Bones' Landing Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bones' Landing Observatory clear sky chart from 2005-11-05 to 2017-12-02.

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
36%
15592
18%
47874
10%
15553
45%
15553
21%
31313

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
15%
716
17%
2327
5%
716
30%
716
11%
1586
January16th to endNight
12%
768
15%
2496
3%
768
27%
768
13%
1706
February1st to 15thNight
14%
704
16%
2287
4%
701
28%
701
13%
1490
February16th to endNight
16%
631
17%
1928
4%
631
30%
631
12%
1356
March1st to 15thNight
21%
720
18%
1980
7%
720
32%
720
18%
1358
March16th to endNight
22%
768
16%
2112
8%
768
29%
768
18%
1467
April1st to 15thNight
24%
718
16%
1829
5%
718
31%
718
21%
1277
April16th to endNight
38%
658
17%
1738
8%
658
42%
658
24%
1186
May1st to 15thNight
38%
540
15%
1620
8%
540
45%
540
20%
1125
May16th to endNight
51%
459
16%
1582
14%
459
55%
459
23%
1005
June1st to 15thNight
53%
360
18%
1440
18%
360
61%
360
24%
846
June16th to endNight
55%
360
17%
1440
16%
360
63%
360
25%
829
July1st to 15thNight
57%
439
11%
1459
10%
439
59%
439
23%
939
July16th to endNight
67%
564
16%
1595
13%
531
69%
531
35%
933
August1st to 15thNight
66%
539
18%
1609
14%
536
67%
536
31%
1010
August16th to endNight
67%
687
22%
1833
15%
687
68%
687
37%
1127
September1st to 15thNight
56%
720
23%
1812
13%
720
61%
720
34%
1178
September16th to endNight
54%
717
23%
2007
18%
717
58%
717
30%
1280
October1st to 15thNight
44%
720
22%
2160
18%
720
53%
720
26%
1369
October16th to endNight
33%
768
25%
2304
14%
768
48%
768
25%
1417
November1st to 15thNight
39%
760
23%
2355
15%
760
50%
760
24%
1477
November16th to endNight
28%
780
18%
2730
11%
780
40%
780
16%
1750
December1st to 15thNight
26%
728
13%
2546
7%
728
35%
728
12%
1751
December16th to endNight
17%
768
16%
2685
4%
768
32%
768
12%
1851

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
12%6%36%5%35%5%6%7%37%
48556
Night
11%5%245%35%5%5%7%42%
48066
Cloud CoverDay
11%6%36%6%35%5%6%7%38%
48566
Night
11%5%25%5%35%5%5%7%42%
48070
TransparencyDay
43%9%13%19%12%1
48266
Night
39%8%14%21%13%1
47874
SeeingDay
19%13%24%21%15%6%
5814
Night
18%14%25%26%12%1
15598

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
11%6%37%7%5%6%5%5%6%35%
1611
16th to endDay
10%8%48%7%35%45%6%36%
1728
February1st to 15thDay
10%10%47%5%4445%6%35%
1575
16th to endDay
7%9%310%7%34447%38%
1541
March1st to 15thDay
12%7%47%6%3435%5%39%
1969
16th to endDay
13%7%36%6%45%45%7%35%
2112
April1st to 15thDay
11%6%36%5%35%5%5%6%39%
2118
16th to endDay
15%5%26%6%34446%40%
2232
May1st to 15thDay
18%5%36%6%35%6%47%31%
2331
16th to endDay
14%425%6%36%5%6%7%36%
2533
June1st to 15thDay
10%3245%35%6%7%9%39%
2520
16th to endDay
9%335%5%46%6%8%9%37%
2520
July1st to 15thDay
9%5%36%6%46%7%7%9%33%
2408
16th to endDay
8%425%7%47%6%8%9%35%
2465
August1st to 15thDay
9%6%26%6%47%6%7%9%33%
2340
16th to endDay
10%425%5%45%6%7%10%37%
2357
September1st to 15thDay
13%4245%35%45%7%42%
2145
16th to endDay
16%5%25%5%25%5%5%6%39%
1953
October1st to 15thDay
18%5%24423446%42%
1800
16th to endDay
12%6%25%5%2445%5%44%
1920
November1st to 15thDay
10%5%35%43445%5%47%
1831
16th to endDay
14%8%25%6%245%5%5%38%
1560
December1st to 15thDay
14%7%25%435%6%7%6%34%
1451
16th to endDay
14%9%36%5%36%5%6%6%32%
1536
January1st to 15thNight
10%7%36%6%35%5%6%7%38%
2327
16th to endNight
11%9%35%5%36%5%5%6%38%
2496
February1st to 15thNight
9%7%35%5%35%45%7%41%
2285
16th to endNight
8%6%36%6%48%6%6%8%35%
1928
March1st to 15thNight
13%5%245%345%5%7%41%
1968
16th to endNight
14%6%25%425%45%7%40%
2112
April1st to 15thNight
10%6%345%345%6%7%41%
1829
16th to endNight
14%424435%447%43%
1738
May1st to 15thNight
16%5%25%5%3446%9%35%
1620
16th to endNight
12%41443445%9%45%
1580
June1st to 15thNight
9%313426%46%10%47%
1440
16th to endNight
7%313435%5%6%10%46%
1440
July1st to 15thNight
9%425%5%345%6%9%43%
1548
16th to endNight
6%313416%5%8%11%47%
1703
August1st to 15thNight
7%314425%5%7%9%46%
1620
16th to endNight
8%3233245%49%50%
1833
September1st to 15thNight
11%5%1342445%7%49%
1812
16th to endNight
13%3144245%5%7%47%
2007
October1st to 15thNight
17%42432345%7%45%
2160
16th to endNight
12%413424447%49%
2304
November1st to 15thNight
11%7%25%324446%46%
2355
16th to endNight
12%5%25%6%35%5%5%7%40%
2730
December1st to 15thNight
12%6%36%5%47%5%6%6%35%
2546
16th to endNight
11%7%35%5%36%5%6%7%35%
2685

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
11%7%37%7%46%5%5%6%35%
1611
16th to endDay
10%8%48%6%3445%6%36%
1728
February1st to 15thDay
10%10%46%6%35%5%5%7%35%
1575
16th to endDay
7%8%49%6%35%446%39%
1541
March1st to 15thDay
12%8%37%5%3434440%
1980
16th to endDay
12%7%36%6%35%5%5%7%35%
2111
April1st to 15thDay
10%6%45%5%45%5%47%40%
2118
16th to endDay
15%5%25%5%35%45%7%40%
2232
May1st to 15thDay
18%5%26%6%36%5%5%7%31%
2331
16th to endDay
13%425%6%36%5%7%7%36%
2533
June1st to 15thDay
10%325%5%36%6%7%9%39%
2520
16th to endDay
9%325%6%36%6%7%10%37%
2520
July1st to 15thDay
9%5%36%7%5%5%7%6%9%33%
2408
16th to endDay
7%5%247%47%6%8%9%36%
2465
August1st to 15thDay
8%5%26%7%46%7%6%9%34%
2340
16th to endDay
10%4245%45%6%8%10%37%
2357
September1st to 15thDay
12%426%5%35%45%7%42%
2145
16th to endDay
14%6%25%5%35%5%47%39%
1953
October1st to 15thDay
18%425%433346%42%
1800
16th to endDay
12%7%25%5%24446%44%
1920
November1st to 15thDay
10%5%3443445%5%47%
1831
16th to endDay
13%7%35%5%3445%6%39%
1560
December1st to 15thDay
13%8%34435%6%7%6%35%
1451
16th to endDay
15%9%36%5%35%5%6%6%32%
1536
January1st to 15thNight
10%6%37%5%35%5%6%7%37%
2327
16th to endNight
10%9%46%5%35%5%46%38%
2496
February1st to 15thNight
9%8%25%5%36%45%7%41%
2278
16th to endNight
8%5%35%6%48%6%7%8%35%
1928
March1st to 15thNight
12%5%25%6%25%45%8%41%
1980
16th to endNight
13%6%35%42446%6%40%
2112
April1st to 15thNight
11%6%345%345%6%7%41%
1829
16th to endNight
14%4245%25%5%5%6%43%
1738
May1st to 15thNight
15%5%26%5%35%5%5%8%35%
1619
16th to endNight
12%3244345%6%8%45%
1580
June1st to 15thNight
8%413436%45%9%47%
1440
16th to endNight
7%3145%35%5%6%10%46%
1440
July1st to 15thNight
9%425%4445%6%9%43%
1548
16th to endNight
5%2134346%7%11%47%
1703
August1st to 15thNight
6%4135%35%6%6%9%46%
1620
16th to endNight
8%31442445%9%49%
1833
September1st to 15thNight
11%32343346%6%49%
1812
16th to endNight
12%31442445%7%46%
2007
October1st to 15thNight
16%4233235%47%45%
2160
16th to endNight
12%31343335%6%50%
2304
November1st to 15thNight
10%7%2442445%6%46%
2355
16th to endNight
12%5%25%5%35%45%6%41%
2730
December1st to 15thNight
12%6%36%6%36%5%6%6%36%
2546
16th to endNight
11%7%36%5%36%6%5%7%35%
2685

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
48%9%11%17%10%1
1612
16th to endDay
47%7%15%17%10%1
1728
February1st to 15thDay
48%7%14%17%11%1
1577
16th to endDay
46%7%14%21%8%
1541
March1st to 15thDay
46%6%12%21%11%2
1980
16th to endDay
48%8%11%18%12%1
2112
April1st to 15thDay
42%8%10%19%15%2
2118
16th to endDay
43%6%11%19%15%3
2232
May1st to 15thDay
50%8%12%16%10%
2331
16th to endDay
44%9%12%20%9%2
2537
June1st to 15thDay
39%12%14%21%12%
2520
16th to endDay
38%12%16%18%11%1
2520
July1st to 15thDay
44%12%12%16%10%2
2268
16th to endDay
39%11%15%17%13%1
2310
August1st to 15thDay
43%12%15%17%10%
2327
16th to endDay
38%12%15%21%10%1
2357
September1st to 15thDay
40%8%12%18%18%1
2145
16th to endDay
43%8%10%20%15%1
1953
October1st to 15thDay
41%6%10%24%13%3
1800
16th to endDay
39%7%10%24%16%1
1920
November1st to 15thDay
37%7%11%20%18%5%
1831
16th to endDay
44%7%11%19%15%1
1560
December1st to 15thDay
47%9%13%18%9%1
1451
16th to endDay
52%9%11%17%9%
1536
January1st to 15thNight
43%10%14%16%12%3
2327
16th to endNight
46%7%14%19%10%1
2496
February1st to 15thNight
41%8%14%21%12%1
2287
16th to endNight
44%10%13%20%9%
1928
March1st to 15thNight
42%8%13%25%7%1
1980
16th to endNight
43%9%13%21%12%1
2112
April1st to 15thNight
41%8%11%21%14%2
1829
16th to endNight
40%8%12%18%15%5%
1738
May1st to 15thNight
44%8%14%19%11%1
1620
16th to endNight
36%10%16%21%12%1
1582
June1st to 15thNight
33%10%14%28%12%
1440
16th to endNight
31%10%17%23%15%1
1440
July1st to 15thNight
37%11%17%19%11%2
1459
16th to endNight
26%11%20%23%16%1
1595
August1st to 15thNight
31%11%15%24%15%
1609
16th to endNight
30%7%14%30%14%1
1833
September1st to 15thNight
32%8%16%19%19%2
1812
16th to endNight
35%7%12%23%20%
2007
October1st to 15thNight
37%7%12%24%16%2
2160
16th to endNight
35%6%12%26%18%1
2304
November1st to 15thNight
37%6%11%20%16%6%
2355
16th to endNight
42%7%12%20%15%2
2730
December1st to 15thNight
47%9%13%18%10%1
2546
16th to endNight
45%10%14%18%9%
2685

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%27%22%10%7%2
90
16th to endDay
40%19%27%8%4
96
February1st to 15thDay
38%33%23%4
90
16th to endDay
25%27%26%18%
143
March1st to 15thDay
24%24%24%20%5%
270
16th to endDay
21%20%33%16%6%2
288
April1st to 15thDay
17%24%25%20%10%1
270
16th to endDay
20%11%28%20%14%4
270
May1st to 15thDay
28%16%21%18%9%5%
288
16th to endDay
20%11%20%22%17%7%
331
June1st to 15thDay
14%10%25%22%20%6%
315
16th to endDay
13%12%29%24%14%5%
315
July1st to 15thDay
13%7%36%23%14%5%
305
16th to endDay
9%219%33%23%11%
326
August1st to 15thDay
12%6%20%26%22%12%
313
16th to endDay
10%315%26%25%17%
332
September1st to 15thDay
14%8%18%20%22%14%
315
16th to endDay
21%418%19%24%12%
314
October1st to 15thDay
22%7%19%25%19%5%
315
16th to endDay
20%18%27%19%11%2
336
November1st to 15thDay
17%15%24%24%17%1
275
16th to endDay
26%17%31%12%11%1
90
December1st to 15thDay
38%19%19%14%44
63
16th to endDay
42%20%18%17%1
64
January1st to 15thNight
23%26%30%16%2
720
16th to endNight
24%25%33%15%
768
February1st to 15thNight
22%25%34%16%
704
16th to endNight
22%26%32%17%
631
March1st to 15thNight
24%20%31%19%4
720
16th to endNight
22%19%32%18%6%1
768
April1st to 15thNight
21%20%31%21%5%
718
16th to endNight
20%12%23%32%9%
658
May1st to 15thNight
18%10%24%32%12%
540
16th to endNight
15%6%20%35%19%2
461
June1st to 15thNight
10%426%38%19%1
360
16th to endNight
7%5%26%43%15%1
360
July1st to 15thNight
10%317%43%23%1
439
16th to endNight
6%216%36%33%4
564
August1st to 15thNight
8%15%45%26%2
539
16th to endNight
10%114%37%33%3
687
September1st to 15thNight
14%5%16%33%27%2
720
16th to endNight
14%5%19%27%29%3
717
October1st to 15thNight
21%9%19%27%19%3
720
16th to endNight
18%17%27%24%10%1
768
November1st to 15thNight
16%14%25%29%13%1
760
16th to endNight
20%22%24%23%7%
780
December1st to 15thNight
21%20%28%23%5%
728
16th to endNight
22%21%35%19%1
768
Page generated at 2017-12-03 11:16:46. Version ac04

Copyright 2017 A. Danko


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