Sigoglin Hills Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sigoglin Hills Observatory clear sky chart from 2005-11-05 to 2017-09-17.

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
45%
15409
21%
46687
15%
15365
51%
15365
26%
30050

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
19%
720
15%
2327
8%
716
28%
716
14%
1718
January16th to endNight
23%
768
18%
2496
9%
768
33%
768
16%
1749
February1st to 15thNight
23%
704
14%
2151
7%
701
31%
701
18%
1535
February16th to endNight
20%
631
15%
1893
6%
631
28%
631
16%
1373
March1st to 15thNight
26%
720
18%
2086
10%
720
32%
720
18%
1455
March16th to endNight
36%
768
15%
2112
9%
768
41%
768
24%
1447
April1st to 15thNight
39%
584
22%
1842
14%
584
49%
584
28%
1127
April16th to endNight
44%
540
23%
1653
13%
540
53%
540
27%
1060
May1st to 15thNight
43%
540
15%
1620
10%
540
48%
540
21%
1136
May16th to endNight
63%
562
19%
1684
15%
561
66%
561
31%
1021
June1st to 15thNight
69%
540
20%
1620
18%
540
72%
540
40%
916
June16th to endNight
71%
540
20%
1472
16%
540
73%
540
39%
870
July1st to 15thNight
62%
510
16%
1432
14%
510
63%
510
31%
918
July16th to endNight
75%
564
22%
1595
19%
531
77%
531
39%
889
August1st to 15thNight
75%
539
24%
1609
22%
536
76%
536
41%
899
August16th to endNight
79%
573
26%
1851
27%
573
80%
573
40%
971
September1st to 15thNight
67%
669
26%
1929
23%
669
69%
669
36%
1138
September16th to endNight
60%
665
29%
1837
23%
665
63%
665
35%
1112
October1st to 15thNight
56%
660
33%
1848
27%
660
62%
660
39%
1080
October16th to endNight
43%
704
26%
2178
20%
704
52%
704
28%
1347
November1st to 15thNight
48%
700
29%
2276
24%
700
58%
700
33%
1291
November16th to endNight
35%
720
22%
2340
16%
720
43%
720
23%
1511
December1st to 15thNight
30%
720
14%
2340
9%
720
35%
720
16%
1671
December16th to endNight
22%
768
17%
2496
8%
768
33%
768
14%
1816

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
14%6%35%5%35%45%7%37%
48063
Night
14%6%25%5%3445%7%40%
46876
Cloud CoverDay
14%6%35%5%3445%7%37%
48073
Night
14%6%35%43445%7%40%
46880
TransparencyDay
45%310%22%14%2
47771
Night
43%310%23%16%3
46687
SeeingDay
16%5%19%24%21%13%
5505
Night
17%6%22%30%19%2
15410

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 15thDay
19%10%5%8%6%33445%29%
1611
16th to endDay
17%9%5%8%6%34345%31%
1728
February1st to 15thDay
15%10%49%6%33345%31%
1709
16th to endDay
16%10%5%7%5%45%45%6%29%
1580
March1st to 15thDay
22%8%36%423435%33%
1861
16th to endDay
18%8%26%6%45%446%33%
2112
April1st to 15thDay
15%8%25%5%24446%39%
2115
16th to endDay
15%6%245%25%5%5%6%38%
2304
May1st to 15thDay
20%6%35%5%3446%7%32%
2331
16th to endDay
10%425%6%36%6%6%8%37%
2431
June1st to 15thDay
10%325%5%35%5%6%9%42%
2340
16th to endDay
8%435%5%36%6%7%9%39%
2481
July1st to 15thDay
14%5%25%5%35%6%6%8%34%
2436
16th to endDay
9%435%6%47%6%7%10%35%
2465
August1st to 15thDay
8%5%26%6%246%7%9%40%
2340
16th to endDay
7%5%25%5%36%6%7%9%40%
2348
September1st to 15thDay
14%5%246%45%5%5%6%40%
2018
16th to endDay
14%425%433346%46%
1829
October1st to 15thDay
11%5%135%2435%6%50%
1782
16th to endDay
19%6%14422435%45%
1692
November1st to 15thDay
12%434324335%50%
1582
16th to endDay
17%9%35%43335%440%
1620
December1st to 15thDay
23%11%36%424435%29%
1620
16th to endDay
19%13%37%5%33346%29%
1728
January1st to 15thNight
17%10%49%7%35%34427%
2327
16th to endNight
18%10%47%5%34345%32%
2496
February1st to 15thNight
19%9%46%5%34445%32%
2149
16th to endNight
16%12%47%6%25%345%29%
1893
March1st to 15thNight
17%8%37%5%2434436%
2074
16th to endNight
17%7%35%5%3445%7%35%
2112
April1st to 15thNight
13%5%25%43445%6%44%
1842
16th to endNight
14%6%25%5%25%45%6%41%
1653
May1st to 15thNight
16%5%36%5%46%46%7%31%
1620
16th to endNight
8%325%5%45%6%7%10%40%
1682
June1st to 15thNight
6%313425%6%5%11%49%
1620
16th to endNight
5%314435%5%7%10%47%
1472
July1st to 15thNight
10%6%245%3445%8%43%
1518
16th to endNight
6%313435%5%7%11%47%
1703
August1st to 15thNight
6%2135%3347%10%50%
1620
16th to endNight
5%22342447%9%52%
1851
September1st to 15thNight
12%42342345%9%46%
1929
16th to endNight
12%5%25%323346%50%
1837
October1st to 15thNight
9%424414447%52%
1848
16th to endNight
15%6%25%424346%45%
2178
November1st to 15thNight
13%5%14423346%51%
2276
16th to endNight
18%8%35%42325%5%40%
2340
December1st to 15thNight
21%10%46%5%24345%30%
2340
16th to endNight
21%12%37%5%34346%27%
2496

Percentage Cloud Cover SE (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
19%10%5%8%6%33345%28%
1611
16th to endDay
17%9%5%8%5%34335%31%
1728
February1st to 15thDay
15%10%49%7%24345%30%
1709
16th to endDay
16%10%38%445%5%5%5%29%
1580
March1st to 15thDay
23%8%35%433435%33%
1872
16th to endDay
18%7%36%6%34446%33%
2111
April1st to 15thDay
16%7%25%5%33446%39%
2115
16th to endDay
15%6%245%345%5%7%38%
2304
May1st to 15thDay
21%6%35%5%3446%7%32%
2331
16th to endDay
10%435%6%35%6%6%9%38%
2431
June1st to 15thDay
10%325%5%35%5%6%9%42%
2340
16th to endDay
8%425%5%36%6%7%9%39%
2481
July1st to 15thDay
14%6%25%5%36%6%6%8%34%
2436
16th to endDay
9%425%6%46%6%7%9%36%
2465
August1st to 15thDay
8%5%25%6%35%5%8%9%39%
2340
16th to endDay
8%5%25%6%45%6%6%9%40%
2348
September1st to 15thDay
14%4246%345%5%6%40%
2018
16th to endDay
14%5%245%2335%6%46%
1829
October1st to 15thDay
11%5%1442435%6%50%
1782
16th to endDay
20%5%14412345%45%
1692
November1st to 15thDay
12%435%323335%51%
1582
16th to endDay
17%9%35%42335%5%39%
1620
December1st to 15thDay
23%11%36%424435%29%
1620
16th to endDay
19%13%36%5%34346%29%
1728
January1st to 15thNight
17%10%5%9%7%34445%27%
2327
16th to endNight
18%10%46%43434432%
2496
February1st to 15thNight
19%8%5%7%434435%32%
2142
16th to endNight
16%12%47%6%35%346%29%
1893
March1st to 15thNight
17%8%36%5%34335%35%
2086
16th to endNight
17%6%25%5%2446%6%36%
2112
April1st to 15thNight
13%435%43446%7%43%
1842
16th to endNight
14%7%25%435%45%6%41%
1653
May1st to 15thNight
16%5%35%6%46%5%6%7%31%
1619
16th to endNight
8%3145%45%6%7%10%41%
1682
June1st to 15thNight
6%223425%5%5%11%49%
1620
16th to endNight
5%313435%5%7%10%47%
1472
July1st to 15thNight
10%6%25%5%335%5%8%43%
1518
16th to endNight
6%313435%5%7%10%48%
1703
August1st to 15thNight
5%3135%245%6%10%50%
1620
16th to endNight
5%3243245%7%9%52%
1851
September1st to 15thNight
12%41342435%9%48%
1929
16th to endNight
12%5%24423346%50%
1837
October1st to 15thNight
9%4243245%5%7%52%
1848
16th to endNight
15%5%15%433346%45%
2178
November1st to 15thNight
13%423413346%51%
2276
16th to endNight
18%8%35%423346%39%
2340
December1st to 15thNight
22%10%46%42444430%
2340
16th to endNight
21%12%37%5%34346%27%
2496

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
58%27%19%11%
1612
16th to endDay
55%19%24%7%1
1728
February1st to 15thDay
56%28%22%9%1
1711
16th to endDay
55%210%22%9%
1580
March1st to 15thDay
54%210%19%12%1
1872
16th to endDay
52%311%22%9%
2112
April1st to 15thDay
45%29%26%13%2
2115
16th to endDay
44%310%23%13%4
2304
May1st to 15thDay
50%313%19%12%1
2331
16th to endDay
41%5%14%24%12%1
2435
June1st to 15thDay
37%314%25%17%1
2340
16th to endDay
38%5%12%21%19%2
2481
July1st to 15thDay
44%412%17%16%3
2294
16th to endDay
41%415%24%12%2
2310
August1st to 15thDay
37%5%13%25%16%1
2327
16th to endDay
37%411%24%16%4
2348
September1st to 15thDay
43%39%18%19%5%
2018
16th to endDay
38%26%25%23%2
1829
October1st to 15thDay
34%37%28%21%3
1782
16th to endDay
42%29%26%16%2
1692
November1st to 15thDay
37%26%24%21%6%
1582
16th to endDay
47%17%23%18%1
1620
December1st to 15thDay
58%19%18%9%1
1620
16th to endDay
56%210%20%8%
1728
January1st to 15thNight
59%27%15%12%1
2327
16th to endNight
55%18%23%9%1
2496
February1st to 15thNight
54%29%22%9%1
2151
16th to endNight
56%210%20%9%
1893
March1st to 15thNight
51%28%21%13%2
2086
16th to endNight
47%313%23%10%1
2112
April1st to 15thNight
39%39%22%21%3
1842
16th to endNight
43%38%23%14%6%
1653
May1st to 15thNight
49%5%11%21%9%2
1620
16th to endNight
36%416%22%15%3
1684
June1st to 15thNight
28%414%29%17%4
1620
16th to endNight
29%6%18%23%18%4
1472
July1st to 15thNight
39%412%22%15%5%
1432
16th to endNight
27%6%16%28%18%2
1595
August1st to 15thNight
27%416%26%20%3
1609
16th to endNight
26%413%28%21%4
1851
September1st to 15thNight
33%312%22%20%6%
1929
16th to endNight
35%36%24%27%3
1837
October1st to 15thNight
31%37%29%22%5%
1848
16th to endNight
41%27%26%19%3
2178
November1st to 15thNight
34%26%23%26%6%
2276
16th to endNight
47%17%24%16%1
2340
December1st to 15thNight
56%210%19%9%1
2340
16th to endNight
58%29%19%9%1
2496

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
30%7%43%8%7%2
90
16th to endDay
25%18%45%8%2
96
February1st to 15thDay
13%17%45%18%4
90
16th to endDay
24%9%32%23%9%
81
March1st to 15thDay
28%9%35%21%3
162
16th to endDay
19%11%30%25%12%
288
April1st to 15thDay
20%11%24%25%13%4
270
16th to endDay
20%6%22%25%15%10%
270
May1st to 15thDay
22%7%22%24%15%7%
288
16th to endDay
16%119%25%20%16%
331
June1st to 15thDay
10%112%25%33%16%
315
16th to endDay
9%417%30%25%12%
456
July1st to 15thDay
20%112%26%20%18%
398
16th to endDay
9%18%19%28%32%
326
August1st to 15thDay
13%5%19%32%28%
313
16th to endDay
11%6%24%32%24%
332
September1st to 15thDay
17%18%22%27%22%
315
16th to endDay
16%112%20%31%16%
259
October1st to 15thDay
12%319%29%23%10%
255
16th to endDay
18%326%29%19%2
204
November1st to 15thDay
16%324%23%20%12%
90
16th to endDay
22%8%32%24%11%1
90
December1st to 15thDay
23%11%30%27%5%2
90
16th to endDay
21%13%48%12%3
96
January1st to 15thNight
24%12%36%20%5%
720
16th to endNight
26%11%31%27%3
768
February1st to 15thNight
25%9%34%28%1
704
16th to endNight
24%11%36%26%2
631
March1st to 15thNight
22%13%29%26%7%
720
16th to endNight
19%7%28%30%12%
768
April1st to 15thNight
15%9%30%32%11%
584
16th to endNight
16%5%28%33%14%2
540
May1st to 15thNight
19%323%35%15%3
540
16th to endNight
9%215%38%28%6%
563
June1st to 15thNight
7%12%39%35%3
540
16th to endNight
7%11%44%32%3
540
July1st to 15thNight
14%19%34%33%5%
510
16th to endNight
7%17%32%42%8%
564
August1st to 15thNight
7%5%33%46%7%
539
16th to endNight
5%5%35%44%8%
573
September1st to 15thNight
14%18%27%41%7%
669
16th to endNight
15%212%30%33%6%
665
October1st to 15thNight
10%421%31%25%6%
660
16th to endNight
19%6%25%31%15%1
704
November1st to 15thNight
16%6%24%29%20%2
700
16th to endNight
23%8%27%28%10%
720
December1st to 15thNight
28%8%26%27%8%1
720
16th to endNight
29%10%31%24%4
768
Page generated at 2017-09-18 08:38:21. Version ac04

Copyright 2017 A. Danko


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