Hidden Loft Observatory
Clear Sky Chart
History

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

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%
23954
35%
74308
29%
23905
76%
23905
50%
35932

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
61%
758
32%
2457
28%
756
70%
756
45%
1203
January11th to 20thNight
65%
724
35%
2352
31%
724
74%
724
48%
1114
January21st to endNight
58%
792
34%
2574
30%
792
69%
792
39%
1342
February1st to 10thNight
64%
720
36%
2303
33%
720
74%
720
49%
1097
February11th to 20thNight
55%
700
32%
2099
25%
700
66%
700
43%
1108
February21st to endNight
52%
592
37%
1689
28%
592
63%
592
47%
876
March1st to 10thNight
54%
720
36%
1980
24%
720
65%
720
48%
1037
March11th to 20thNight
64%
720
37%
1980
27%
720
73%
720
55%
991
March21st to endNight
63%
792
37%
2178
24%
792
73%
792
55%
1086
April1st to 10thNight
66%
720
37%
1980
25%
720
76%
720
63%
919
April11th to 20thNight
59%
569
41%
1813
30%
569
72%
569
60%
754
April21st to endNight
69%
540
46%
1771
37%
540
81%
540
70%
665
May1st to 10thNight
69%
540
42%
1620
31%
540
79%
540
68%
661
May11th to 20thNight
72%
531
41%
1594
33%
531
78%
531
68%
666
May21st to endNight
74%
582
43%
1746
35%
582
80%
582
79%
659
June1st to 10thNight
79%
540
36%
1620
30%
540
81%
540
65%
694
June11th to 20thNight
83%
540
39%
1620
33%
540
85%
540
77%
632
June21st to endNight
79%
540
29%
1620
25%
540
80%
540
56%
761
July1st to 10thNight
79%
525
23%
1575
20%
525
80%
525
43%
839
July11th to 20thNight
80%
522
18%
1566
15%
522
80%
522
34%
931
July21st to endNight
75%
591
15%
1674
14%
558
74%
558
27%
1083
August1st to 10thNight
85%
537
24%
1602
23%
534
85%
534
43%
870
August11th to 20thNight
80%
534
27%
1602
27%
534
80%
534
38%
903
August21st to endNight
83%
627
30%
2008
31%
627
83%
627
40%
1066
September1st to 10thNight
76%
720
30%
1980
26%
720
77%
720
42%
1141
September11th to 20thNight
83%
720
40%
1980
34%
720
85%
720
59%
970
September21st to endNight
78%
720
38%
1980
28%
720
83%
720
59%
975
October1st to 10thNight
74%
720
37%
2056
28%
720
80%
720
60%
972
October11th to 20thNight
78%
720
42%
2160
34%
720
84%
720
69%
899
October21st to endNight
77%
792
45%
2376
37%
792
83%
792
68%
996
November1st to 10thNight
73%
740
43%
2220
36%
740
80%
740
64%
968
November11th to 20thNight
73%
760
42%
2308
35%
760
79%
760
60%
1034
November21st to endNight
60%
760
36%
2470
32%
760
68%
760
45%
1218
December1st to 10thNight
63%
760
36%
2470
34%
760
70%
760
47%
1189
December11th to 20thNight
56%
760
31%
2942
30%
758
66%
758
32%
1600
December21st to endNight
58%
826
22%
4343
31%
817
65%
817
26%
2013

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
5%31332445%6%64%
74947
Night
5%313323446%64%
74791
TransparencyDay
20%46%12%24%34%
74674
Night
20%46%12%25%33%
74586
SeeingDay
7%9%25%34%21%5%
13764
Night
6%316%39%31%5%
23972

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
7%5%24423446%60%
1708
11th to 20thDay
6%4134235%36%63%
1620
21st to endDay
7%5%23323346%62%
1782
February1st to 10thDay
6%423323346%66%
1655
11th to 20thDay
9%5%35%42434358%
1750
21st to endDay
8%6%23323236%62%
1565
March1st to 10thDay
6%5%24424346%60%
1980
11th to 20thDay
6%424323336%64%
1980
21st to endDay
4312324335%70%
2178
April1st to 10thDay
321222345%5%71%
1980
11th to 20thDay
331221223478%
2092
21st to endDay
2212212335%77%
2185
May1st to 10thDay
221222323477%
2340
11th to 20thDay
121222333476%
2301
21st to endDay
211121212385%
2530
June1st to 10thDay
3212212346%75%
2340
11th to 20thDay
111211222384%
2340
21st to endDay
221432445%6%66%
2340
July1st to 10thDay
42246%45%6%7%8%52%
2340
11th to 20thDay
5%5%25%6%48%8%8%11%38%
2340
21st to endDay
9%5%36%7%5%7%8%9%12%29%
2545
August1st to 10thDay
6%43445%6%6%8%9%46%
2328
11th to 20thDay
4325%5%46%8%8%10%44%
2299
21st to endDay
33246%46%6%7%8%50%
2343
September1st to 10thDay
6%425%435%5%7%7%53%
1980
11th to 20thDay
3213423345%70%
1980
21st to endDay
321331444470%
1980
October1st to 10thDay
321232335%6%70%
1904
11th to 20thDay
221221233480%
1800
21st to endDay
221332234475%
1980
November1st to 10thDay
221221345%7%73%
1859
11th to 20thDay
331332344470%
1868
21st to endDay
7%5%24423446%61%
1710
December1st to 10thDay
8%4135%24446%59%
1710
11th to 20thDay
9%8%36%42346%6%50%
2169
21st to endDay
8%6%25%423345%57%
3146
January1st to 10thNight
7%424423447%59%
2457
11th to 20thNight
7%424323336%65%
2352
21st to endNight
8%6%23434445%59%
2574
February1st to 10thNight
6%423324245%66%
2303
11th to 20thNight
7%6%24324436%58%
2098
21st to endNight
7%6%2422334463%
1689
March1st to 10thNight
5%423424446%61%
1980
11th to 20thNight
7%313322335%68%
1980
21st to endNight
5%322423346%66%
2178
April1st to 10thNight
3213222446%71%
1980
11th to 20thNight
221331332476%
1813
21st to endNight
221111123481%
1771
May1st to 10thNight
122213346%76%
1620
11th to 20thNight
2212221337%76%
1594
21st to endNight
21111122386%
1746
June1st to 10thNight
2212222337%73%
1620
11th to 20thNight
111211213483%
1620
21st to endNight
2323424345%69%
1620
July1st to 10thNight
43146%35%6%6%10%52%
1620
11th to 20thNight
3425%5%47%8%9%14%39%
1620
21st to endNight
45%27%7%5%7%9%10%14%31%
1773
August1st to 10thNight
32234347%8%12%52%
1611
11th to 20thNight
44245%46%5%6%10%48%
1602
21st to endNight
3324446%6%8%10%50%
2008
September1st to 10thNight
6%5%2443446%7%54%
1980
11th to 20thNight
231333333473%
1980
21st to endNight
221332434470%
1980
October1st to 10thNight
3213323445%70%
2056
11th to 20thNight
211221334478%
2160
21st to endNight
321221222480%
2376
November1st to 10thNight
3213213346%72%
2220
11th to 20thNight
3213313345%72%
2308
21st to endNight
7%424323445%61%
2470
December1st to 10thNight
8%41322345%6%62%
2470
11th to 20thNight
8%6%37%5%24445%53%
3041
21st to endNight
8%6%243345%4456%
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
25%35%14%28%25%
1709
11th to 20thDay
22%45%9%29%31%
1620
21st to endDay
25%25%15%26%28%
1782
February1st to 10thDay
21%25%12%22%39%
1655
11th to 20thDay
29%36%12%22%29%
1760
21st to endDay
24%1310%28%33%
1565
March1st to 10thDay
24%25%9%30%31%
1980
11th to 20thDay
21%348%27%37%
1980
21st to endDay
17%3311%34%32%
2178
April1st to 10thDay
14%128%35%39%
1980
11th to 20thDay
11%226%26%52%
2095
21st to endDay
11%238%27%49%
2185
May1st to 10thDay
12%137%22%55%
2340
11th to 20thDay
12%249%22%51%
2304
21st to endDay
7%125%24%61%
2530
June1st to 10thDay
11%136%24%55%
2340
11th to 20thDay
8%12417%69%
2340
21st to endDay
17%45%9%18%47%
2340
July1st to 10thDay
25%8%11%15%15%27%
2276
11th to 20thDay
33%11%18%20%12%6%
2271
21st to endDay
39%12%18%18%9%3
2404
August1st to 10thDay
30%9%12%14%19%16%
2313
11th to 20thDay
28%9%15%17%19%11%
2299
21st to endDay
27%8%13%19%20%14%
2343
September1st to 10thDay
28%5%9%19%18%21%
1980
11th to 20thDay
16%46%12%26%35%
1980
21st to endDay
17%46%9%29%35%
1980
October1st to 10thDay
13%46%14%26%37%
1904
11th to 20thDay
10%249%25%51%
1800
21st to endDay
13%249%26%46%
1980
November1st to 10thDay
11%2412%36%35%
1859
11th to 20thDay
16%3410%28%40%
1868
21st to endDay
22%45%11%24%34%
1710
December1st to 10thDay
23%46%14%27%26%
1710
11th to 20thDay
31%46%16%23%20%
2168
21st to endDay
26%5%6%14%31%19%
3146
January1st to 10thNight
23%35%13%32%23%
2457
11th to 20thNight
22%25%12%28%32%
2352
21st to endNight
28%35%12%29%23%
2574
February1st to 10thNight
21%2412%22%38%
2303
11th to 20thNight
26%35%13%24%28%
2099
21st to endNight
23%3311%28%32%
1689
March1st to 10thNight
23%25%11%26%33%
1980
11th to 20thNight
19%2411%24%40%
1980
21st to endNight
19%2413%33%29%
2178
April1st to 10thNight
14%1310%34%37%
1980
11th to 20thNight
13%238%27%47%
1813
21st to endNight
9%129%29%50%
1771
May1st to 10thNight
10%249%25%51%
1620
11th to 20thNight
10%3410%22%51%
1595
21st to endNight
6%126%25%61%
1746
June1st to 10thNight
12%236%22%55%
1620
11th to 20thNight
7%12415%70%
1620
21st to endNight
16%5%5%6%16%52%
1620
July1st to 10thNight
23%7%12%14%14%30%
1575
11th to 20thNight
27%12%20%21%13%7%
1566
21st to endNight
34%13%24%16%9%4
1674
August1st to 10thNight
21%10%14%21%16%18%
1602
11th to 20thNight
27%7%17%17%18%13%
1602
21st to endNight
24%8%14%21%20%14%
2008
September1st to 10thNight
27%6%9%21%17%21%
1980
11th to 20thNight
15%5%5%13%27%35%
1980
21st to endNight
17%35%12%30%34%
1980
October1st to 10thNight
14%47%13%23%38%
2056
11th to 20thNight
10%3410%25%49%
2160
21st to endNight
11%2310%26%48%
2376
November1st to 10thNight
14%2412%33%37%
2220
11th to 20thNight
15%2312%28%39%
2308
21st to endNight
24%2412%26%31%
2470
December1st to 10thNight
22%36%15%25%28%
2470
11th to 20thNight
31%46%14%24%21%
3041
21st to endNight
27%6%6%12%28%21%
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
14%9%26%40%12%
270
11th to 20thDay
13%5%27%37%15%3
240
21st to endDay
8%9%30%34%16%2
264
February1st to 10thDay
7%9%32%32%16%5%
275
11th to 20thDay
16%18%32%28%5%
415
21st to endDay
14%19%38%23%6%1
346
March1st to 10thDay
12%17%34%28%8%1
420
11th to 20thDay
9%19%28%29%13%2
420
21st to endDay
8%25%33%24%10%1
462
April1st to 10thDay
6%17%34%25%15%3
420
11th to 20thDay
6%18%38%25%10%3
412
21st to endDay
5%19%32%29%12%4
420
May1st to 10thDay
5%15%36%26%14%4
423
11th to 20thDay
39%35%35%16%3
448
21st to endDay
310%37%35%13%2
485
June1st to 10thDay
46%32%36%18%4
450
11th to 20thDay
27%28%40%21%4
450
21st to endDay
4321%45%23%5%
450
July1st to 10thDay
3111%42%37%6%
446
11th to 20thDay
5%17%36%38%13%
444
21st to endDay
7%25%30%42%14%
487
August1st to 10thDay
5%16%38%40%11%
447
11th to 20thDay
5%18%35%39%13%
437
21st to endDay
318%31%41%16%
495
September1st to 10thDay
8%215%40%27%8%
450
11th to 20thDay
4117%45%25%8%
450
21st to endDay
6%6%23%35%21%8%
450
October1st to 10thDay
38%28%32%23%7%
374
11th to 20thDay
35%23%38%28%3
270
21st to endDay
36%22%37%25%7%
297
November1st to 10thDay
6%8%26%40%19%2
270
11th to 20thDay
5%5%24%40%23%2
270
21st to endDay
9%13%26%35%16%1
270
December1st to 10thDay
10%6%28%35%19%2
270
11th to 20thDay
12%8%33%34%12%1
270
21st to endDay
14%12%29%30%12%2
297
January1st to 10thNight
8%321%42%22%4
760
11th to 20thNight
9%318%42%24%4
724
21st to endNight
13%320%42%18%4
792
February1st to 10thNight
8%320%39%24%6%
720
11th to 20thNight
10%424%42%17%2
704
21st to endNight
11%6%25%40%16%2
592
March1st to 10thNight
8%6%28%41%15%2
720
11th to 20thNight
8%5%18%37%26%6%
720
21st to endNight
5%422%42%24%3
792
April1st to 10thNight
35%21%48%22%2
720
11th to 20thNight
46%27%41%22%1
569
21st to endNight
35%22%45%23%3
540
May1st to 10thNight
25%22%46%23%2
540
11th to 20thNight
2221%47%25%3
531
21st to endNight
2319%46%28%2
584
June1st to 10thNight
2212%48%34%3
540
11th to 20thNight
2111%49%34%3
540
21st to endNight
1210%38%45%4
540
July1st to 10thNight
216%33%52%6%
525
11th to 20thNight
3323%62%8%
522
21st to endNight
5%1321%57%13%
591
August1st to 10thNight
4220%60%15%
537
11th to 20thNight
41422%59%10%
534
21st to endNight
41321%58%14%
627
September1st to 10thNight
7%15%30%45%11%
720
11th to 20thNight
317%38%44%8%
720
21st to endNight
3212%41%35%8%
720
October1st to 10thNight
3215%45%31%4
720
11th to 20thNight
3214%43%32%6%
720
21st to endNight
3213%40%31%10%
792
November1st to 10thNight
4117%43%28%6%
740
11th to 20thNight
3216%45%31%3
760
21st to endNight
9%421%39%22%5%
760
December1st to 10thNight
11%218%41%24%3
760
11th to 20thNight
10%421%41%19%4
760
21st to endNight
11%5%19%41%20%4
836
Page generated at 2024-01-08 09:14:21. Version ac07

Copyright 2024 Attilla Danko


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