Bar Harbor
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bar Harbor clear sky chart from 2005-11-05 to 2017-10-16.

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%
14980
14%
47133
7%
14944
38%
14944
17%
32998

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%
721
13%
2509
4%
717
27%
717
11%
1737
January16th to endNight
12%
768
12%
2634
2%
768
26%
768
10%
1872
February1st to 15thNight
14%
704
10%
2286
2%
701
24%
701
11%
1680
February16th to endNight
19%
631
15%
1901
4%
631
33%
631
15%
1350
March1st to 15thNight
20%
720
14%
2076
5%
720
30%
720
15%
1509
March16th to endNight
26%
768
18%
2112
8%
768
34%
768
20%
1490
April1st to 15thNight
23%
659
16%
1773
5%
659
30%
659
19%
1288
April16th to endNight
33%
540
13%
1620
6%
540
38%
540
19%
1153
May1st to 15thNight
33%
540
12%
1620
9%
540
38%
540
18%
1188
May16th to endNight
36%
492
11%
1534
10%
492
40%
492
16%
1146
June1st to 15thNight
37%
360
8%
1260
10%
360
40%
360
12%
962
June16th to endNight
45%
360
8%
1260
9%
360
48%
360
16%
902
July1st to 15thNight
50%
340
9%
1283
13%
340
52%
340
16%
859
July16th to endNight
43%
421
9%
1460
11%
396
46%
396
14%
1056
August1st to 15thNight
52%
539
11%
1608
9%
535
53%
535
20%
1141
August16th to endNight
54%
573
17%
1719
11%
573
56%
573
26%
1124
September1st to 15thNight
50%
702
16%
1918
10%
702
54%
702
30%
1247
September16th to endNight
48%
717
25%
1980
16%
717
54%
717
35%
1207
October1st to 15thNight
38%
720
19%
2088
10%
720
46%
720
24%
1384
October16th to endNight
24%
708
17%
2226
6%
708
36%
708
19%
1500
November1st to 15thNight
34%
700
17%
2277
11%
700
43%
700
18%
1527
November16th to endNight
23%
747
14%
2502
5%
747
35%
747
14%
1735
December1st to 15thNight
16%
750
12%
2607
3%
750
27%
750
12%
1878
December16th to endNight
14%
800
12%
2880
2%
800
26%
800
11%
2063

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%25%42445%7%37%
48278
Night
20%8%35%42445%6%35%
47307
TransparencyDay
47%6%13%20%11%1
47970
Night
49%6%12%19%11%1
47133
SeeingDay
24%8%27%26%11%1
6633
Night
24%10%27%25%9%1
14981

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%8%35%42435%8%36%
1426
16th to endDay
17%9%35%42425%8%36%
1587
February1st to 15thDay
16%10%36%5%35%5%5%7%30%
1575
16th to endDay
13%8%46%6%35%45%7%33%
1569
March1st to 15thDay
20%8%36%325%346%34%
1873
16th to endDay
17%7%25%32435%6%40%
2112
April1st to 15thDay
20%8%25%423346%37%
2174
16th to endDay
19%7%345%2445%6%36%
2340
May1st to 15thDay
23%8%35%5%33446%31%
2332
16th to endDay
23%7%34424347%33%
2587
June1st to 15thDay
25%8%35%5%24346%28%
2700
16th to endDay
23%7%25%423446%32%
2700
July1st to 15thDay
17%5%23425%45%9%39%
2597
16th to endDay
16%7%25%4245%6%8%36%
2597
August1st to 15thDay
16%6%25%43435%8%39%
2340
16th to endDay
12%5%145%2445%7%47%
2483
September1st to 15thDay
13%42433345%7%47%
2040
16th to endDay
15%5%24313345%50%
1980
October1st to 15thDay
18%6%25%423446%43%
1872
16th to endDay
21%7%24423445%39%
1663
November1st to 15thDay
23%5%25%323445%38%
1581
16th to endDay
20%8%35%5%13445%36%
1456
December1st to 15thDay
25%9%25%33425%7%31%
1350
16th to endDay
26%8%45%323346%32%
1344
January1st to 15thNight
17%9%35%42345%8%34%
2509
16th to endNight
16%10%45%5%3447%8%29%
2634
February1st to 15thNight
16%9%46%5%36%46%7%31%
2285
16th to endNight
16%10%345%34347%35%
1901
March1st to 15thNight
20%11%36%433346%32%
2064
16th to endNight
18%7%26%423345%38%
2112
April1st to 15thNight
22%9%35%423347%31%
1773
16th to endNight
23%8%36%423346%33%
1620
May1st to 15thNight
23%8%26%5%24346%31%
1620
16th to endNight
25%9%36%424346%29%
1532
June1st to 15thNight
30%9%244245%48%23%
1260
16th to endNight
25%7%25%43435%6%31%
1260
July1st to 15thNight
20%8%25%42445%7%33%
1361
16th to endNight
21%9%345%35%5%47%29%
1559
August1st to 15thNight
19%7%25%5%245%6%8%33%
1620
16th to endNight
15%6%2442445%9%40%
1719
September1st to 15thNight
17%5%14324446%45%
1918
16th to endNight
15%5%1331235%6%50%
1980
October1st to 15thNight
20%6%24424345%41%
2088
16th to endNight
21%7%25%423336%39%
2226
November1st to 15thNight
19%5%25%334446%39%
2277
16th to endNight
18%8%25%4245%45%37%
2502
December1st to 15thNight
25%8%245%2335%7%31%
2607
16th to endNight
24%9%25%42335%5%32%
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
48%7%15%17%9%1
1427
16th to endDay
48%6%16%19%7%1
1587
February1st to 15thDay
54%8%15%14%7%
1578
16th to endDay
49%7%13%18%9%1
1569
March1st to 15thDay
51%6%12%16%10%1
1884
16th to endDay
44%5%11%17%17%3
2112
April1st to 15thDay
46%5%10%20%15%2
2174
16th to endDay
47%5%11%17%14%3
2340
May1st to 15thDay
52%6%9%17%12%2
2332
16th to endDay
51%6%10%20%8%1
2591
June1st to 15thDay
56%5%11%16%7%1
2700
16th to endDay
52%5%10%17%12%1
2700
July1st to 15thDay
44%6%16%20%11%
2446
16th to endDay
45%7%16%20%8%
2434
August1st to 15thDay
43%6%14%24%9%
2327
16th to endDay
35%6%15%25%17%
2483
September1st to 15thDay
35%7%12%24%17%2
2040
16th to endDay
35%5%11%27%18%1
1980
October1st to 15thDay
40%5%12%25%14%1
1872
16th to endDay
46%5%13%23%10%
1663
November1st to 15thDay
47%6%12%20%12%
1581
16th to endDay
50%6%14%16%11%
1456
December1st to 15thDay
53%7%14%18%5%
1350
16th to endDay
55%5%12%17%8%
1344
January1st to 15thNight
49%7%15%19%7%
2509
16th to endNight
53%6%14%17%7%
2634
February1st to 15thNight
54%7%14%15%7%
2286
16th to endNight
50%6%11%18%11%1
1901
March1st to 15thNight
53%5%11%16%11%2
2076
16th to endNight
47%5%10%17%17%2
2112
April1st to 15thNight
52%49%15%14%2
1773
16th to endNight
52%49%17%13%3
1620
May1st to 15thNight
53%6%8%16%13%1
1620
16th to endNight
56%5%9%19%8%
1534
June1st to 15thNight
58%7%10%15%6%1
1260
16th to endNight
54%5%10%19%9%
1260
July1st to 15thNight
48%7%13%19%10%
1283
16th to endNight
54%7%12%17%7%1
1460
August1st to 15thNight
48%8%13%21%8%
1608
16th to endNight
41%6%14%21%15%
1719
September1st to 15thNight
38%6%14%24%15%1
1918
16th to endNight
35%410%28%20%
1980
October1st to 15thNight
44%410%24%14%1
2088
16th to endNight
47%411%24%11%
2226
November1st to 15thNight
46%5%13%20%12%
2277
16th to endNight
50%5%13%17%10%1
2502
December1st to 15thNight
54%6%13%18%6%
2607
16th to endNight
54%6%14%15%9%
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
18%33%31%16%
60
16th to endDay
22%25%33%13%4
115
February1st to 15thDay
22%23%34%15%3
236
16th to endDay
17%13%40%24%2
237
March1st to 15thDay
25%18%35%17%2
270
16th to endDay
25%17%30%19%6%1
288
April1st to 15thDay
28%11%32%19%6%1
270
16th to endDay
26%5%39%17%9%1
270
May1st to 15thDay
31%6%30%22%6%2
288
16th to endDay
28%5%26%27%11%
409
June1st to 15thDay
29%222%32%12%1
495
16th to endDay
30%120%33%13%1
495
July1st to 15thDay
22%322%30%18%1
380
16th to endDay
23%119%35%17%2
326
August1st to 15thDay
20%219%34%20%1
313
16th to endDay
18%220%32%21%4
332
September1st to 15thDay
21%225%33%15%2
315
16th to endDay
19%326%29%15%6%
314
October1st to 15thDay
22%9%22%29%14%2
288
16th to endDay
25%11%36%21%4
243
November1st to 15thDay
25%16%22%24%8%2
235
16th to endDay
23%20%30%17%7%1
240
December1st to 15thDay
31%15%32%17%3
150
16th to endDay
37%18%29%14%
64
January1st to 15thNight
22%22%34%16%3
721
16th to endNight
23%22%36%14%2
768
February1st to 15thNight
22%21%38%14%2
704
16th to endNight
22%19%33%20%3
631
March1st to 15thNight
26%15%32%21%4
720
16th to endNight
21%14%31%23%7%
768
April1st to 15thNight
28%8%35%21%6%
659
16th to endNight
28%5%26%30%8%1
540
May1st to 15thNight
28%128%30%9%1
540
16th to endNight
29%420%31%12%1
493
June1st to 15thNight
36%314%29%14%1
360
16th to endNight
29%17%35%15%1
360
July1st to 15thNight
25%114%39%18%
340
16th to endNight
27%13%36%21%
421
August1st to 15thNight
24%12%38%21%1
539
16th to endNight
19%114%37%24%2
573
September1st to 15thNight
20%120%37%18%2
702
16th to endNight
18%225%29%17%5%
717
October1st to 15thNight
24%6%24%27%14%2
720
16th to endNight
25%12%33%20%7%
708
November1st to 15thNight
22%10%27%28%10%1
700
16th to endNight
22%17%31%19%8%
747
December1st to 15thNight
31%17%30%16%3
750
16th to endNight
29%19%33%15%1
800
Page generated at 2017-10-17 16:35:20. Version ac04

Copyright 2017 A. Danko


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