Eastport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eastport clear sky chart from 2005-11-05 to 2017-12-02.

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%
15197
14%
47723
7%
15158
38%
15158
17%
33652

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%
734
13%
2589
3%
730
30%
730
12%
1847
January16th to endNight
14%
768
12%
2592
2%
768
26%
768
11%
1876
February1st to 15thNight
15%
704
9%
2286
2%
701
25%
701
12%
1709
February16th to endNight
22%
631
13%
1949
3%
631
34%
631
14%
1405
March1st to 15thNight
21%
720
15%
2046
5%
720
32%
720
16%
1529
March16th to endNight
27%
768
17%
2112
8%
768
35%
768
19%
1491
April1st to 15thNight
26%
623
15%
1779
5%
623
35%
623
18%
1309
April16th to endNight
32%
540
15%
1620
8%
540
38%
540
21%
1137
May1st to 15thNight
33%
540
13%
1620
7%
540
38%
540
18%
1191
May16th to endNight
38%
532
11%
1490
9%
532
42%
532
18%
1113
June1st to 15thNight
38%
360
8%
1260
8%
360
41%
360
14%
927
June16th to endNight
40%
360
8%
1260
9%
360
42%
360
16%
915
July1st to 15thNight
50%
340
9%
1192
12%
340
51%
340
18%
812
July16th to endNight
45%
457
9%
1493
8%
429
48%
429
16%
1066
August1st to 15thNight
53%
539
11%
1608
11%
535
54%
535
22%
1124
August16th to endNight
54%
573
19%
1719
13%
573
57%
573
27%
1109
September1st to 15thNight
49%
645
16%
1890
12%
645
53%
645
27%
1224
September16th to endNight
48%
717
26%
1980
17%
717
55%
717
34%
1208
October1st to 15thNight
39%
720
20%
2121
11%
720
47%
720
25%
1382
October16th to endNight
28%
768
17%
2382
7%
768
38%
768
20%
1624
November1st to 15thNight
30%
774
15%
2532
8%
774
39%
774
19%
1710
November16th to endNight
25%
825
15%
2730
6%
825
36%
825
15%
1879
December1st to 15thNight
14%
759
12%
2593
2%
759
25%
759
12%
1926
December16th to endNight
12%
800
10%
2880
2%
800
22%
800
10%
2139

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%35%
48721
Night
20%8%35%5%2445%7%32%
47892
TransparencyDay
47%5%12%21%11%1
48409
Night
52%412%19%10%
47723
SeeingDay
24%6%25%27%13%1
7017
Night
25%8%27%26%10%1
15198

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
17%9%46%5%246%5%8%28%
1346
16th to endDay
17%10%37%438%5%6%6%27%
1632
February1st to 15thDay
16%10%36%7%5%5%5%7%10%22%
1575
16th to endDay
14%9%45%5%46%35%7%32%
1521
March1st to 15thDay
19%10%46%424346%32%
1903
16th to endDay
16%8%25%424446%38%
2112
April1st to 15thDay
20%7%345%33345%37%
2168
16th to endDay
21%6%145%2435%6%37%
2340
May1st to 15thDay
24%7%26%424446%32%
2332
16th to endDay
24%7%244245%5%7%31%
2631
June1st to 15thDay
25%8%3442435%6%29%
2700
16th to endDay
23%6%35%5%345%5%8%29%
2700
July1st to 15thDay
16%5%2443445%9%38%
2696
16th to endDay
16%7%2443446%9%35%
2558
August1st to 15thDay
16%6%25%42445%8%40%
2340
16th to endDay
12%41343446%7%47%
2483
September1st to 15thDay
13%5%2332335%7%48%
2067
16th to endDay
16%423222346%50%
1980
October1st to 15thDay
17%5%245%23346%44%
1839
16th to endDay
20%5%25%424445%38%
1839
November1st to 15thDay
21%7%35%323347%37%
1654
16th to endDay
22%6%25%5%3445%5%34%
1560
December1st to 15thDay
27%8%345%2445%7%26%
1401
16th to endDay
24%10%46%5%245%5%6%24%
1344
January1st to 15thNight
17%9%36%5%3447%7%28%
2589
16th to endNight
16%11%36%5%37%6%7%6%24%
2592
February1st to 15thNight
17%10%35%6%46%6%5%6%25%
2285
16th to endNight
16%11%36%6%3445%5%31%
1949
March1st to 15thNight
20%10%45%6%35%436%30%
2034
16th to endNight
18%8%35%425%45%7%33%
2112
April1st to 15thNight
23%8%36%5%2345%6%30%
1779
16th to endNight
24%8%24424446%33%
1620
May1st to 15thNight
23%8%46%5%24345%30%
1620
16th to endNight
23%8%35%5%34447%28%
1488
June1st to 15thNight
30%8%25%42445%7%25%
1260
16th to endNight
25%9%35%5%23437%29%
1260
July1st to 15thNight
17%10%36%32447%9%30%
1262
16th to endNight
21%8%35%5%35%5%5%6%28%
1595
August1st to 15thNight
18%7%35%435%46%7%33%
1620
16th to endNight
16%5%25%4245%5%7%40%
1719
September1st to 15thNight
17%5%235%2345%7%41%
1890
16th to endNight
15%5%13313346%50%
1980
October1st to 15thNight
18%5%25%423446%42%
2121
16th to endNight
20%7%25%423436%37%
2382
November1st to 15thNight
19%6%26%434446%36%
2532
16th to endNight
20%7%25%42445%8%33%
2730
December1st to 15thNight
26%9%36%5%2445%7%25%
2593
16th to endNight
25%10%35%5%2445%7%24%
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
53%5%16%16%6%1
1347
16th to endDay
55%5%13%18%6%
1632
February1st to 15thDay
56%316%15%6%
1578
16th to endDay
49%5%15%19%7%1
1521
March1st to 15thDay
53%311%18%10%2
1914
16th to endDay
45%49%21%16%2
2112
April1st to 15thDay
49%38%20%15%2
2168
16th to endDay
45%5%10%20%15%3
2340
May1st to 15thDay
53%48%19%12%1
2332
16th to endDay
51%5%12%22%7%1
2635
June1st to 15thDay
54%5%12%17%9%1
2700
16th to endDay
51%6%11%18%11%
2700
July1st to 15thDay
41%7%16%23%10%
2537
16th to endDay
44%7%16%22%8%
2399
August1st to 15thDay
42%6%14%25%10%
2327
16th to endDay
35%6%15%28%14%
2483
September1st to 15thDay
35%5%13%26%17%1
2067
16th to endDay
35%49%31%17%1
1980
October1st to 15thDay
41%5%11%28%13%
1839
16th to endDay
46%5%12%25%10%
1839
November1st to 15thDay
47%5%14%19%11%
1654
16th to endDay
50%5%14%18%10%1
1560
December1st to 15thDay
57%5%16%14%5%
1401
16th to endDay
59%5%12%14%7%
1344
January1st to 15thNight
54%413%18%7%1
2589
16th to endNight
57%314%17%6%
2592
February1st to 15thNight
58%414%14%6%
2286
16th to endNight
54%411%16%11%1
1949
March1st to 15thNight
56%39%17%11%1
2046
16th to endNight
50%39%20%14%1
2112
April1st to 15thNight
55%38%15%13%2
1779
16th to endNight
51%310%17%14%2
1620
May1st to 15thNight
55%49%16%12%1
1620
16th to endNight
55%5%11%19%8%
1490
June1st to 15thNight
58%412%16%5%1
1260
16th to endNight
56%410%18%9%
1260
July1st to 15thNight
49%6%13%17%12%
1192
16th to endNight
53%5%13%17%7%1
1493
August1st to 15thNight
47%6%14%21%9%
1608
16th to endNight
42%413%27%12%
1719
September1st to 15thNight
41%411%24%16%
1890
16th to endNight
36%310%29%19%
1980
October1st to 15thNight
42%410%25%14%1
2121
16th to endNight
47%411%24%11%
2382
November1st to 15thNight
48%415%19%11%
2532
16th to endNight
50%415%18%10%
2730
December1st to 15thNight
59%413%18%5%
2593
16th to endNight
60%314%13%7%
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
16%18%36%28%
60
16th to endDay
23%10%45%16%3
160
February1st to 15thDay
21%16%35%19%6%
236
16th to endDay
19%13%34%24%7%
229
March1st to 15thDay
24%18%32%21%3
270
16th to endDay
24%11%32%21%7%1
288
April1st to 15thDay
25%10%31%22%9%1
270
16th to endDay
27%330%28%9%1
270
May1st to 15thDay
32%323%27%11%1
288
16th to endDay
31%322%26%13%2
494
June1st to 15thDay
30%122%29%13%1
495
16th to endDay
30%119%29%15%2
495
July1st to 15thDay
23%16%35%19%3
471
16th to endDay
19%119%35%22%1
326
August1st to 15thDay
21%16%35%23%1
313
16th to endDay
18%16%33%27%3
332
September1st to 15thDay
20%219%35%20%2
315
16th to endDay
18%320%31%20%5%
314
October1st to 15thDay
20%9%21%27%16%4
280
16th to endDay
22%10%32%25%8%
288
November1st to 15thDay
21%12%28%25%9%2
280
16th to endDay
23%14%32%21%6%
285
December1st to 15thDay
34%10%32%17%4
194
16th to endDay
31%15%39%10%3
64
January1st to 15thNight
23%16%34%22%3
734
16th to endNight
24%16%38%17%3
768
February1st to 15thNight
25%15%38%17%3
704
16th to endNight
23%16%30%23%41
631
March1st to 15thNight
25%11%34%24%4
720
16th to endNight
22%13%30%25%7%1
768
April1st to 15thNight
29%5%31%25%8%
623
16th to endNight
27%230%29%9%
540
May1st to 15thNight
27%325%29%11%2
540
16th to endNight
26%223%33%11%2
533
June1st to 15thNight
36%114%33%12%1
360
16th to endNight
31%114%34%17%1
360
July1st to 15thNight
23%15%38%21%
340
16th to endNight
24%114%37%20%1
457
August1st to 15thNight
20%113%38%24%2
539
16th to endNight
20%14%37%24%2
573
September1st to 15thNight
20%119%36%18%3
645
16th to endNight
17%223%32%18%3
717
October1st to 15thNight
22%425%30%14%3
720
16th to endNight
25%12%30%22%9%
768
November1st to 15thNight
23%9%30%25%10%1
774
16th to endNight
24%13%31%21%8%
825
December1st to 15thNight
33%11%34%15%4
759
16th to endNight
31%15%35%15%2
800
Page generated at 2017-12-03 11:16:47. Version ac04

Copyright 2017 A. Danko


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