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 2019-06-24.

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
59%
17664
23%
54070
19%
17622
64%
17622
31%
32440

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
37%
840
24%
2650
13%
836
50%
836
28%
1595
January16th to endNight
39%
896
24%
2688
13%
896
49%
896
25%
1737
February1st to 15thNight
40%
822
24%
2470
13%
820
50%
820
27%
1558
February16th to endNight
44%
735
25%
2205
15%
735
52%
735
30%
1365
March1st to 15thNight
48%
840
25%
2480
15%
840
56%
840
32%
1482
March16th to endNight
57%
893
26%
2461
17%
893
63%
893
38%
1440
April1st to 15thNight
56%
629
26%
2097
22%
629
63%
629
30%
1199
April16th to endNight
66%
624
29%
2078
28%
624
72%
624
42%
1029
May1st to 15thNight
70%
629
26%
1963
25%
629
73%
629
40%
1057
May16th to endNight
77%
657
23%
1970
21%
657
78%
657
39%
1098
June1st to 15thNight
74%
630
15%
1890
15%
630
75%
630
31%
1145
June16th to endNight
78%
609
16%
1828
15%
609
78%
609
33%
1084
July1st to 15thNight
79%
555
12%
1665
13%
555
79%
555
30%
1051
July16th to endNight
79%
612
9%
1852
11%
579
80%
579
27%
1159
August1st to 15thNight
76%
575
9%
1906
11%
572
76%
572
24%
1225
August16th to endNight
67%
621
14%
2070
16%
621
67%
621
22%
1387
September1st to 15thNight
69%
712
12%
2077
12%
712
70%
712
26%
1392
September16th to endNight
69%
777
25%
2145
21%
777
71%
777
34%
1342
October1st to 15thNight
70%
780
33%
2145
28%
780
73%
780
42%
1238
October16th to endNight
61%
832
34%
2392
29%
832
66%
832
40%
1341
November1st to 15thNight
61%
820
29%
2666
28%
820
68%
820
36%
1452
November16th to endNight
54%
840
29%
2730
25%
840
63%
840
35%
1497
December1st to 15thNight
45%
840
26%
2730
20%
840
54%
840
28%
1659
December16th to endNight
43%
896
19%
2912
15%
896
49%
896
22%
1908

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%45%
54726
Night
9%4244245%5%8%47%
54282
TransparencyDay
33%9%15%19%16%6%
54437
Night
33%7%14%19%17%7%
54075
SeeingDay
10%214%25%28%17%
7559
Night
11%317%26%30%10%
17669

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
11%5%15%42445%8%45%
1944
16th to endDay
14%5%25%42445%5%44%
2240
February1st to 15thDay
14%6%25%32435%6%44%
2050
16th to endDay
13%42442335%6%47%
1840
March1st to 15thDay
8%42432445%7%51%
2138
16th to endDay
9%424424346%53%
2477
April1st to 15thDay
10%4144245%5%6%49%
2511
16th to endDay
5%21332445%8%58%
2487
May1st to 15thDay
431432346%9%55%
2643
16th to endDay
5%314335%6%6%10%49%
2847
June1st to 15thDay
6%425%5%36%6%8%11%39%
2730
16th to endDay
6%424426%7%9%14%36%
2639
July1st to 15thDay
6%4246%5%8%9%11%13%28%
2535
16th to endDay
7%335%6%47%7%11%14%29%
2547
August1st to 15thDay
9%426%6%48%9%11%13%24%
2295
16th to endDay
10%5%25%5%36%7%8%9%35%
2484
September1st to 15thDay
9%5%345%36%7%9%10%34%
2200
16th to endDay
6%4145%35%6%7%10%44%
2145
October1st to 15thDay
6%31342446%7%56%
2145
16th to endDay
8%21342334460%
2181
November1st to 15thDay
9%5%23313346%55%
1852
16th to endDay
8%323423345%56%
1890
December1st to 15thDay
12%6%2442335%7%48%
1890
16th to endDay
19%8%25%423346%37%
2016
January1st to 15thNight
12%5%25%42435%6%47%
2650
16th to endNight
15%6%3442345%6%42%
2688
February1st to 15thNight
14%6%245%23336%46%
2463
16th to endNight
14%5%24323446%47%
2205
March1st to 15thNight
10%4244245%5%8%47%
2480
16th to endNight
7%42442345%8%53%
2461
April1st to 15thNight
9%5%13425%5%5%8%47%
2097
16th to endNight
6%31332235%8%59%
2078
May1st to 15thNight
6%32342436%9%53%
1963
16th to endNight
43134345%7%10%52%
1970
June1st to 15thNight
44245%445%7%14%41%
1890
16th to endNight
6%323425%6%8%12%45%
1828
July1st to 15thNight
5%3245%35%7%7%12%42%
1755
16th to endNight
43245%45%8%10%15%36%
1969
August1st to 15thNight
6%4245%36%7%10%14%34%
1918
16th to endNight
8%436%6%35%6%7%9%37%
2070
September1st to 15thNight
7%425%6%45%7%7%13%34%
2077
16th to endNight
6%4146%346%6%8%46%
2145
October1st to 15thNight
5%4134335%47%56%
2145
16th to endNight
8%32342334458%
2392
November1st to 15thNight
8%5%14423347%54%
2666
16th to endNight
10%323423347%54%
2730
December1st to 15thNight
13%6%24424446%45%
2730
16th to endNight
16%7%35%42345%6%38%
2912

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
35%5%10%15%23%9%
1945
16th to endDay
40%5%7%16%21%9%
2240
February1st to 15thDay
40%5%8%15%21%8%
2052
16th to endDay
37%6%8%20%18%8%
1840
March1st to 15thDay
30%6%11%19%22%9%
2138
16th to endDay
31%5%15%18%19%10%
2478
April1st to 15thDay
32%6%10%22%19%8%
2511
16th to endDay
23%5%13%25%21%9%
2487
May1st to 15thDay
25%7%15%22%20%8%
2643
16th to endDay
25%9%18%23%19%2
2851
June1st to 15thDay
34%11%18%27%7%
2730
16th to endDay
32%13%24%22%7%
2639
July1st to 15thDay
38%17%25%15%2
2396
16th to endDay
38%16%26%14%2
2401
August1st to 15thDay
42%16%22%14%3
2283
16th to endDay
38%14%23%15%5%1
2484
September1st to 15thDay
38%12%21%14%10%2
2200
16th to endDay
31%11%16%19%15%6%
2145
October1st to 15thDay
26%6%11%21%22%11%
2145
16th to endDay
27%5%5%17%26%17%
2181
November1st to 15thDay
29%49%20%24%11%
1852
16th to endDay
29%47%22%22%14%
1890
December1st to 15thDay
35%5%12%18%20%7%
1890
16th to endDay
47%5%7%21%12%5%
2016
January1st to 15thNight
38%39%14%24%8%
2650
16th to endNight
42%46%14%22%9%
2688
February1st to 15thNight
39%47%15%21%11%
2472
16th to endNight
37%48%17%20%11%
2205
March1st to 15thNight
33%6%12%18%20%8%
2480
16th to endNight
28%5%10%24%19%10%
2461
April1st to 15thNight
33%6%10%18%22%9%
2097
16th to endNight
23%410%27%25%8%
2078
May1st to 15thNight
26%5%14%19%24%8%
1964
16th to endNight
25%8%18%23%19%4
1972
June1st to 15thNight
31%10%23%25%8%1
1890
16th to endNight
28%10%25%24%9%1
1828
July1st to 15thNight
29%14%30%21%4
1665
16th to endNight
30%15%32%18%3
1852
August1st to 15thNight
34%14%32%15%2
1906
16th to endNight
39%12%21%17%7%1
2070
September1st to 15thNight
38%11%23%15%9%2
2077
16th to endNight
32%8%16%20%18%4
2145
October1st to 15thNight
26%6%9%22%22%12%
2145
16th to endNight
29%45%17%24%19%
2392
November1st to 15thNight
30%46%20%25%13%
2666
16th to endNight
30%47%18%23%15%
2730
December1st to 15thNight
38%49%20%20%6%
2730
16th to endNight
44%6%9%20%14%6%
2912

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%32%31%12%2
180
16th to endDay
16%14%32%28%8%
192
February1st to 15thDay
21%6%32%29%10%
180
16th to endDay
10%437%41%6%
159
March1st to 15thDay
12%347%27%6%1
218
16th to endDay
11%426%35%19%2
416
April1st to 15thDay
12%7%20%35%21%2
390
16th to endDay
7%318%33%29%7%
379
May1st to 15thDay
6%216%34%30%10%
408
16th to endDay
9%5%24%37%22%
459
June1st to 15thDay
11%5%19%40%22%
435
16th to endDay
9%414%34%35%
407
July1st to 15thDay
418%36%47%
365
16th to endDay
7%413%33%42%
390
August1st to 15thDay
13%211%34%37%
358
16th to endDay
8%315%35%36%
396
September1st to 15thDay
12%18%17%35%24%
375
16th to endDay
7%422%44%19%
374
October1st to 15thDay
6%113%32%33%13%
375
16th to endDay
6%6%18%30%28%9%
371
November1st to 15thDay
20%215%30%28%2
180
16th to endDay
6%322%41%21%4
180
December1st to 15thDay
17%8%27%32%11%1
180
16th to endDay
29%219%35%11%1
192
January1st to 15thNight
15%8%33%28%13%1
840
16th to endNight
17%10%27%32%11%
896
February1st to 15thNight
17%8%27%32%13%
824
16th to endNight
15%6%29%35%12%
735
March1st to 15thNight
12%6%27%36%15%1
840
16th to endNight
10%5%20%35%26%2
893
April1st to 15thNight
11%221%32%29%2
629
16th to endNight
7%217%31%33%6%
624
May1st to 15thNight
8%111%32%36%9%
630
16th to endNight
5%7%21%51%14%
659
June1st to 15thNight
6%5%19%50%17%
630
16th to endNight
6%311%49%28%
609
July1st to 15thNight
6%18%42%39%
555
16th to endNight
5%29%45%36%
612
August1st to 15thNight
7%27%43%39%
575
16th to endNight
9%15%10%44%29%
621
September1st to 15thNight
10%16%15%43%23%
712
16th to endNight
8%9%25%41%14%
777
October1st to 15thNight
7%113%32%37%7%
780
16th to endNight
10%317%29%30%7%
832
November1st to 15thNight
10%418%35%27%3
820
16th to endNight
11%5%24%31%23%3
840
December1st to 15thNight
15%6%26%29%19%2
840
16th to endNight
18%6%25%31%16%1
896
Page generated at 2019-06-24 19:41:31. Version ac04

Copyright 2019 A. Danko


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