Blue Mountain Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blue Mountain Beach clear sky chart from 2005-11-05 to 2017-09-24.

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%
15373
23%
47061
19%
15331
65%
15331
31%
28138

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
39%
720
24%
2270
13%
716
51%
716
29%
1361
January16th to endNight
39%
768
24%
2304
13%
768
49%
768
25%
1494
February1st to 15thNight
41%
702
27%
2110
15%
700
52%
700
29%
1284
February16th to endNight
42%
631
24%
1893
13%
631
52%
631
29%
1171
March1st to 15thNight
50%
720
25%
2126
15%
720
58%
720
33%
1262
March16th to endNight
59%
765
26%
2109
19%
765
64%
765
38%
1233
April1st to 15thNight
58%
539
26%
1797
22%
539
64%
539
31%
1014
April16th to endNight
66%
540
29%
1800
28%
540
71%
540
41%
910
May1st to 15thNight
68%
539
24%
1682
23%
539
72%
539
38%
919
May16th to endNight
77%
561
23%
1682
21%
561
78%
561
38%
943
June1st to 15thNight
76%
540
16%
1620
15%
540
76%
540
34%
955
June16th to endNight
78%
540
17%
1620
17%
540
78%
540
32%
977
July1st to 15thNight
79%
510
11%
1530
11%
510
79%
510
30%
964
July16th to endNight
79%
564
10%
1698
11%
531
80%
531
26%
1067
August1st to 15thNight
77%
539
9%
1788
11%
536
77%
536
24%
1146
August16th to endNight
68%
573
15%
1910
18%
573
68%
573
22%
1270
September1st to 15thNight
68%
657
13%
1917
13%
657
69%
657
26%
1278
September16th to endNight
67%
693
25%
1914
21%
693
69%
693
32%
1215
October1st to 15thNight
71%
660
33%
1815
28%
660
74%
660
42%
1043
October16th to endNight
61%
704
33%
2024
29%
704
66%
704
39%
1147
November1st to 15thNight
62%
700
31%
2276
29%
700
70%
700
39%
1197
November16th to endNight
53%
720
29%
2340
26%
720
62%
720
35%
1285
December1st to 15thNight
49%
720
26%
2340
22%
720
56%
720
30%
1387
December16th to endNight
43%
768
20%
2496
16%
768
51%
768
22%
1616

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
9%424425%5%6%9%44%
47845
Night
9%4244245%5%8%47%
47273
TransparencyDay
33%8%15%19%15%6%
47556
Night
33%7%13%19%18%8%
47066
SeeingDay
10%212%24%30%20%
5303
Night
10%416%26%30%10%
15378

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
12%415%425%5%5%8%45%
1665
16th to endDay
15%5%25%424445%45%
1920
February1st to 15thDay
12%5%25%32335%6%48%
1750
16th to endDay
14%424423345%49%
1580
March1st to 15thDay
9%42432446%7%51%
1833
16th to endDay
10%32442435%6%52%
2123
April1st to 15thDay
11%3243245%6%6%49%
2151
16th to endDay
6%21331445%8%56%
2160
May1st to 15thDay
5%31432346%9%54%
2265
16th to endDay
4314335%6%7%10%49%
2431
June1st to 15thDay
6%425%5%35%5%8%12%40%
2340
16th to endDay
7%424436%6%9%14%35%
2340
July1st to 15thDay
6%4246%5%8%9%10%13%28%
2340
16th to endDay
7%335%6%37%7%11%13%29%
2349
August1st to 15thDay
9%5%26%6%48%9%11%13%23%
2160
16th to endDay
9%5%25%5%36%7%8%9%36%
2292
September1st to 15thDay
9%5%346%35%7%8%10%35%
2031
16th to endDay
6%415%5%35%6%6%10%44%
1905
October1st to 15thDay
6%31242446%7%57%
1815
16th to endDay
9%21342334459%
1845
November1st to 15thDay
8%42331335%7%57%
1582
16th to endDay
10%313432345%57%
1620
December1st to 15thDay
11%6%2432335%7%49%
1620
16th to endDay
19%7%35%423446%39%
1728
January1st to 15thNight
12%425%42435%6%47%
2270
16th to endNight
15%6%35%42445%6%42%
2304
February1st to 15thNight
13%6%24423335%50%
2103
16th to endNight
15%5%34323435%48%
1893
March1st to 15thNight
9%42442445%8%48%
2126
16th to endNight
7%32443445%8%53%
2109
April1st to 15thNight
9%413425%5%5%8%48%
1797
16th to endNight
7%31332335%8%57%
1800
May1st to 15thNight
6%32342436%9%52%
1682
16th to endNight
43133346%7%10%50%
1682
June1st to 15thNight
44235%445%8%15%41%
1620
16th to endNight
6%323425%6%8%11%44%
1620
July1st to 15thNight
43245%35%7%7%12%42%
1620
16th to endNight
43245%45%7%9%14%36%
1815
August1st to 15thNight
6%4245%37%7%10%14%33%
1800
16th to endNight
8%436%6%35%6%7%10%37%
1910
September1st to 15thNight
8%425%6%35%7%6%13%35%
1917
16th to endNight
7%5%246%346%6%7%45%
1914
October1st to 15thNight
5%4134335%47%57%
1815
16th to endNight
9%32342334457%
2024
November1st to 15thNight
7%413323347%56%
2276
16th to endNight
10%324423347%55%
2340
December1st to 15thNight
12%6%2341445%7%47%
2340
16th to endNight
16%6%35%4245%6%6%39%
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
36%5%10%14%23%9%
1666
16th to endDay
40%5%7%15%20%9%
1920
February1st to 15thDay
36%47%16%24%10%
1752
16th to endDay
36%5%7%20%20%9%
1580
March1st to 15thDay
30%6%11%21%22%7%
1833
16th to endDay
31%5%15%19%17%10%
2124
April1st to 15thDay
32%6%10%21%20%8%
2151
16th to endDay
24%6%15%25%21%7%
2160
May1st to 15thDay
26%8%15%21%19%9%
2265
16th to endDay
26%9%19%24%17%2
2435
June1st to 15thDay
33%10%19%28%7%
2340
16th to endDay
33%13%22%21%8%
2340
July1st to 15thDay
38%17%25%15%2
2201
16th to endDay
39%15%26%15%3
2203
August1st to 15thDay
42%16%22%14%4
2148
16th to endDay
38%13%23%16%6%1
2292
September1st to 15thDay
39%10%20%14%11%2
2031
16th to endDay
31%10%16%19%15%6%
1905
October1st to 15thDay
25%6%10%21%22%13%
1815
16th to endDay
27%5%416%26%18%
1845
November1st to 15thDay
27%48%20%25%13%
1582
16th to endDay
29%47%21%21%15%
1620
December1st to 15thDay
33%5%12%19%21%6%
1620
16th to endDay
46%5%7%21%12%6%
1728
January1st to 15thNight
37%39%14%25%9%
2270
16th to endNight
42%46%14%22%9%
2304
February1st to 15thNight
37%35%16%23%13%
2112
16th to endNight
38%47%15%21%12%
1893
March1st to 15thNight
33%5%11%20%22%7%
2126
16th to endNight
28%5%9%24%19%10%
2109
April1st to 15thNight
32%5%10%17%22%10%
1797
16th to endNight
24%411%28%23%7%
1800
May1st to 15thNight
28%5%14%20%22%9%
1683
16th to endNight
24%9%18%24%17%4
1684
June1st to 15thNight
29%9%24%27%8%
1620
16th to endNight
29%11%24%23%10%1
1620
July1st to 15thNight
30%13%31%20%4
1530
16th to endNight
31%14%32%18%3
1698
August1st to 15thNight
34%14%32%15%3
1788
16th to endNight
39%12%21%18%7%1
1910
September1st to 15thNight
38%10%21%16%10%2
1917
16th to endNight
34%8%15%19%17%4
1914
October1st to 15thNight
26%5%8%21%22%14%
1815
16th to endNight
30%35%14%25%20%
2024
November1st to 15thNight
27%35%20%26%15%
2276
16th to endNight
30%47%17%22%17%
2340
December1st to 15thNight
36%49%21%22%5%
2340
16th to endNight
42%6%8%20%14%7%
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
13%7%35%25%13%4
90
16th to endDay
22%16%26%26%7%1
96
February1st to 15thDay
10%8%34%26%18%1
90
16th to endDay
9%435%44%4
81
March1st to 15thDay
11%145%30%8%2
123
16th to endDay
12%421%34%23%3
288
April1st to 15thDay
11%6%20%34%24%2
270
16th to endDay
7%218%32%31%8%
270
May1st to 15thDay
6%318%30%29%11%
288
16th to endDay
9%17%24%36%20%
331
June1st to 15thDay
12%5%16%39%25%
315
16th to endDay
11%412%34%35%
315
July1st to 15thDay
326%36%50%
305
16th to endDay
7%212%33%43%
326
August1st to 15thDay
12%212%34%36%
313
16th to endDay
7%315%35%37%
332
September1st to 15thDay
13%18%18%33%23%
315
16th to endDay
9%15%25%41%17%
287
October1st to 15thDay
5%112%38%32%10%
255
16th to endDay
7%6%14%34%25%10%
247
November1st to 15thDay
18%212%31%32%3
90
16th to endDay
5%5%21%47%12%7%
90
December1st to 15thDay
14%426%38%14%1
90
16th to endDay
30%415%32%15%2
96
January1st to 15thNight
15%7%33%29%13%1
720
16th to endNight
17%10%26%32%11%
768
February1st to 15thNight
16%9%27%31%14%1
704
16th to endNight
16%7%30%34%11%
631
March1st to 15thNight
11%6%26%36%17%1
720
16th to endNight
10%418%35%27%2
765
April1st to 15thNight
10%220%32%31%2
539
16th to endNight
7%218%30%33%7%
540
May1st to 15thNight
9%211%32%34%9%
540
16th to endNight
47%22%51%12%
563
June1st to 15thNight
6%5%19%50%17%
540
16th to endNight
6%310%50%28%
540
July1st to 15thNight
6%28%42%39%
510
16th to endNight
5%29%45%36%
564
August1st to 15thNight
6%27%44%38%
539
16th to endNight
8%16%10%43%29%
573
September1st to 15thNight
10%16%15%43%22%
657
16th to endNight
9%10%27%40%11%
693
October1st to 15thNight
7%112%35%37%5%
660
16th to endNight
11%417%28%32%7%
704
November1st to 15thNight
9%419%35%28%3
700
16th to endNight
11%5%24%32%21%3
720
December1st to 15thNight
13%6%25%31%20%2
720
16th to endNight
17%7%25%31%16%1
768
Page generated at 2017-09-25 08:02:23. Version ac04

Copyright 2017 A. Danko


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