Machias
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Machias 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
24%
15190
14%
47733
6%
15151
33%
15151
15%
33637

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
13%
729
13%
2561
3%
725
25%
725
10%
1771
January16th to endNight
11%
768
11%
2609
1%
768
23%
768
10%
1846
February1st to 15thNight
13%
704
10%
2286
2%
701
23%
701
9%
1657
February16th to endNight
15%
631
15%
1931
3%
631
29%
631
12%
1366
March1st to 15thNight
16%
720
15%
2058
5%
720
26%
720
13%
1514
March16th to endNight
21%
768
17%
2112
6%
768
29%
768
16%
1505
April1st to 15thNight
17%
637
15%
1777
3%
637
27%
637
15%
1321
April16th to endNight
26%
540
13%
1620
5%
540
33%
540
17%
1152
May1st to 15thNight
23%
540
13%
1620
7%
540
30%
540
14%
1213
May16th to endNight
27%
516
10%
1502
6%
515
33%
515
14%
1131
June1st to 15thNight
27%
360
8%
1260
5%
360
32%
360
11%
959
June16th to endNight
31%
360
8%
1260
7%
360
36%
360
12%
929
July1st to 15thNight
41%
340
9%
1223
10%
340
44%
340
15%
855
July16th to endNight
35%
442
9%
1479
8%
415
41%
415
12%
1083
August1st to 15thNight
45%
539
9%
1608
8%
535
46%
535
16%
1173
August16th to endNight
47%
573
17%
1719
11%
573
51%
573
22%
1145
September1st to 15thNight
40%
666
15%
1899
9%
666
45%
666
25%
1254
September16th to endNight
38%
717
25%
1980
12%
717
48%
717
31%
1229
October1st to 15thNight
32%
720
19%
2109
9%
720
41%
720
22%
1395
October16th to endNight
23%
768
17%
2397
6%
768
34%
768
19%
1606
November1st to 15thNight
28%
768
16%
2505
9%
768
37%
768
16%
1708
November16th to endNight
18%
825
16%
2730
4%
825
32%
825
13%
1882
December1st to 15thNight
12%
759
11%
2608
3%
759
22%
759
10%
1879
December16th to endNight
11%
800
11%
2880
2%
800
23%
800
9%
2064

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%7%25%424447%36%
48713
Night
20%8%35%424446%35%
47904
TransparencyDay
49%6%12%19%10%1
48402
Night
51%5%12%19%10%
47733
SeeingDay
24%16%25%22%9%1
6929
Night
23%22%24%20%7%
15190

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%7%345%23445%39%
1376
16th to endDay
18%9%45%423345%37%
1614
February1st to 15thDay
17%10%35%5%36%448%31%
1575
16th to endDay
15%9%36%43445%8%33%
1539
March1st to 15thDay
21%10%35%424335%34%
1891
16th to endDay
18%9%35%5%33236%38%
2112
April1st to 15thDay
22%9%35%323346%34%
2170
16th to endDay
23%7%25%423346%35%
2340
May1st to 15thDay
26%8%25%5%2435%6%28%
2332
16th to endDay
25%7%3442345%7%30%
2618
June1st to 15thDay
27%7%35%5%1345%7%28%
2700
16th to endDay
24%7%35%5%34347%29%
2700
July1st to 15thDay
17%5%2443446%10%35%
2661
16th to endDay
17%7%25%4345%5%9%33%
2574
August1st to 15thDay
17%6%25%42445%8%37%
2340
16th to endDay
13%42343346%9%43%
2483
September1st to 15thDay
15%5%2332445%6%46%
2058
16th to endDay
17%414423236%48%
1980
October1st to 15thDay
18%5%24333447%41%
1851
16th to endDay
22%5%2442335%5%38%
1826
November1st to 15thDay
22%6%25%32335%7%37%
1683
16th to endDay
22%8%24314336%38%
1560
December1st to 15thDay
27%8%23423436%33%
1386
16th to endDay
27%8%25%423245%34%
1344
January1st to 15thNight
17%8%35%424346%37%
2561
16th to endNight
15%11%36%325%45%7%33%
2609
February1st to 15thNight
16%9%35%5%35%446%34%
2285
16th to endNight
17%9%35%5%24446%36%
1931
March1st to 15thNight
19%11%37%424336%33%
2046
16th to endNight
17%8%35%5%24445%36%
2112
April1st to 15thNight
25%7%35%42445%5%30%
1777
16th to endNight
23%8%35%424346%32%
1620
May1st to 15thNight
25%9%35%5%33445%30%
1620
16th to endNight
27%7%25%5%3445%5%28%
1500
June1st to 15thNight
31%9%35%424346%24%
1260
16th to endNight
26%9%35%42425%7%28%
1260
July1st to 15thNight
20%9%25%4345%6%8%31%
1296
16th to endNight
22%8%45%5%36%446%29%
1580
August1st to 15thNight
18%8%24435%5%6%8%32%
1620
16th to endNight
17%5%33424447%40%
1719
September1st to 15thNight
19%5%24323337%42%
1899
16th to endNight
14%5%1442225%6%49%
1980
October1st to 15thNight
20%424433446%40%
2109
16th to endNight
22%6%24422336%40%
2397
November1st to 15thNight
20%6%25%42445%5%38%
2505
16th to endNight
20%7%25%42445%6%37%
2730
December1st to 15thNight
25%9%35%322335%34%
2608
16th to endNight
24%8%34424435%34%
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%17%17%7%1
1377
16th to endDay
51%5%17%18%6%
1614
February1st to 15thDay
53%7%15%15%6%
1578
16th to endDay
47%7%15%19%7%1
1539
March1st to 15thDay
52%5%11%17%10%2
1902
16th to endDay
46%5%11%17%15%3
2112
April1st to 15thDay
47%5%10%18%14%2
2170
16th to endDay
48%6%10%17%14%2
2340
May1st to 15thDay
54%5%10%15%12%1
2332
16th to endDay
53%6%11%19%7%1
2622
June1st to 15thDay
57%5%11%14%8%1
2700
16th to endDay
56%5%9%17%10%1
2700
July1st to 15thDay
49%6%13%21%8%
2505
16th to endDay
51%6%14%18%7%
2413
August1st to 15thDay
49%6%12%21%9%
2327
16th to endDay
40%5%14%24%13%
2483
September1st to 15thDay
38%6%12%23%16%1
2058
16th to endDay
39%48%29%16%1
1980
October1st to 15thDay
40%5%13%25%14%
1851
16th to endDay
45%5%12%24%10%
1826
November1st to 15thDay
46%6%15%19%11%
1683
16th to endDay
49%6%14%18%9%1
1560
December1st to 15thDay
54%6%16%17%6%
1386
16th to endDay
55%5%12%17%8%
1344
January1st to 15thNight
52%415%19%7%
2561
16th to endNight
52%6%16%17%6%
2609
February1st to 15thNight
53%6%15%16%6%
2286
16th to endNight
50%6%12%18%10%1
1931
March1st to 15thNight
54%410%16%12%1
2058
16th to endNight
50%410%19%14%1
2112
April1st to 15thNight
54%5%8%15%12%2
1777
16th to endNight
52%411%15%13%2
1620
May1st to 15thNight
56%5%7%16%12%1
1620
16th to endNight
57%411%17%7%
1502
June1st to 15thNight
62%411%14%5%1
1260
16th to endNight
58%49%18%9%
1260
July1st to 15thNight
51%6%13%16%12%
1223
16th to endNight
56%6%11%16%7%1
1479
August1st to 15thNight
51%7%12%19%8%
1608
16th to endNight
44%5%13%23%12%
1719
September1st to 15thNight
42%5%11%24%15%
1899
16th to endNight
37%39%29%20%
1980
October1st to 15thNight
43%5%9%24%14%1
2109
16th to endNight
45%5%12%24%11%
2397
November1st to 15thNight
48%5%13%19%11%
2505
16th to endNight
49%6%13%18%11%
2730
December1st to 15thNight
55%414%18%6%
2608
16th to endNight
56%415%15%8%
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%23%41%16%1
60
16th to endDay
23%23%34%16%2
142
February1st to 15thDay
23%28%30%14%2
236
16th to endDay
19%24%31%20%3
232
March1st to 15thDay
22%30%28%13%4
270
16th to endDay
23%26%26%16%5%1
288
April1st to 15thDay
27%19%32%13%5%1
270
16th to endDay
24%16%34%17%5%2
270
May1st to 15thDay
30%18%23%18%5%1
288
16th to endDay
29%18%23%18%9%1
465
June1st to 15thDay
26%14%23%27%8%
495
16th to endDay
31%14%18%22%12%1
495
July1st to 15thDay
28%10%18%25%14%1
439
16th to endDay
25%11%19%28%13%1
326
August1st to 15thDay
22%7%20%32%15%2
313
16th to endDay
19%6%20%31%19%3
332
September1st to 15thDay
20%7%23%31%13%2
315
16th to endDay
20%8%21%29%15%4
314
October1st to 15thDay
19%15%24%23%13%2
283
16th to endDay
23%16%32%21%5%
288
November1st to 15thDay
20%21%24%22%8%2
280
16th to endDay
22%26%27%17%5%
285
December1st to 15thDay
30%23%27%15%2
179
16th to endDay
37%20%31%9%1
64
January1st to 15thNight
19%33%29%13%3
729
16th to endNight
20%33%29%13%2
768
February1st to 15thNight
20%33%28%14%2
704
16th to endNight
20%31%27%15%3
631
March1st to 15thNight
23%30%25%16%3
720
16th to endNight
19%29%26%18%6%
768
April1st to 15thNight
24%22%32%15%4
637
16th to endNight
22%19%25%25%6%
540
May1st to 15thNight
25%18%25%22%6%2
540
16th to endNight
26%20%20%24%7%1
516
June1st to 15thNight
29%20%16%24%8%
360
16th to endNight
28%17%14%27%10%1
360
July1st to 15thNight
28%12%11%29%16%
340
16th to endNight
27%16%11%29%14%
442
August1st to 15thNight
24%10%12%32%18%1
539
16th to endNight
20%10%14%32%19%2
573
September1st to 15thNight
21%10%20%32%14%1
666
16th to endNight
20%10%25%24%14%3
717
October1st to 15thNight
22%12%26%24%11%2
720
16th to endNight
23%18%31%18%7%
768
November1st to 15thNight
19%22%24%22%9%1
768
16th to endNight
20%29%27%14%6%
825
December1st to 15thNight
30%26%26%12%3
759
16th to endNight
29%31%25%11%1
800
Page generated at 2017-12-03 11:16:48. Version ac04

Copyright 2017 A. Danko


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