6%10%36%5%3445%6%42%
2160
May1st to 15thDay
7%7%37%6%45%5%6%8%37%
2295
16th to endDay
46%36%5%45%5%6%8%42%
2616
June1st to 15thDay
45%24435%5%6%9%47%
2520
16th to endDay
3215%5%35%6%6%7%52%
2520
July1st to 15thDay
7%427%5%46%7%6%9%39%
2520
16th to endDay
6%6%35%6%47%7%7%8%34%
2570
August1st to 15thDay
9%5%35%7%36%6%6%8%36%
2278
16th to endDay
7%425%6%35%6%6%8%42%
2292
September1st to 15thDay
6%5%26%5%35%5%6%7%45%
2160
16th to endDay
432443333460%
2031
October1st to 15thDay
332442345%7%59%
1800
16th to endDay
3413313345%64%
1907
November1st to 15thDay
313212347%67%
1718
16th to endDay
113422347%68%
1700
December1st to 15thDay
324323448%60%
1466
16th to endDay
131422246%11%57%
1536
January1st to 15thNight
213223447%67%
2500
16th to endNight
313223336%69%
2496
February1st to 15thNight
43432245%7%60%
2237
16th to endNight
41332335%7%63%
1894
March1st to 15thNight
42432345%8%60%
2091
16th to endNight
25%24324346%58%
2036
April1st to 15thNight
26%24323348%58%
1798
16th to endNight
6%7%35%5%2445%7%48%
1800
May1st to 15thNight
7%8%36%425%45%7%43%
1652
16th to endNight
5%6%245%35%46%7%47%
1497
June1st to 15thNight
2213324448%60%
1440
16th to endNight
1113325%5%6%8%60%
1440
July1st to 15thNight
6%436%5%46%6%7%9%39%
1440
16th to endNight
44346%47%6%8%11%38%
1595
August1st to 15thNight
5%426%5%45%6%7%7%44%
1680
16th to endNight
5%4345%45%6%6%9%45%
1910
September1st to 15thNight
6%425%425%5%7%9%45%
1800
16th to endNight
5%313323447%60%
1927
October1st to 15thNight
331331345%5%64%
2160
16th to endNight
3313323446%63%
2304
November1st to 15thNight
213323347%67%
2470
16th to endNight
31221225%7%68%
2587
December1st to 15thNight
223333347%63%
2576
16th to endNight
425%42335%8%59%
2688

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
19%318%34%19%4
1448
16th to endDay
19%314%34%22%6%
1728
February1st to 15thDay
22%314%36%18%4
1616
16th to endDay
22%310%30%26%5%
1580
March1st to 15thDay
26%211%27%25%5%
1866
16th to endDay
30%5%11%26%22%3
2187
April1st to 15thDay
30%411%28%17%6%
2150
16th to endDay
40%410%22%19%3
2160
May1st to 15thDay
41%7%13%20%16%1
2295
16th to endDay
35%6%15%21%15%5%
2620
June1st to 15thDay
29%6%12%17%21%11%
2520
16th to endDay
26%5%8%21%25%11%
2520
July1st to 15thDay
37%7%12%18%15%8%
2371
16th to endDay
40%8%18%18%11%2
2410
August1st to 15thDay
41%7%14%15%14%6%
2263
16th to endDay
35%6%11%24%17%4
2292
September1st to 15thDay
35%411%20%20%7%
2160
16th to endDay
25%38%25%30%6%
2031
October1st to 15thDay
23%49%24%29%8%
1800
16th to endDay
21%28%28%30%8%
1907
November1st to 15thDay
16%310%27%29%11%
1718
16th to endDay
16%27%34%30%9%
1700
December1st to 15thDay
21%418%32%19%4
1466
16th to endDay
19%6%19%30%19%5%
1536
January1st to 15thNight
16%418%32%24%3
2500
16th to endNight
16%312%32%26%7%
2496
February1st to 15thNight
22%414%38%17%3
2247
16th to endNight
19%29%33%28%6%
1894
March1st to 15thNight
21%313%31%26%4
2091
16th to endNight
25%412%32%22%3
2036
April1st to 15thNight
24%313%31%21%5%
1798
16th to endNight
33%314%27%16%3
1800
May1st to 15thNight
38%414%24%16%3
1653
16th to endNight
32%5%16%24%15%5%
1498
June1st to 15thNight
21%5%18%22%17%15%
1440
16th to endNight
19%5%12%24%23%13%
1440
July1st to 15thNight
37%8%14%19%12%7%
1360
16th to endNight
34%8%25%20%8%2
1492
August1st to 15thNight
34%8%17%18%14%5%
1671
16th to endNight
32%6%16%25%15%3
1910
September1st to 15thNight
31%6%15%21%16%7%
1800
16th to endNight
23%311%30%26%5%
1927
October1st to 15thNight
20%5%10%25%29%8%
2160
16th to endNight
20%38%28%31%7%
2304
November1st to 15thNight
16%311%28%29%11%
2470
16th to endNight
14%39%34%29%8%
2587
December1st to 15thNight
20%418%32%21%3
2576
16th to endNight
22%418%28%20%4
2688

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
10%21%21%30%16%1
90
16th to endDay
6%11%39%36%6%
96
February1st to 15thDay
6%32%40%18%2
90
16th to endDay
28%35%23%11%1
81
March1st to 15thDay
6%25%39%21%7%
156
16th to endDay
11%38%34%13%2
288
April1st to 15thDay
14%36%28%14%5%1
269
16th to endDay
24%34%28%9%2
270
May1st to 15thDay
10%17%33%27%8%1
384
16th to endDay
10%16%29%23%15%4
517
June1st to 15thDay
7%14%26%26%20%5%
495
16th to endDay
48%27%29%24%6%
495
July1st to 15thDay
11%421%26%28%7%
475
16th to endDay
14%215%29%29%8%
429
August1st to 15thDay
16%9%25%28%13%5%
315
16th to endDay
12%7%26%32%16%4
332
September1st to 15thDay
12%12%33%24%13%4
315
16th to endDay
9%15%33%24%11%5%
192
October1st to 15thDay
415%28%28%17%5%
135
16th to endDay
9%11%31%25%18%3
144
November1st to 15thDay
5%14%30%27%17%5%
135
16th to endDay
322%42%25%5%
135
December1st to 15thDay
6%31%38%24%1
100
16th to endDay
322%39%29%32
96
January1st to 15thNight
219%37%29%11%
894
16th to endNight
114%41%32%7%1
768
February1st to 15thNight
213%47%32%3
704
16th to endNight
217%43%32%3
632
March1st to 15thNight
413%38%35%8%
720
16th to endNight
5%15%38%32%7%
692
April1st to 15thNight
6%18%34%33%6%
539
16th to endNight
11%14%33%30%9%
540
May1st to 15thNight
12%10%28%35%11%1
540
16th to endNight
9%8%28%34%17%1
563
June1st to 15thNight
6%324%44%18%2
540
16th to endNight
2219%43%29%2
540
July1st to 15thNight
7%110%37%38%4
510
16th to endNight
7%9%32%46%4
564
August1st to 15thNight
8%210%34%39%3
539
16th to endNight
8%19%38%36%4
573
September1st to 15thNight
8%213%41%26%6%
540
16th to endNight
6%324%40%23%2
541
October1st to 15thNight
46%30%39%16%2
720
16th to endNight
46%27%40%17%2
768
November1st to 15thNight
212%30%41%10%1
950
16th to endNight
213%33%39%9%
975
December1st to 15thNight
218%39%33%5%
920
16th to endNight
217%39%33%6%
960
Page generated at 2017-12-05 08:19:02. Version ac04

Copyright 2017 A. Danko


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