Bangor
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bangor clear sky chart from 2005-11-05 to 2017-08-12.

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
26%
14683
15%
46462
6%
14649
36%
14649
17%
31784

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
18%
720
16%
2506
5%
716
33%
716
14%
1661
January16th to endNight
15%
768
15%
2673
3%
768
31%
768
13%
1810
February1st to 15thNight
15%
704
13%
2283
4%
701
28%
701
13%
1610
February16th to endNight
18%
631
16%
1893
4%
631
32%
631
15%
1332
March1st to 15thNight
16%
720
16%
2094
5%
720
28%
720
15%
1513
March16th to endNight
23%
768
18%
2112
6%
768
33%
768
19%
1469
April1st to 15thNight
18%
670
16%
1758
4%
670
26%
670
16%
1291
April16th to endNight
23%
540
13%
1620
5%
540
29%
540
17%
1151
May1st to 15thNight
24%
540
13%
1620
7%
540
31%
540
16%
1169
May16th to endNight
25%
450
11%
1506
6%
449
33%
449
13%
1115
June1st to 15thNight
27%
360
8%
1260
5%
360
33%
360
14%
932
June16th to endNight
41%
360
8%
1260
9%
360
44%
360
19%
867
July1st to 15thNight
41%
340
9%
1295
11%
340
47%
340
18%
848
July16th to endNight
43%
384
10%
1426
10%
362
49%
362
17%
940
August1st to 15thNight
43%
528
11%
1575
7%
524
46%
524
22%
1063
August16th to endNight
43%
525
18%
1575
11%
525
47%
525
28%
981
September1st to 15thNight
39%
660
17%
1759
9%
660
44%
660
31%
1130
September16th to endNight
42%
657
27%
1815
14%
657
52%
657
33%
1085
October1st to 15thNight
31%
660
19%
1901
8%
660
43%
660
22%
1274
October16th to endNight
22%
704
16%
2241
6%
704
32%
704
18%
1531
November1st to 15thNight
29%
700
19%
2277
9%
700
42%
700
19%
1517
November16th to endNight
25%
745
17%
2487
7%
745
38%
745
15%
1672
December1st to 15thNight
17%
750
14%
2652
4%
750
30%
750
14%
1835
December16th to endNight
15%
799
15%
2874
4%
799
30%
799
12%
1988

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
19%7%35%5%34446%35%
47504
Night
18%7%35%5%24446%36%
46633
TransparencyDay
48%5%11%20%12%1
47193
Night
47%5%11%20%11%1
46462
SeeingDay
25%13%30%19%8%2
6275
Night
23%12%32%24%6%
14683

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
16%9%45%433436%38%
1432
16th to endDay
16%9%36%42435%6%36%
1549
February1st to 15thDay
14%12%47%425%437%33%
1578
16th to endDay
14%11%37%8%34445%31%
1580
March1st to 15thDay
21%10%35%42433434%
1856
16th to endDay
17%9%35%424435%38%
2112
April1st to 15thDay
21%8%36%423435%34%
2188
16th to endDay
22%7%24423345%36%
2340
May1st to 15thDay
25%7%25%5%34447%30%
2332
16th to endDay
24%7%35%434446%32%
2617
June1st to 15thDay
27%7%36%5%24446%26%
2700
16th to endDay
22%6%25%5%35%5%5%7%29%
2700
July1st to 15thDay
14%5%25%435%46%7%38%
2583
16th to endDay
16%5%35%6%45%5%6%8%33%
2633
August1st to 15thDay
16%6%245%345%6%8%35%
2288
16th to endDay
13%42443445%7%44%
2272
September1st to 15thDay
14%5%25%5%24345%46%
1870
16th to endDay
15%423323246%50%
1815
October1st to 15thDay
20%6%25%433346%40%
1728
16th to endDay
22%7%25%423345%36%
1628
November1st to 15thDay
21%6%244235%5%6%37%
1581
16th to endDay
22%6%24423435%38%
1470
December1st to 15thDay
24%9%24424335%33%
1305
16th to endDay
24%10%35%33333432%
1347
January1st to 15thNight
15%9%35%5%34446%36%
2506
16th to endNight
14%9%46%5%35%5%5%6%34%
2673
February1st to 15thNight
13%10%47%6%45%45%6%31%
2282
16th to endNight
15%11%45%6%35%24435%
1893
March1st to 15thNight
19%12%35%5%2343434%
2081
16th to endNight
17%7%36%42445%6%38%
2112
April1st to 15thNight
21%8%36%5%23436%33%
1758
16th to endNight
23%6%245%2445%5%33%
1620
May1st to 15thNight
24%6%25%5%25%46%7%29%
1620
16th to endNight
21%6%37%6%35%46%7%27%
1504
June1st to 15thNight
25%7%35%42445%8%25%
1260
16th to endNight
20%5%25%5%2446%9%34%
1260
July1st to 15thNight
13%5%36%5%35%46%9%35%
1374
16th to endNight
15%6%35%5%25%6%6%7%34%
1522
August1st to 15thNight
13%5%16%6%445%5%7%38%
1587
16th to endNight
12%415%42445%8%46%
1575
September1st to 15thNight
15%6%2431235%6%48%
1759
16th to endNight
14%313323446%52%
1815
October1st to 15thNight
19%5%24434446%40%
1901
16th to endNight
22%7%26%423336%37%
2241
November1st to 15thNight
19%7%24434345%39%
2277
16th to endNight
20%6%244245%5%6%37%
2487
December1st to 15thNight
23%8%34324445%34%
2652
16th to endNight
24%9%35%423336%32%
2874

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
46%5%12%20%11%2
1433
16th to endDay
47%5%13%21%10%1
1549
February1st to 15thDay
50%5%12%19%10%1
1581
16th to endDay
53%410%18%10%2
1580
March1st to 15thDay
53%310%17%12%2
1866
16th to endDay
48%49%17%16%3
2112
April1st to 15thDay
51%47%18%15%2
2188
16th to endDay
50%49%18%12%4
2340
May1st to 15thDay
53%5%8%17%11%2
2332
16th to endDay
52%6%11%18%9%1
2621
June1st to 15thDay
58%5%11%15%8%1
2700
16th to endDay
52%8%9%17%11%
2700
July1st to 15thDay
40%8%14%24%10%
2433
16th to endDay
46%8%14%20%9%1
2467
August1st to 15thDay
44%8%14%23%7%
2275
16th to endDay
37%7%13%24%15%
2272
September1st to 15thDay
39%5%11%25%16%1
1870
16th to endDay
34%410%29%19%1
1815
October1st to 15thDay
45%5%10%24%13%
1728
16th to endDay
48%411%23%10%
1628
November1st to 15thDay
46%5%14%18%13%1
1581
16th to endDay
48%5%15%18%12%
1470
December1st to 15thDay
51%5%13%20%8%
1305
16th to endDay
55%5%9%18%10%
1347
January1st to 15thNight
46%5%13%21%11%1
2506
16th to endNight
49%5%11%21%11%1
2673
February1st to 15thNight
51%6%12%18%10%
2283
16th to endNight
51%49%19%12%2
1893
March1st to 15thNight
53%48%19%11%2
2094
16th to endNight
46%410%18%16%2
2112
April1st to 15thNight
53%39%15%15%2
1758
16th to endNight
50%5%10%16%13%3
1620
May1st to 15thNight
52%6%10%15%14%1
1620
16th to endNight
54%7%10%17%8%
1506
June1st to 15thNight
55%7%14%15%6%1
1260
16th to endNight
46%8%14%19%9%
1260
July1st to 15thNight
44%8%15%20%11%
1295
16th to endNight
46%7%15%22%6%1
1426
August1st to 15thNight
43%8%17%21%9%
1575
16th to endNight
36%7%15%26%12%
1575
September1st to 15thNight
37%6%13%29%13%
1759
16th to endNight
32%5%9%32%18%
1815
October1st to 15thNight
45%411%24%13%1
1901
16th to endNight
49%410%23%10%
2241
November1st to 15thNight
46%413%20%12%1
2277
16th to endNight
46%6%12%19%13%1
2487
December1st to 15thNight
51%5%11%21%9%
2652
16th to endNight
52%410%20%11%
2874

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
28%11%36%21%1
60
16th to endDay
22%14%45%15%2
77
February1st to 15thDay
23%22%30%18%4
237
16th to endDay
20%20%33%20%3
239
March1st to 15thDay
31%18%31%13%4
270
16th to endDay
29%17%29%13%6%3
288
April1st to 15thDay
32%19%27%12%5%2
270
16th to endDay
28%19%30%13%5%2
270
May1st to 15thDay
33%13%31%15%41
288
16th to endDay
28%12%34%17%6%
396
June1st to 15thDay
31%10%27%21%8%
495
16th to endDay
25%10%31%23%8%
495
July1st to 15thDay
19%9%34%22%12%1
367
16th to endDay
17%8%37%22%10%3
326
August1st to 15thDay
18%8%28%30%12%2
297
16th to endDay
17%5%28%28%13%5%
268
September1st to 15thDay
19%8%27%28%11%4
255
16th to endDay
18%9%33%16%12%9%
254
October1st to 15thDay
23%16%22%16%15%5%
239
16th to endDay
29%17%28%17%5%1
240
November1st to 15thDay
25%13%26%21%9%2
235
16th to endDay
28%18%25%19%8%
240
December1st to 15thDay
33%15%33%13%4
105
16th to endDay
42%17%31%9%
64
January1st to 15thNight
21%19%35%19%3
720
16th to endNight
22%18%36%19%3
768
February1st to 15thNight
19%19%38%20%2
704
16th to endNight
23%17%35%19%3
631
March1st to 15thNight
29%15%33%18%3
720
16th to endNight
22%18%31%20%6%
768
April1st to 15thNight
25%19%32%19%2
670
16th to endNight
26%11%34%21%5%
540
May1st to 15thNight
26%10%33%24%4
540
16th to endNight
23%11%33%26%5%
450
June1st to 15thNight
28%6%32%26%6%
360
16th to endNight
24%228%37%7%
360
July1st to 15thNight
16%234%34%11%
340
16th to endNight
19%228%38%10%
384
August1st to 15thNight
15%427%40%10%
528
16th to endNight
14%430%35%12%
525
September1st to 15thNight
19%5%31%30%11%1
660
16th to endNight
14%8%30%29%14%2
657
October1st to 15thNight
24%9%29%24%10%1
660
16th to endNight
24%14%34%19%5%
704
November1st to 15thNight
23%11%30%25%8%1
700
16th to endNight
23%16%29%22%7%
745
December1st to 15thNight
29%12%36%18%3
750
16th to endNight
30%18%30%17%2
799
Page generated at 2017-08-13 14:16:36. Version ac04

Copyright 2017 A. Danko


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