Sky Hound Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sky Hound 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
60%
24465
27%
74688
20%
24423
68%
24423
42%
39317

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%
757
23%
2457
19%
756
68%
756
36%
1352
January11th to 20thNight
57%
744
26%
2417
21%
744
66%
744
38%
1299
January21st to endNight
59%
792
25%
2574
21%
792
66%
792
33%
1483
February1st to 10thNight
54%
720
24%
2340
20%
720
63%
720
40%
1192
February11th to 20thNight
50%
700
24%
2273
17%
700
62%
700
36%
1231
February21st to endNight
47%
592
28%
1772
17%
592
60%
592
39%
959
March1st to 10thNight
52%
720
26%
1980
17%
720
61%
720
43%
1113
March11th to 20thNight
55%
720
26%
1980
18%
720
61%
720
43%
1134
March21st to endNight
48%
792
24%
2178
12%
792
57%
792
41%
1233
April1st to 10thNight
45%
640
24%
1900
13%
640
56%
640
39%
1028
April11th to 20thNight
45%
533
25%
1743
15%
533
57%
533
35%
932
April21st to endNight
50%
540
32%
1620
18%
540
62%
540
41%
849
May1st to 10thNight
48%
540
25%
1620
16%
540
56%
540
37%
917
May11th to 20thNight
63%
531
26%
1595
20%
531
67%
531
40%
859
May21st to endNight
53%
583
22%
1654
15%
582
59%
582
37%
932
June1st to 10thNight
64%
540
27%
1440
20%
540
71%
540
48%
785
June11th to 20thNight
57%
540
30%
1440
20%
540
65%
540
52%
741
June21st to endNight
70%
540
31%
1440
28%
540
74%
540
60%
706
July1st to 10thNight
72%
525
21%
1528
19%
525
76%
525
44%
823
July11th to 20thNight
75%
522
24%
1566
23%
522
78%
522
43%
823
July21st to endNight
77%
591
22%
1674
21%
558
77%
558
35%
954
August1st to 10thNight
72%
537
26%
1602
20%
534
74%
534
44%
835
August11th to 20thNight
78%
534
31%
1602
25%
534
80%
534
44%
827
August21st to endNight
77%
594
33%
1872
32%
594
79%
594
47%
923
September1st to 10thNight
72%
560
36%
1820
32%
560
80%
560
54%
812
September11th to 20thNight
72%
720
36%
1980
27%
720
78%
720
56%
990
September21st to endNight
71%
720
37%
1980
25%
720
78%
720
57%
982
October1st to 10thNight
63%
720
31%
2128
22%
720
71%
720
49%
1095
October11th to 20thNight
66%
720
37%
2160
25%
720
77%
720
54%
1025
October21st to endNight
64%
792
37%
2376
26%
792
74%
792
53%
1137
November1st to 10thNight
61%
740
34%
2309
25%
740
71%
740
50%
1115
November11th to 20thNight
61%
821
34%
2531
25%
821
71%
821
52%
1173
November21st to endNight
61%
950
29%
2660
21%
950
69%
950
47%
1413
December1st to 10thNight
58%
950
23%
2660
14%
950
64%
950
45%
1439
December11th to 20thNight
59%
948
19%
3142
13%
948
63%
948
30%
1837
December21st to endNight
51%
997
12%
4675
11%
993
58%
993
22%
2369

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
34245%35%5%6%8%56%
74662
Night
342443445%8%58%
75174
TransparencyDay
24%6%12%25%21%11%
74387
Night
23%6%13%27%21%10%
74970
SeeingDay
6%7%23%35%22%7%
14151
Night
5%422%42%23%4
24490

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
34246%5%6%5%5%10%51%
1708
11th to 20thDay
24345%35%5%7%8%56%
1665
21st to endDay
35%37%7%45%5%49%48%
1782
February1st to 10thDay
23245%26%5%7%9%57%
1620
11th to 20thDay
35%35%5%2446%9%55%
1575
21st to endDay
36%36%7%346%6%8%49%
1479
March1st to 10thDay
45%345%35%5%5%10%52%
1980
11th to 20thDay
36%36%435%5%7%11%48%
1980
21st to endDay
36%345%35%7%7%8%48%
2178
April1st to 10thDay
34244345%6%9%55%
2059
11th to 20thDay
46%25%6%36%6%5%8%51%
2161
21st to endDay
4425%5%36%5%6%8%53%
2340
May1st to 10thDay
5%325%5%45%6%7%9%49%
2340
11th to 20thDay
5%425%6%35%6%7%8%49%
2301
21st to endDay
4425%5%36%6%7%8%48%
2620
June1st to 10thDay
4313435%5%7%9%57%
2520
11th to 20thDay
43134245%5%7%62%
2520
21st to endDay
22134335%5%8%65%
2520
July1st to 10thDay
4314437%6%7%8%53%
2382
11th to 20thDay
43245%35%7%8%8%50%
2340
21st to endDay
4325%5%47%7%8%9%46%
2545
August1st to 10thDay
33246%45%6%7%9%51%
2328
11th to 20thDay
33134346%7%8%59%
2299
21st to endDay
33145%35%6%7%8%56%
2484
September1st to 10thDay
5%21232445%6%66%
2138
11th to 20thDay
32234245%5%5%65%
1980
21st to endDay
5%213322347%69%
1980
October1st to 10thDay
6%423324347%62%
1832
11th to 20thDay
331232325%8%70%
1800
21st to endDay
342232345%6%67%
1980
November1st to 10thDay
432432345%6%65%
1767
11th to 20thDay
2312323348%70%
1626
21st to endDay
3415%43436%7%60%
1520
December1st to 10thDay
23245%25%46%8%58%
1520
11th to 20thDay
34346%45%6%9%11%45%
1926
21st to endDay
36%25%7%35%5%6%9%48%
2867
January1st to 10thNight
45%2443445%9%55%
2457
11th to 20thNight
25%235%35%447%60%
2417
21st to endNight
36%26%6%4446%9%49%
2574
February1st to 10thNight
24244245%6%8%60%
2340
11th to 20thNight
35%25%5%3445%8%55%
2272
21st to endNight
26%245%35%45%6%56%
1772
March1st to 10thNight
36%35%4245%6%8%54%
1980
11th to 20thNight
46%35%4245%5%9%54%
1980
21st to endNight
46%3432445%8%56%
2178
April1st to 10thNight
35%244345%5%6%58%
1900
11th to 20thNight
5%5%25%4245%7%7%53%
1743
21st to endNight
6%4235%2445%8%58%
1620
May1st to 10thNight
5%5%246%35%5%6%9%51%
1620
11th to 20thNight
5%5%245%25%5%48%57%
1594
21st to endNight
7%3245%36%48%9%48%
1654
June1st to 10thNight
43243345%7%9%57%
1440
11th to 20thNight
6%313323446%66%
1440
21st to endNight
231332345%5%70%
1440
July1st to 10thNight
2315%5%35%6%7%8%54%
1573
11th to 20thNight
32135%46%7%7%8%54%
1620
21st to endNight
4225%6%5%7%5%6%8%49%
1773
August1st to 10thNight
44243345%7%9%55%
1611
11th to 20thNight
33135%35%46%9%57%
1602
21st to endNight
3313426%5%7%9%58%
1872
September1st to 10thNight
3313313447%68%
1820
11th to 20thNight
431332335%6%68%
1980
21st to endNight
3313223335%72%
1980
October1st to 10thNight
6%323323436%64%
2128
11th to 20thNight
3313223346%71%
2160
21st to endNight
3413222346%68%
2376
November1st to 10thNight
3313323448%66%
2309
11th to 20thNight
221232346%7%68%
2531
21st to endNight
35%2442345%6%63%
2660
December1st to 10thNight
36%3442245%7%62%
2660
11th to 20thNight
35%25%6%45%5%7%9%49%
3271
21st to endNight
36%26%5%35%5%7%9%49%
4827

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
28%8%24%27%11%1
1709
11th to 20thDay
26%8%20%29%16%2
1665
21st to endDay
33%8%20%25%12%2
1782
February1st to 10thDay
23%8%23%32%12%3
1620
11th to 20thDay
27%5%16%34%16%2
1584
21st to endDay
29%8%15%30%15%3
1479
March1st to 10thDay
26%7%15%34%15%3
1980
11th to 20thDay
29%7%14%31%15%4
1980
21st to endDay
30%7%13%31%15%4
2178
April1st to 10thDay
24%7%15%27%20%8%
2059
11th to 20thDay
29%7%10%26%23%5%
2164
21st to endDay
25%8%10%29%25%4
2340
May1st to 10thDay
28%6%10%24%26%6%
2340
11th to 20thDay
28%6%9%26%23%7%
2304
21st to endDay
28%7%11%24%24%6%
2620
June1st to 10thDay
21%6%8%20%32%13%
2520
11th to 20thDay
20%5%5%16%27%27%
2520
21st to endDay
16%4313%28%35%
2520
July1st to 10thDay
25%6%8%15%21%25%
2318
11th to 20thDay
25%7%9%16%18%25%
2271
21st to endDay
29%8%10%18%16%19%
2404
August1st to 10thDay
26%7%10%18%18%20%
2313
11th to 20thDay
20%7%10%16%25%23%
2299
21st to endDay
22%6%9%18%27%19%
2484
September1st to 10thDay
19%47%15%26%30%
2138
11th to 20thDay
18%6%7%21%26%21%
1980
21st to endDay
17%4423%37%16%
1980
October1st to 10thDay
23%5%7%27%27%10%
1832
11th to 20thDay
15%47%33%32%10%
1800
21st to endDay
18%414%36%23%4
1980
November1st to 10thDay
19%6%14%34%21%5%
1767
11th to 20thDay
15%418%41%20%2
1626
21st to endDay
24%416%34%20%3
1520
December1st to 10thDay
23%7%26%26%14%4
1520
11th to 20thDay
28%11%22%31%8%1
1924
21st to endDay
30%7%19%24%17%3
2867
January1st to 10thNight
27%8%22%32%10%1
2457
11th to 20thNight
26%6%20%32%14%1
2417
21st to endNight
31%7%19%26%14%2
2574
February1st to 10thNight
22%7%22%32%14%2
2340
11th to 20thNight
28%6%15%29%20%3
2273
21st to endNight
24%7%16%27%21%5%
1772
March1st to 10thNight
25%6%15%36%16%2
1980
11th to 20thNight
26%5%11%35%17%4
1980
21st to endNight
27%5%16%32%16%4
2178
April1st to 10thNight
25%5%12%27%21%10%
1900
11th to 20thNight
26%6%12%25%26%4
1743
21st to endNight
23%6%10%31%25%5%
1620
May1st to 10thNight
27%7%12%24%24%6%
1620
11th to 20thNight
25%6%11%25%26%7%
1595
21st to endNight
26%7%12%28%22%5%
1654
June1st to 10thNight
22%5%9%22%27%15%
1440
11th to 20thNight
19%45%17%24%31%
1440
21st to endNight
15%4312%26%40%
1440
July1st to 10thNight
24%6%7%16%22%26%
1528
11th to 20thNight
22%7%9%20%16%26%
1566
21st to endNight
28%8%10%18%16%19%
1674
August1st to 10thNight
23%6%12%21%19%20%
1602
11th to 20thNight
22%6%8%17%23%23%
1602
21st to endNight
20%6%9%18%25%23%
1872
September1st to 10thNight
16%47%15%26%31%
1820
11th to 20thNight
16%5%7%23%25%23%
1980
21st to endNight
17%4418%38%19%
1980
October1st to 10thNight
21%5%8%28%26%13%
2128
11th to 20thNight
16%46%27%35%11%
2160
21st to endNight
18%412%34%27%5%
2376
November1st to 10thNight
17%6%12%35%24%5%
2309
11th to 20thNight
16%5%13%42%21%3
2531
21st to endNight
23%413%35%22%3
2660
December1st to 10thNight
23%6%23%31%16%3
2660
11th to 20thNight
29%10%21%29%10%1
3272
21st to endNight
29%8%18%25%16%3
4827

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
8%6%22%35%21%8%
270
11th to 20thDay
8%419%47%20%2
255
21st to endDay
4217%50%22%5%
264
February1st to 10thDay
39%34%41%11%3
240
11th to 20thDay
5%5%32%37%18%3
240
21st to endDay
5%14%33%38%8%1
328
March1st to 10thDay
8%13%29%37%12%1
420
11th to 20thDay
10%11%25%36%15%3
420
21st to endDay
8%12%32%33%14%1
462
April1st to 10thDay
8%19%26%28%15%4
420
11th to 20thDay
13%17%33%24%11%3
412
21st to endDay
9%17%24%28%17%5%
420
May1st to 10thDay
7%12%29%32%16%4
423
11th to 20thDay
7%10%28%25%21%8%
448
21st to endDay
6%11%21%28%25%9%
575
June1st to 10thDay
6%5%20%32%26%10%
630
11th to 20thDay
5%8%26%33%23%5%
630
21st to endDay
3423%37%25%7%
630
July1st to 10thDay
3316%34%32%13%
488
11th to 20thDay
4318%35%30%10%
444
21st to endDay
3210%33%35%16%
487
August1st to 10thDay
3319%36%28%11%
447
11th to 20thDay
5%315%35%27%15%
437
21st to endDay
3219%33%32%11%
495
September1st to 10thDay
5%419%31%27%14%
450
11th to 20thDay
5%6%20%38%22%9%
450
21st to endDay
7%6%18%30%30%9%
450
October1st to 10thDay
8%8%20%30%21%15%
302
11th to 20thDay
5%9%20%34%23%9%
270
21st to endDay
6%6%25%37%23%3
297
November1st to 10thDay
7%9%24%35%23%3
270
11th to 20thDay
46%22%41%19%7%
270
21st to endDay
7%421%38%23%7%
270
December1st to 10thDay
45%22%43%20%5%
270
11th to 20thDay
7%319%49%19%3
270
21st to endDay
9%421%45%17%4
297
January1st to 10thNight
5%320%42%24%5%
760
11th to 20thNight
4323%44%20%6%
744
21st to endNight
5%220%50%18%5%
792
February1st to 10thNight
45%28%45%15%3
720
11th to 20thNight
45%29%45%14%4
704
21st to endNight
5%6%33%42%13%1
592
March1st to 10thNight
7%5%28%42%14%3
720
11th to 20thNight
6%426%43%19%3
720
21st to endNight
7%6%32%43%11%1
792
April1st to 10thNight
6%8%34%38%11%2
640
11th to 20thNight
9%8%32%38%12%1
533
21st to endNight
6%6%30%39%16%3
540
May1st to 10thNight
5%6%33%38%14%3
540
11th to 20thNight
8%318%41%27%3
531
21st to endNight
7%6%25%36%23%4
584
June1st to 10thNight
45%19%43%27%2
540
11th to 20thNight
7%5%26%42%18%2
540
21st to endNight
3219%46%27%3
540
July1st to 10thNight
3112%40%38%6%
525
11th to 20thNight
4210%44%38%3
522
21st to endNight
42437%46%7%
591
August1st to 10thNight
4110%42%37%4
537
11th to 20thNight
417%47%36%4
534
21st to endNight
3112%41%37%6%
594
September1st to 10thNight
4215%38%35%6%
560
11th to 20thNight
4215%42%28%10%
720
21st to endNight
4318%35%29%12%
720
October1st to 10thNight
6%320%42%24%5%
720
11th to 20thNight
3421%42%24%6%
720
21st to endNight
5%322%39%26%5%
792
November1st to 10thNight
4224%38%24%6%
740
11th to 20thNight
3426%44%17%6%
821
21st to endNight
45%21%41%24%5%
950
December1st to 10thNight
6%323%48%18%2
950
11th to 20thNight
6%420%51%17%3
950
21st to endNight
9%5%22%47%15%2
1012
Page generated at 2024-01-13 07:37:56. Version ac07

Copyright 2024 Attilla Danko


Sky Hound Observatory Clear Sky Chart |Charts Home