Bee Sting Hill Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bee Sting Hill Observatory clear sky chart from 2005-11-05 to 2017-12-20.

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%
15846
21%
48086
15%
15803
54%
15803
25%
30685

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
24%
720
19%
2327
10%
716
37%
716
15%
1577
January16th to endNight
25%
768
21%
2463
10%
768
38%
768
17%
1644
February1st to 15thNight
28%
704
21%
2112
9%
701
38%
701
21%
1384
February16th to endNight
21%
631
20%
1893
8%
631
32%
631
17%
1293
March1st to 15thNight
27%
720
20%
2070
11%
720
35%
720
21%
1403
March16th to endNight
35%
768
18%
2112
11%
768
40%
768
25%
1393
April1st to 15thNight
40%
620
24%
1878
15%
620
51%
620
30%
1118
April16th to endNight
47%
540
24%
1694
16%
540
55%
540
29%
1026
May1st to 15thNight
48%
540
17%
1620
11%
540
54%
540
26%
1050
May16th to endNight
65%
561
18%
1683
13%
561
68%
561
30%
1057
June1st to 15thNight
70%
540
14%
1620
12%
540
72%
540
29%
1027
June16th to endNight
78%
540
15%
1620
13%
540
79%
540
33%
992
July1st to 15thNight
73%
510
13%
1530
13%
510
73%
510
27%
985
July16th to endNight
78%
564
16%
1595
14%
531
78%
531
29%
1027
August1st to 15thNight
77%
539
18%
1622
18%
536
77%
536
29%
1041
August16th to endNight
67%
573
19%
1910
19%
573
69%
573
24%
1235
September1st to 15thNight
62%
695
17%
1955
15%
695
63%
695
26%
1311
September16th to endNight
63%
717
26%
1980
22%
717
66%
717
33%
1233
October1st to 15thNight
55%
720
33%
1991
26%
720
61%
720
38%
1153
October16th to endNight
48%
768
33%
2311
25%
768
59%
768
33%
1325
November1st to 15thNight
50%
760
28%
2471
23%
760
58%
760
31%
1395
November16th to endNight
38%
780
27%
2535
18%
780
51%
780
25%
1519
December1st to 15thNight
34%
780
19%
2535
13%
780
43%
780
19%
1675
December16th to endNight
29%
788
18%
2559
13%
788
38%
788
16%
1822

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
11%7%36%6%35%5%5%7%36%
48746
Night
9%6%35%5%35%45%7%42%
48284
TransparencyDay
44%7%11%17%15%3
48447
Night
38%7%12%20%17%4
48087
SeeingDay
15%8%20%21%19%14%
5672
Night
14%10%20%27%22%4
15848

By Month

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
13%9%46%6%25%445%37%
1611
16th to endDay
13%9%36%43444440%
1758
February1st to 15thDay
12%10%46%6%245%46%35%
1750
16th to endDay
13%8%38%5%35%445%37%
1580
March1st to 15thDay
13%8%36%425%45%7%35%
1888
16th to endDay
11%8%26%6%3435%7%37%
2111
April1st to 15thDay
10%6%35%6%35%5%5%6%41%
2079
16th to endDay
11%6%36%5%3445%7%42%
2265
May1st to 15thDay
11%6%36%5%36%5%5%7%37%
2331
16th to endDay
9%6%37%7%36%5%6%8%35%
2431
June1st to 15thDay
7%5%37%7%5%8%8%8%9%29%
2340
16th to endDay
5%425%6%47%7%8%11%36%
2340
July1st to 15thDay
10%6%47%8%48%7%8%10%23%
2340
16th to endDay
8%5%37%9%6%9%8%7%9%25%
2465
August1st to 15thDay
7%426%8%5%8%8%8%10%28%
2323
16th to endDay
13%7%37%9%5%6%7%5%7%25%
2292
September1st to 15thDay
12%8%37%8%46%5%6%8%28%
1992
16th to endDay
14%5%25%5%345%5%9%39%
1980
October1st to 15thDay
11%324424445%53%
1968
16th to endDay
11%6%2432233357%
1911
November1st to 15thDay
11%5%24323335%52%
1717
16th to endDay
12%7%2432445%6%46%
1755
December1st to 15thDay
12%8%5%7%5%35%45%6%35%
1755
16th to endDay
17%10%35%6%24436%34%
1764
January1st to 15thNight
13%7%36%6%35%5%4437%
2327
16th to endNight
12%9%46%6%25%345%39%
2463
February1st to 15thNight
11%8%46%5%34345%41%
2103
16th to endNight
12%9%47%6%35%34438%
1893
March1st to 15thNight
12%8%35%5%34446%39%
2070
16th to endNight
10%8%36%424346%43%
2112
April1st to 15thNight
9%5%14424448%48%
1878
16th to endNight
8%6%35%33345%8%47%
1694
May1st to 15thNight
10%6%25%5%35%5%6%7%41%
1619
16th to endNight
6%4245%25%5%8%11%42%
1682
June1st to 15thNight
5%3245%46%5%9%13%40%
1620
16th to endNight
32146%35%7%8%11%45%
1620
July1st to 15thNight
7%325%5%46%7%8%13%36%
1620
16th to endNight
43245%37%7%10%13%37%
1703
August1st to 15thNight
43245%46%6%8%11%41%
1633
16th to endNight
9%5%25%6%35%5%7%10%37%
1910
September1st to 15thNight
9%5%26%5%35%5%7%9%38%
1955
16th to endNight
8%5%25%425%45%8%48%
1980
October1st to 15thNight
9%413313346%57%
1991
16th to endNight
9%5%245%1323456%
2311
November1st to 15thNight
9%5%24423346%52%
2471
16th to endNight
10%7%25%423435%48%
2535
December1st to 15thNight
12%9%37%5%2445%6%37%
2535
16th to endNight
15%10%47%6%35%446%31%
2559

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
47%46%16%19%4
1612
16th to endDay
44%5%7%18%18%5%
1758
February1st to 15thDay
48%5%7%18%18%2
1752
16th to endDay
47%5%7%17%18%3
1580
March1st to 15thDay
47%6%8%14%18%4
1888
16th to endDay
46%5%12%19%13%2
2112
April1st to 15thDay
41%5%11%20%16%3
2079
16th to endDay
40%5%10%21%17%3
2265
May1st to 15thDay
44%8%10%20%13%3
2331
16th to endDay
43%10%12%17%12%2
2435
June1st to 15thDay
45%11%15%19%6%
2340
16th to endDay
37%10%16%20%12%2
2340
July1st to 15thDay
48%11%17%15%5%1
2201
16th to endDay
49%11%16%14%7%1
2310
August1st to 15thDay
44%12%16%16%8%1
2310
16th to endDay
54%10%12%14%7%1
2292
September1st to 15thDay
49%10%10%14%11%3
1992
16th to endDay
40%6%14%16%19%2
1980
October1st to 15thDay
32%6%9%17%27%6%
1968
16th to endDay
33%35%20%28%9%
1911
November1st to 15thDay
35%46%16%29%8%
1717
16th to endDay
37%46%17%26%7%
1755
December1st to 15thDay
48%5%8%16%15%5%
1755
16th to endDay
51%310%15%15%3
1764
January1st to 15thNight
48%5%7%16%18%4
2327
16th to endNight
47%47%17%18%5%
2463
February1st to 15thNight
44%38%18%18%5%
2112
16th to endNight
48%47%19%16%2
1893
March1st to 15thNight
45%5%9%17%16%5%
2070
16th to endNight
42%413%24%13%1
2112
April1st to 15thNight
33%5%12%23%20%4
1878
16th to endNight
34%6%10%24%19%4
1694
May1st to 15thNight
38%8%14%22%15%1
1620
16th to endNight
31%11%18%24%11%2
1684
June1st to 15thNight
32%12%23%23%7%1
1620
16th to endNight
28%11%21%20%14%2
1620
July1st to 15thNight
32%13%22%19%10%1
1530
16th to endNight
30%14%22%20%9%2
1595
August1st to 15thNight
32%12%18%22%12%1
1622
16th to endNight
38%9%19%20%10%1
1910
September1st to 15thNight
39%10%16%17%13%3
1955
16th to endNight
32%8%11%23%20%3
1980
October1st to 15thNight
29%5%10%21%26%7%
1991
16th to endNight
32%3419%29%10%
2311
November1st to 15thNight
33%36%19%26%10%
2471
16th to endNight
37%46%18%24%7%
2535
December1st to 15thNight
45%5%11%15%16%5%
2535
16th to endNight
53%47%16%14%3
2559

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
24%17%37%15%4
90
16th to endDay
22%31%36%6%3
96
February1st to 15thDay
24%23%44%7%
90
16th to endDay
28%24%34%11%1
81
March1st to 15thDay
25%14%35%16%6%1
178
16th to endDay
17%15%30%23%11%2
288
April1st to 15thDay
17%14%28%22%14%2
270
16th to endDay
15%7%25%26%18%5%
270
May1st to 15thDay
14%11%28%15%15%13%
288
16th to endDay
12%6%15%31%16%17%
331
June1st to 15thDay
10%210%26%24%25%
315
16th to endDay
7%118%20%24%27%
315
July1st to 15thDay
13%112%22%22%28%
305
16th to endDay
7%15%19%28%37%
326
August1st to 15thDay
10%113%22%21%30%
313
16th to endDay
14%10%17%30%25%
332
September1st to 15thDay
12%5%13%14%35%18%
315
16th to endDay
14%28%29%30%13%
314
October1st to 15thDay
14%5%18%30%22%8%
315
16th to endDay
15%11%17%23%25%5%
327
November1st to 15thDay
24%8%27%26%10%2
135
16th to endDay
17%12%33%22%13%1
135
December1st to 15thDay
27%21%27%21%2
135
16th to endDay
30%15%38%12%2
108
January1st to 15thNight
23%20%26%22%5%
720
16th to endNight
20%19%30%25%3
768
February1st to 15thNight
22%17%28%27%3
704
16th to endNight
21%23%30%22%3
631
March1st to 15thNight
18%19%31%23%5%
720
16th to endNight
17%13%27%28%12%
768
April1st to 15thNight
13%16%26%29%12%1
620
16th to endNight
12%10%25%33%17%
540
May1st to 15thNight
12%6%25%31%20%4
540
16th to endNight
8%214%33%32%7%
563
June1st to 15thNight
6%13%29%40%9%
540
16th to endNight
47%30%42%14%
540
July1st to 15thNight
7%16%23%48%11%
510
16th to endNight
5%5%20%51%16%
564
August1st to 15thNight
6%15%25%48%12%
539
16th to endNight
11%8%23%45%10%
573
September1st to 15thNight
11%210%26%41%8%
695
16th to endNight
10%214%35%33%4
717
October1st to 15thNight
12%6%20%29%24%5%
720
16th to endNight
13%10%21%30%22%2
768
November1st to 15thNight
14%9%20%31%20%4
760
16th to endNight
18%14%24%26%14%
780
December1st to 15thNight
19%15%25%28%9%1
780
16th to endNight
24%16%26%26%6%
788
Page generated at 2017-12-21 07:04:44. Version ac04

Copyright 2017 A. Danko


Bee Sting Hill Observatory Clear Sky Chart |Charts Home