The Hughesville Sky-view Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Hughesville Sky-view Observatory clear sky chart from 2005-11-05 to 2017-10-06.

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
35%
15354
21%
47107
10%
15315
47%
15315
24%
29323

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
21%
718
22%
2422
8%
716
40%
716
17%
1486
January16th to endNight
18%
768
23%
2496
7%
768
38%
768
19%
1556
February1st to 15thNight
19%
702
21%
2287
6%
701
38%
701
20%
1383
February16th to endNight
16%
631
25%
1897
5%
631
39%
631
20%
1170
March1st to 15thNight
22%
720
22%
2018
8%
720
37%
720
23%
1286
March16th to endNight
21%
768
21%
2078
7%
768
33%
768
23%
1389
April1st to 15thNight
24%
718
20%
1796
4%
718
33%
718
28%
1168
April16th to endNight
35%
720
20%
1800
7%
720
40%
720
30%
1180
May1st to 15thNight
31%
583
17%
1663
8%
583
38%
583
24%
1124
May16th to endNight
51%
374
17%
1497
15%
374
59%
374
23%
870
June1st to 15thNight
54%
360
19%
1440
18%
360
62%
360
25%
818
June16th to endNight
56%
360
16%
1440
16%
360
61%
360
24%
827
July1st to 15thNight
52%
340
13%
1360
14%
340
55%
340
19%
846
July16th to endNight
64%
544
16%
1575
11%
511
70%
511
33%
914
August1st to 15thNight
63%
551
17%
1621
12%
548
65%
548
29%
1026
August16th to endNight
58%
764
19%
1910
11%
764
59%
764
31%
1278
September1st to 15thNight
57%
720
25%
1800
14%
720
61%
720
34%
1173
September16th to endNight
51%
717
22%
1966
16%
717
56%
717
30%
1272
October1st to 15thNight
45%
684
24%
2051
19%
684
54%
684
27%
1290
October16th to endNight
35%
704
29%
2112
16%
704
52%
704
29%
1233
November1st to 15thNight
34%
700
24%
2230
13%
700
50%
700
26%
1322
November16th to endNight
31%
720
23%
2440
12%
720
46%
720
22%
1440
December1st to 15thNight
25%
720
20%
2520
8%
720
41%
720
17%
1574
December16th to endNight
19%
768
22%
2688
7%
768
39%
768
17%
1698

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
13%5%2443445%7%42%
48077
Night
14%5%2442445%7%44%
47289
Cloud CoverDay
13%5%2443445%7%42%
48087
Night
13%5%2442445%7%44%
47293
TransparencyDay
39%6%11%23%16%3
47777
Night
38%5%11%23%17%3
47107
SeeingDay
16%12%28%24%13%5%
5801
Night
17%13%28%26%12%1
15359

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
15%7%2443336%5%42%
1515
16th to endDay
15%6%35%5%33346%42%
1728
February1st to 15thDay
15%6%244345%5%5%42%
1575
16th to endDay
13%7%345%34445%42%
1575
March1st to 15thDay
15%7%245%23436%45%
1930
16th to endDay
16%7%24424346%42%
2145
April1st to 15thDay
13%5%24424348%46%
2152
16th to endDay
15%5%24424436%45%
2160
May1st to 15thDay
16%5%244345%5%8%39%
2295
16th to endDay
13%4245%25%5%5%9%40%
2618
June1st to 15thDay
12%3245%35%5%6%9%42%
2520
16th to endDay
8%3245%36%6%7%10%41%
2520
July1st to 15thDay
9%5%25%5%35%5%7%10%39%
2520
16th to endDay
6%325%6%36%6%8%10%39%
2483
August1st to 15thDay
11%6%26%5%36%6%6%9%35%
2314
16th to endDay
10%425%5%346%6%8%40%
2292
September1st to 15thDay
12%42442445%8%45%
2160
16th to endDay
14%7%25%4345%5%6%39%
1989
October1st to 15thDay
17%413423446%46%
1707
16th to endDay
14%5%24423345%50%
1760
November1st to 15thDay
16%413423346%50%
1625
16th to endDay
14%5%24324436%47%
1518
December1st to 15thDay
15%5%2442445%6%43%
1440
16th to endDay
18%7%25%5%13446%40%
1536
January1st to 15thNight
15%6%24424347%43%
2422
16th to endNight
16%6%34423445%45%
2496
February1st to 15thNight
14%6%15%324446%46%
2285
16th to endNight
14%6%24323337%46%
1897
March1st to 15thNight
15%5%1443445%6%44%
2006
16th to endNight
16%5%35%423437%42%
2078
April1st to 15thNight
14%4145%3445%7%45%
1796
16th to endNight
17%5%23323447%45%
1800
May1st to 15thNight
15%5%45%42445%7%39%
1663
16th to endNight
13%41442346%10%41%
1495
June1st to 15thNight
10%43442347%10%42%
1440
16th to endNight
8%425%5%345%7%11%40%
1440
July1st to 15thNight
7%5%36%7%35%5%6%9%37%
1440
16th to endNight
6%3145%36%47%13%43%
1682
August1st to 15thNight
8%5%15%5%35%6%6%9%42%
1632
16th to endNight
10%5%35%5%25%45%9%40%
1910
September1st to 15thNight
12%4245%3445%8%45%
1800
16th to endNight
13%6%235%34447%43%
1966
October1st to 15thNight
16%425%423435%46%
2051
16th to endNight
14%314323446%51%
2112
November1st to 15thNight
14%5%24313336%50%
2230
16th to endNight
15%5%2342345%7%45%
2440
December1st to 15thNight
17%5%245%25%45%6%40%
2520
16th to endNight
17%6%24424346%42%
2688

Percentage Cloud Cover SE (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
15%6%25%43336%5%42%
1515
16th to endDay
15%6%36%423347%42%
1728
February1st to 15thDay
14%7%344345%45%42%
1575
16th to endDay
13%7%35%5%34345%42%
1575
March1st to 15thDay
15%6%25%423336%45%
1941
16th to endDay
17%6%25%5%24345%42%
2144
April1st to 15thDay
13%5%2342435%7%46%
2152
16th to endDay
15%5%24433436%45%
2160
May1st to 15thDay
16%5%25%4245%5%8%39%
2295
16th to endDay
13%4245%25%5%5%9%41%
2618
June1st to 15thDay
11%3244345%7%9%42%
2520
16th to endDay
8%3245%36%6%7%10%42%
2520
July1st to 15thDay
9%5%245%35%5%6%10%40%
2520
16th to endDay
6%325%5%46%7%8%11%39%
2483
August1st to 15thDay
10%6%26%5%35%6%7%9%35%
2314
16th to endDay
10%5%245%35%5%6%9%40%
2292
September1st to 15thDay
12%424424449%45%
2160
16th to endDay
14%7%245%25%45%7%38%
1989
October1st to 15thDay
18%413324346%46%
1707
16th to endDay
14%424333445%49%
1760
November1st to 15thDay
16%413422346%49%
1625
16th to endDay
14%5%24323445%47%
1518
December1st to 15thDay
15%5%2432445%6%43%
1440
16th to endDay
18%7%26%413445%41%
1536
January1st to 15thNight
15%6%3442435%6%43%
2422
16th to endNight
16%6%34423435%45%
2496
February1st to 15thNight
14%6%25%324436%46%
2278
16th to endNight
14%6%24324346%47%
1897
March1st to 15thNight
15%5%3442345%6%44%
2018
16th to endNight
16%5%24423446%42%
2078
April1st to 15thNight
14%5%14424446%46%
1796
16th to endNight
17%423323347%45%
1800
May1st to 15thNight
15%6%36%42445%7%39%
1662
16th to endNight
12%4244245%6%10%41%
1495
June1st to 15thNight
10%4344245%7%11%42%
1440
16th to endNight
8%425%435%5%7%11%40%
1440
July1st to 15thNight
7%6%36%6%45%5%7%10%37%
1440
16th to endNight
6%3245%45%5%7%12%42%
1682
August1st to 15thNight
9%4245%36%5%5%8%43%
1632
16th to endNight
10%426%5%35%5%5%9%41%
1910
September1st to 15thNight
11%5%2343445%8%45%
1800
16th to endNight
13%6%2443346%7%42%
1966
October1st to 15thNight
15%415%423446%45%
2051
16th to endNight
14%414323346%51%
2112
November1st to 15thNight
14%5%24323235%50%
2230
16th to endNight
14%5%234235%5%6%45%
2440
December1st to 15thNight
16%6%25%424446%40%
2520
16th to endNight
17%6%25%433346%42%
2688

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
41%5%11%23%14%3
1516
16th to endDay
42%311%23%15%3
1728
February1st to 15thDay
42%49%25%14%2
1577
16th to endDay
43%410%24%16%1
1575
March1st to 15thDay
40%49%24%16%4
1941
16th to endDay
43%410%20%17%3
2145
April1st to 15thDay
36%5%9%25%18%4
2152
16th to endDay
39%5%9%19%19%7%
2160
May1st to 15thDay
41%7%12%21%15%1
2295
16th to endDay
38%7%14%25%13%1
2622
June1st to 15thDay
35%7%13%28%13%
2520
16th to endDay
34%9%15%21%16%2
2520
July1st to 15thDay
37%8%14%22%15%3
2371
16th to endDay
33%9%15%23%15%1
2327
August1st to 15thDay
40%8%12%22%14%
2301
16th to endDay
37%7%13%22%15%3
2292
September1st to 15thDay
36%5%13%21%19%3
2160
16th to endDay
43%5%8%22%18%2
1989
October1st to 15thDay
37%5%7%27%17%3
1707
16th to endDay
36%38%26%20%3
1760
November1st to 15thDay
35%411%24%19%5%
1625
16th to endDay
37%410%25%19%3
1518
December1st to 15thDay
39%5%13%23%13%4
1440
16th to endDay
44%410%23%14%1
1536
January1st to 15thNight
41%410%20%18%4
2422
16th to endNight
42%39%25%17%1
2496
February1st to 15thNight
39%39%26%18%3
2287
16th to endNight
38%39%25%19%2
1897
March1st to 15thNight
39%410%27%15%2
2018
16th to endNight
42%5%10%21%18%2
2078
April1st to 15thNight
38%410%21%22%3
1796
16th to endNight
37%5%10%21%17%6%
1800
May1st to 15thNight
43%6%12%21%13%2
1663
16th to endNight
35%7%17%22%14%1
1497
June1st to 15thNight
34%7%12%27%16%1
1440
16th to endNight
36%7%16%18%18%2
1440
July1st to 15thNight
41%8%16%18%12%3
1360
16th to endNight
30%8%17%26%16%1
1575
August1st to 15thNight
35%8%14%22%17%1
1621
16th to endNight
38%6%12%23%16%2
1910
September1st to 15thNight
36%6%11%21%19%4
1800
16th to endNight
39%5%10%21%20%3
1966
October1st to 15thNight
39%47%25%18%4
2051
16th to endNight
33%38%27%22%3
2112
November1st to 15thNight
37%28%22%21%7%
2230
16th to endNight
37%410%24%18%4
2440
December1st to 15thNight
42%410%23%14%3
2520
16th to endNight
43%5%11%23%14%2
2688

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
24%28%33%12%1
74
16th to endDay
20%36%32%10%
96
February1st to 15thDay
21%35%34%6%2
90
16th to endDay
18%22%41%15%1
234
March1st to 15thDay
17%24%31%21%4
270
16th to endDay
17%20%39%15%42
288
April1st to 15thDay
17%17%34%21%10%
270
16th to endDay
18%12%33%21%10%4
270
May1st to 15thDay
29%15%27%15%10%1
288
16th to endDay
20%6%24%28%14%5%
331
June1st to 15thDay
13%9%29%23%18%4
315
16th to endDay
10%8%32%33%12%3
315
July1st to 15thDay
13%325%34%18%4
305
16th to endDay
6%220%36%23%10%
326
August1st to 15thDay
15%418%33%19%8%
313
16th to endDay
9%217%35%20%15%
332
September1st to 15thDay
13%7%25%22%15%15%
315
16th to endDay
23%423%22%14%11%
314
October1st to 15thDay
19%7%24%22%20%5%
278
16th to endDay
13%15%33%22%12%1
272
November1st to 15thDay
20%12%28%19%16%2
243
16th to endDay
17%22%28%19%10%1
138
December1st to 15thDay
18%31%20%18%10%1
60
16th to endDay
34%23%28%12%1
64
January1st to 15thNight
21%21%31%21%4
720
16th to endNight
21%21%35%19%1
768
February1st to 15thNight
18%22%36%20%1
704
16th to endNight
19%25%34%17%2
631
March1st to 15thNight
19%20%34%21%3
720
16th to endNight
19%16%39%17%5%
768
April1st to 15thNight
16%19%37%21%4
718
16th to endNight
18%11%30%27%11%
720
May1st to 15thNight
18%9%35%25%10%
583
16th to endNight
13%7%21%37%17%1
375
June1st to 15thNight
10%324%41%18%2
360
16th to endNight
8%5%21%45%18%
360
July1st to 15thNight
10%222%36%26%1
340
16th to endNight
7%216%39%29%4
544
August1st to 15thNight
11%114%44%24%2
551
16th to endNight
12%315%35%29%3
764
September1st to 15thNight
15%317%36%24%3
720
16th to endNight
18%320%29%25%3
717
October1st to 15thNight
18%9%19%28%17%5%
684
16th to endNight
17%15%29%23%13%
704
November1st to 15thNight
17%15%28%24%12%2
700
16th to endNight
17%19%28%25%8%1
720
December1st to 15thNight
22%16%31%18%10%
720
16th to endNight
21%20%35%20%3
768
Page generated at 2017-10-07 14:07:50. Version ac04

Copyright 2017 A. Danko


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