Bethune Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bethune Beach clear sky chart from 2005-11-05 to 2017-09-21.

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
52%
16053
19%
46955
14%
16014
58%
16014
24%
30428

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%
716
18%
2327
11%
716
47%
716
18%
1493
January16th to endNight
37%
768
23%
2496
15%
768
48%
768
23%
1552
February1st to 15thNight
41%
701
23%
2119
14%
698
52%
698
25%
1288
February16th to endNight
42%
631
24%
1791
13%
631
53%
631
27%
1092
March1st to 15thNight
48%
720
29%
1980
16%
720
60%
720
35%
1126
March16th to endNight
51%
768
23%
2112
16%
768
56%
768
32%
1255
April1st to 15thNight
52%
718
23%
1970
15%
718
58%
718
32%
1169
April16th to endNight
57%
720
24%
1800
13%
720
62%
720
33%
1129
May1st to 15thNight
61%
627
25%
1707
17%
627
64%
627
35%
1002
May16th to endNight
60%
561
21%
1682
15%
561
64%
561
26%
1062
June1st to 15thNight
59%
540
14%
1620
10%
540
61%
540
23%
1079
June16th to endNight
60%
540
10%
1620
8%
540
61%
540
21%
1110
July1st to 15thNight
65%
510
8%
1530
7%
510
65%
510
21%
1063
July16th to endNight
63%
564
10%
1595
10%
531
67%
531
23%
1082
August1st to 15thNight
71%
539
8%
1609
7%
536
71%
536
23%
1086
August16th to endNight
62%
757
10%
1985
8%
757
62%
757
22%
1433
September1st to 15thNight
60%
720
7%
1980
7%
720
60%
720
18%
1512
September16th to endNight
51%
681
11%
1881
7%
681
55%
681
13%
1479
October1st to 15thNight
58%
660
23%
1915
23%
660
61%
660
23%
1275
October16th to endNight
55%
704
23%
2112
21%
704
61%
704
26%
1330
November1st to 15thNight
50%
700
22%
2101
19%
700
55%
700
22%
1363
November16th to endNight
45%
720
23%
2187
16%
720
55%
720
23%
1403
December1st to 15thNight
44%
720
24%
2340
18%
720
54%
720
22%
1468
December16th to endNight
44%
768
21%
2496
15%
768
53%
768
20%
1577

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
8%5%26%6%36%6%7%9%37%
47886
Night
8%5%25%5%35%5%6%9%41%
47163
TransparencyDay
36%9%17%20%12%3
47587
Night
37%8%15%20%13%4
46966
SeeingDay
8%9%10%21%29%21%
5889
Night
9%16%11%21%28%12%
16063

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
10%6%36%5%36%5%5%7%39%
1611
16th to endDay
11%5%25%5%245%5%8%42%
1728
February1st to 15thDay
9%435%6%25%447%43%
1732
16th to endDay
9%6%25%5%3445%7%46%
1681
March1st to 15thDay
5%3245%35%45%8%50%
1980
16th to endDay
7%425%4245%5%8%48%
2111
April1st to 15thDay
6%2245%35%5%6%9%47%
1976
16th to endDay
5%4245%36%6%6%9%47%
2160
May1st to 15thDay
5%3244246%6%9%49%
2252
16th to endDay
7%325%6%45%7%9%9%37%
2431
June1st to 15thDay
8%437%7%5%7%7%7%11%29%
2340
16th to endDay
8%5%26%7%37%8%8%10%29%
2340
July1st to 15thDay
8%436%6%47%9%10%11%28%
2340
16th to endDay
7%5%36%8%5%8%9%7%10%26%
2465
August1st to 15thDay
5%426%8%5%7%8%10%12%28%
2334
16th to endDay
9%6%46%7%46%6%7%10%29%
2205
September1st to 15thDay
9%5%36%9%6%8%8%8%9%25%
1980
16th to endDay
12%7%38%8%47%7%8%10%21%
1872
October1st to 15thDay
9%6%27%7%5%47%6%9%33%
1713
16th to endDay
11%5%25%436%45%8%41%
1760
November1st to 15thDay
5%5%26%6%45%6%6%8%43%
1757
16th to endDay
9%5%36%7%35%5%5%8%39%
1770
December1st to 15thDay
10%5%36%6%35%5%6%8%39%
1620
16th to endDay
8%5%36%436%6%7%8%40%
1728
January1st to 15thNight
11%6%35%5%345%6%9%38%
2327
16th to endNight
13%5%246%2445%7%43%
2496
February1st to 15thNight
10%5%244245%46%49%
2118
16th to endNight
8%415%5%245%47%50%
1791
March1st to 15thNight
5%31332345%8%57%
1980
16th to endNight
6%314424446%55%
2112
April1st to 15thNight
5%41442446%9%51%
1970
16th to endNight
6%4135%35%5%5%7%50%
1800
May1st to 15thNight
6%213335%45%9%53%
1707
16th to endNight
7%3245%35%7%8%12%39%
1682
June1st to 15thNight
7%6%36%5%45%6%6%11%35%
1620
16th to endNight
6%6%37%6%5%6%5%8%10%33%
1620
July1st to 15thNight
6%425%6%38%6%8%11%34%
1620
16th to endNight
5%5%36%6%36%7%7%10%36%
1703
August1st to 15thNight
3325%7%5%5%8%9%11%35%
1620
16th to endNight
8%6%36%6%46%6%7%12%31%
1985
September1st to 15thNight
8%6%36%8%47%8%8%10%27%
1980
16th to endNight
10%6%29%8%47%8%8%10%21%
1881
October1st to 15thNight
7%6%26%6%35%5%6%9%38%
1915
16th to endNight
11%5%25%423449%44%
2112
November1st to 15thNight
6%5%36%6%46%5%6%7%41%
2101
16th to endNight
9%426%6%35%5%6%8%41%
2187
December1st to 15thNight
10%5%35%5%35%46%8%41%
2340
16th to endNight
8%6%35%5%35%5%7%8%40%
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
41%6%12%19%15%4
1612
16th to endDay
38%5%10%17%18%8%
1728
February1st to 15thDay
39%5%9%16%21%8%
1734
16th to endDay
36%5%11%19%19%7%
1681
March1st to 15thDay
27%5%13%30%18%4
1980
16th to endDay
31%6%14%22%19%5%
2112
April1st to 15thDay
28%7%12%24%21%4
1976
16th to endDay
28%7%13%24%20%6%
2160
May1st to 15thDay
26%8%13%25%20%5%
2252
16th to endDay
30%10%19%24%13%1
2435
June1st to 15thDay
41%11%19%23%4
2340
16th to endDay
39%13%26%17%4
2340
July1st to 15thDay
37%17%26%16%1
2201
16th to endDay
37%16%25%18%1
2310
August1st to 15thDay
34%16%33%14%1
2321
16th to endDay
40%15%27%15%1
2205
September1st to 15thDay
41%17%23%13%4
1980
16th to endDay
47%13%19%12%5%1
1872
October1st to 15thDay
39%9%11%16%16%5%
1713
16th to endDay
36%5%9%19%19%8%
1760
November1st to 15thDay
34%6%10%22%20%5%
1757
16th to endDay
40%5%9%19%17%7%
1770
December1st to 15thDay
41%7%11%23%12%3
1620
16th to endDay
37%6%15%20%13%6%
1728
January1st to 15thNight
43%5%11%20%14%4
2327
16th to endNight
39%5%9%18%19%7%
2496
February1st to 15thNight
35%5%9%18%18%12%
2127
16th to endNight
34%5%14%19%19%6%
1791
March1st to 15thNight
25%5%13%30%17%6%
1980
16th to endNight
29%6%13%21%20%8%
2112
April1st to 15thNight
28%7%14%22%18%8%
1970
16th to endNight
30%6%12%25%19%5%
1800
May1st to 15thNight
26%7%14%25%19%6%
1708
16th to endNight
32%10%16%24%14%1
1684
June1st to 15thNight
39%9%21%24%4
1620
16th to endNight
41%10%23%19%4
1620
July1st to 15thNight
39%14%27%16%2
1530
16th to endNight
36%14%28%18%2
1595
August1st to 15thNight
34%15%36%12%1
1609
16th to endNight
42%13%26%16%1
1985
September1st to 15thNight
46%15%20%13%4
1980
16th to endNight
53%12%14%14%31
1881
October1st to 15thNight
41%7%10%17%17%5%
1915
16th to endNight
37%6%9%17%20%7%
2112
November1st to 15thNight
40%7%10%17%19%5%
2101
16th to endNight
40%5%10%19%16%8%
2187
December1st to 15thNight
40%5%12%25%11%4
2340
16th to endNight
40%6%13%22%11%6%
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
21%227%26%12%10%
90
16th to endDay
13%9%28%32%13%3
96
February1st to 15thDay
6%5%31%31%20%5%
90
16th to endDay
10%12%25%39%12%
182
March1st to 15thDay
5%18%21%34%18%2
270
16th to endDay
9%14%19%26%25%4
288
April1st to 15thDay
313%19%32%23%7%
270
16th to endDay
7%11%9%25%38%7%
270
May1st to 15thDay
410%12%29%32%10%
288
16th to endDay
49%5%16%39%24%
331
June1st to 15thDay
7%9%5%14%33%28%
315
16th to endDay
7%9%111%29%40%
315
July1st to 15thDay
46%1429%53%
305
16th to endDay
9%9%16%35%38%
326
August1st to 15thDay
6%5%210%37%36%
313
16th to endDay
12%6%28%27%43%
332
September1st to 15thDay
12%5%49%34%33%
315
16th to endDay
13%6%210%34%31%
275
October1st to 15thDay
15%6%9%27%30%9%
255
16th to endDay
8%7%14%34%27%6%
272
November1st to 15thDay
7%11%9%30%29%12%
265
16th to endDay
9%12%20%31%21%5%
240
December1st to 15thDay
5%421%45%22%1
90
16th to endDay
10%27%31%42%6%
96
January1st to 15thNight
11%22%20%25%15%3
720
16th to endNight
12%23%23%25%15%
768
February1st to 15thNight
11%21%20%28%14%2
704
16th to endNight
9%20%22%35%11%
631
March1st to 15thNight
5%20%21%30%18%2
720
16th to endNight
7%19%17%28%22%4
768
April1st to 15thNight
6%19%16%28%25%5%
718
16th to endNight
7%18%9%29%29%4
720
May1st to 15thNight
6%17%8%28%32%5%
628
16th to endNight
7%17%6%16%35%17%
563
June1st to 15thNight
8%17%313%37%19%
540
16th to endNight
6%17%110%35%29%
540
July1st to 15thNight
6%11%27%37%33%
510
16th to endNight
416%17%40%29%
564
August1st to 15thNight
49%27%41%34%
539
16th to endNight
10%8%38%38%30%
757
September1st to 15thNight
11%8%213%39%24%
720
16th to endNight
14%9%5%11%37%21%
681
October1st to 15thNight
10%11%8%22%38%10%
660
16th to endNight
13%11%11%25%30%8%
704
November1st to 15thNight
8%17%14%29%23%6%
700
16th to endNight
10%19%17%28%19%4
720
December1st to 15thNight
9%20%16%21%23%7%
720
16th to endNight
10%20%15%24%25%3
768
Page generated at 2017-09-22 07:35:32. Version ac04

Copyright 2017 A. Danko


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