Grand Manan Island
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Grand Manan Island 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
30%
14931
12%
46845
7%
14889
37%
14889
15%
34584

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%
734
10%
2589
2%
730
24%
730
8%
1985
January16th to endNight
13%
768
8%
2573
1%
768
21%
768
7%
2081
February1st to 15thNight
16%
704
6%
2286
1%
701
22%
701
8%
1852
February16th to endNight
21%
631
11%
1954
3%
631
32%
631
12%
1487
March1st to 15thNight
21%
720
14%
2040
5%
720
30%
720
14%
1569
March16th to endNight
28%
768
16%
2112
8%
768
35%
768
18%
1537
April1st to 15thNight
26%
620
14%
1785
6%
620
33%
620
17%
1333
April16th to endNight
33%
540
15%
1620
9%
540
38%
540
19%
1157
May1st to 15thNight
35%
540
13%
1620
8%
540
40%
540
17%
1195
May16th to endNight
39%
552
11%
1509
8%
551
42%
551
19%
1144
June1st to 15thNight
36%
360
8%
1260
8%
360
38%
360
12%
960
June16th to endNight
43%
360
8%
1260
10%
360
44%
360
14%
934
July1st to 15thNight
49%
340
8%
1192
12%
340
49%
340
15%
842
July16th to endNight
44%
475
9%
1509
11%
445
46%
445
15%
1107
August1st to 15thNight
53%
539
11%
1608
10%
535
53%
535
19%
1163
August16th to endNight
55%
573
18%
1719
14%
573
56%
573
24%
1148
September1st to 15thNight
51%
641
16%
1892
13%
641
54%
641
26%
1247
September16th to endNight
47%
693
25%
1913
17%
693
54%
693
33%
1192
October1st to 15thNight
39%
660
19%
1948
11%
660
47%
660
23%
1289
October16th to endNight
27%
704
15%
2175
6%
704
36%
704
18%
1527
November1st to 15thNight
31%
709
14%
2334
8%
709
38%
709
16%
1644
November16th to endNight
26%
750
12%
2520
6%
750
34%
750
12%
1831
December1st to 15thNight
14%
750
9%
2547
2%
750
23%
750
9%
2025
December16th to endNight
11%
800
8%
2880
1%
800
19%
800
6%
2335

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
20%8%35%42445%6%33%
48083
Night
21%9%36%5%3445%6%29%
47016
TransparencyDay
51%5%11%20%10%1
47772
Night
56%5%10%18%9%
46845
SeeingDay
27%5%21%28%14%2
6838
Night
26%9%25%25%11%1
14931

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
18%11%5%7%6%45%35%5%26%
1346
16th to endDay
19%11%5%7%6%46%36%6%23%
1650
February1st to 15thDay
18%10%47%7%6%7%5%7%6%19%
1575
16th to endDay
15%11%46%5%26%5%6%6%29%
1518
March1st to 15thDay
18%11%5%6%5%34345%30%
1909
16th to endDay
17%8%35%424446%38%
2112
April1st to 15thDay
20%7%45%423345%37%
2161
16th to endDay
22%7%2442235%6%37%
2340
May1st to 15thDay
24%8%26%424346%31%
2332
16th to endDay
24%7%35%42345%7%31%
2614
June1st to 15thDay
26%8%35%423446%29%
2700
16th to endDay
23%8%45%32445%7%29%
2700
July1st to 15thDay
17%7%36%42445%8%34%
2696
16th to endDay
18%9%25%5%25%35%7%32%
2543
August1st to 15thDay
15%8%25%4345%5%7%37%
2340
16th to endDay
13%6%13424448%45%
2483
September1st to 15thDay
14%7%24412437%47%
2067
16th to endDay
17%6%23322246%48%
1906
October1st to 15thDay
19%6%33423346%42%
1680
16th to endDay
22%6%24434345%37%
1694
November1st to 15thDay
22%8%34422347%35%
1523
16th to endDay
21%9%36%5%2445%431%
1440
December1st to 15thDay
27%8%47%5%44446%21%
1410
16th to endDay
27%10%48%7%23445%20%
1344
January1st to 15thNight
19%11%47%6%34347%25%
2589
16th to endNight
17%12%38%6%46%5%6%6%20%
2573
February1st to 15thNight
20%9%48%7%46%45%7%20%
2285
16th to endNight
16%11%5%6%6%35%45%5%29%
1954
March1st to 15thNight
21%11%37%5%34345%28%
2028
16th to endNight
18%8%45%5%35%447%32%
2112
April1st to 15thNight
24%9%26%435%36%5%29%
1785
16th to endNight
23%9%25%5%2435%6%31%
1620
May1st to 15thNight
24%10%46%424345%31%
1620
16th to endNight
26%8%35%43435%6%28%
1507
June1st to 15thNight
30%9%36%5%33445%24%
1260
16th to endNight
26%9%36%5%2335%6%27%
1260
July1st to 15thNight
18%11%46%4345%5%8%27%
1262
16th to endNight
22%11%46%5%2446%6%25%
1613
August1st to 15thNight
18%8%36%5%345%6%7%30%
1620
16th to endNight
16%8%345%3335%7%38%
1719
September1st to 15thNight
17%7%34423347%40%
1892
16th to endNight
15%6%15%322336%47%
1913
October1st to 15thNight
20%6%25%424336%40%
1948
16th to endNight
21%8%25%423445%36%
2175
November1st to 15thNight
21%7%25%5%34446%34%
2334
16th to endNight
20%9%35%43445%6%31%
2520
December1st to 15thNight
27%10%37%5%2445%6%21%
2547
16th to endNight
26%12%5%6%7%24435%21%
2880

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
62%5%12%13%5%1
1347
16th to endDay
66%411%13%3
1650
February1st to 15thDay
65%7%11%10%3
1578
16th to endDay
54%6%13%18%5%1
1518
March1st to 15thDay
57%410%17%8%1
1920
16th to endDay
46%5%11%20%14%2
2112
April1st to 15thDay
48%38%20%16%1
2161
16th to endDay
47%310%21%14%2
2340
May1st to 15thDay
54%39%17%12%1
2332
16th to endDay
51%6%13%20%7%1
2618
June1st to 15thDay
55%5%11%17%8%1
2700
16th to endDay
53%5%9%19%10%
2700
July1st to 15thDay
48%5%13%21%10%
2537
16th to endDay
51%415%19%8%
2385
August1st to 15thDay
46%6%12%23%10%
2327
16th to endDay
38%5%14%26%14%
2483
September1st to 15thDay
38%412%25%17%1
2067
16th to endDay
38%38%32%15%1
1906
October1st to 15thDay
44%411%27%13%
1680
16th to endDay
48%413%23%8%
1694
November1st to 15thDay
52%5%12%19%9%
1523
16th to endDay
57%5%13%16%7%
1440
December1st to 15thDay
65%6%11%13%2
1410
16th to endDay
68%6%7%11%5%
1344
January1st to 15thNight
61%6%10%15%5%
2589
16th to endNight
66%6%10%13%3
2573
February1st to 15thNight
66%5%11%12%3
2286
16th to endNight
59%5%11%15%8%
1954
March1st to 15thNight
58%49%15%10%1
2040
16th to endNight
52%49%19%12%
2112
April1st to 15thNight
56%48%15%12%2
1785
16th to endNight
53%38%18%13%1
1620
May1st to 15thNight
56%48%17%11%1
1620
16th to endNight
56%410%20%7%
1509
June1st to 15thNight
62%410%16%5%1
1260
16th to endNight
58%5%8%18%9%
1260
July1st to 15thNight
52%6%12%16%11%
1192
16th to endNight
57%411%19%6%1
1509
August1st to 15thNight
52%5%12%21%8%
1608
16th to endNight
45%412%24%12%
1719
September1st to 15thNight
43%5%9%26%15%
1892
16th to endNight
38%28%29%19%
1913
October1st to 15thNight
45%410%23%14%1
1948
16th to endNight
50%5%10%22%10%
2175
November1st to 15thNight
51%5%14%18%8%
2334
16th to endNight
55%6%13%16%7%
2520
December1st to 15thNight
65%5%10%15%3
2547
16th to endNight
69%49%11%5%
2880

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
20%13%36%28%1
60
16th to endDay
27%11%39%17%2
178
February1st to 15thDay
26%14%35%17%5%
236
16th to endDay
20%10%32%28%8%
228
March1st to 15thDay
22%15%34%21%5%
270
16th to endDay
23%10%31%23%9%1
288
April1st to 15thDay
26%8%30%24%9%
270
16th to endDay
26%228%30%9%2
270
May1st to 15thDay
35%221%28%10%2
288
16th to endDay
33%117%30%15%1
497
June1st to 15thDay
28%314%35%16%1
495
16th to endDay
34%12%31%18%2
495
July1st to 15thDay
28%19%34%22%4
471
16th to endDay
23%111%35%25%2
326
August1st to 15thDay
23%9%35%26%4
313
16th to endDay
20%210%32%28%5%
332
September1st to 15thDay
24%114%34%22%2
315
16th to endDay
21%115%33%21%6%
287
October1st to 15thDay
23%8%22%25%15%4
230
16th to endDay
24%12%30%25%7%
240
November1st to 15thDay
28%7%28%23%8%3
235
16th to endDay
28%13%29%18%8%1
240
December1st to 15thDay
35%10%34%15%3
210
16th to endDay
35%14%34%14%1
64
January1st to 15thNight
26%17%32%17%4
734
16th to endNight
25%19%33%17%3
768
February1st to 15thNight
26%17%34%18%3
704
16th to endNight
22%17%31%21%5%1
631
March1st to 15thNight
26%12%31%24%4
720
16th to endNight
22%12%29%24%9%1
768
April1st to 15thNight
27%6%31%24%9%
620
16th to endNight
27%327%29%10%1
540
May1st to 15thNight
30%221%31%11%2
540
16th to endNight
29%218%32%14%2
552
June1st to 15thNight
35%314%30%15%1
360
16th to endNight
31%110%33%19%2
360
July1st to 15thNight
28%18%34%25%2
340
16th to endNight
29%28%35%23%1
475
August1st to 15thNight
23%18%34%28%3
539
16th to endNight
22%10%36%25%4
573
September1st to 15thNight
22%117%36%19%3
641
16th to endNight
20%221%29%20%5%
693
October1st to 15thNight
23%5%25%28%14%2
660
16th to endNight
28%9%29%23%7%
704
November1st to 15thNight
24%8%28%24%10%1
709
16th to endNight
25%13%30%20%10%
750
December1st to 15thNight
34%14%30%16%3
750
16th to endNight
35%17%29%14%2
800
Page generated at 2017-09-25 10:02:24. Version ac04

Copyright 2017 A. Danko


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