Minakakis Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Minakakis Observatory clear sky chart from 2005-11-05 to 2017-10-31.

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
32%
15015
14%
47214
8%
14978
39%
14978
19%
32779

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
12%
717
9%
2452
3%
716
20%
716
8%
1921
January16th to endNight
14%
768
12%
2496
3%
768
24%
768
10%
1927
February1st to 15thNight
13%
701
9%
2287
2%
701
21%
701
10%
1757
February16th to endNight
20%
631
12%
2009
4%
631
29%
631
12%
1495
March1st to 15thNight
20%
720
13%
1980
6%
720
27%
720
16%
1469
March16th to endNight
28%
768
20%
2112
9%
768
38%
768
22%
1462
April1st to 15thNight
25%
718
14%
1830
4%
718
31%
718
21%
1334
April16th to endNight
35%
548
20%
1628
8%
548
44%
548
25%
1058
May1st to 15thNight
43%
511
16%
1591
11%
511
50%
511
24%
1051
May16th to endNight
45%
374
17%
1497
14%
374
56%
374
25%
855
June1st to 15thNight
45%
360
13%
1440
11%
360
55%
360
20%
862
June16th to endNight
50%
360
15%
1302
15%
360
58%
360
27%
761
July1st to 15thNight
60%
340
17%
1298
21%
340
66%
340
35%
654
July16th to endNight
58%
512
15%
1543
13%
479
61%
479
31%
900
August1st to 15thNight
64%
539
17%
1609
13%
536
68%
536
36%
936
August16th to endNight
56%
615
23%
1761
14%
615
61%
615
34%
1072
September1st to 15thNight
52%
720
21%
1827
10%
720
57%
720
35%
1173
September16th to endNight
55%
717
23%
1992
16%
717
59%
717
32%
1240
October1st to 15thNight
38%
720
18%
2160
14%
720
44%
720
22%
1453
October16th to endNight
23%
768
14%
2303
7%
768
31%
768
15%
1699
November1st to 15thNight
32%
700
17%
2369
14%
700
38%
700
19%
1585
November16th to endNight
24%
720
10%
2520
6%
720
30%
720
11%
1879
December1st to 15thNight
14%
720
7%
2520
2%
720
19%
720
9%
2008
December16th to endNight
11%
768
5%
2688
1%
768
16%
768
6%
2228

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%8%36%6%35%5%5%7%32%
48515
Night
13%7%36%5%35%45%7%36%
47395
Cloud CoverDay
13%7%36%6%35%5%5%7%33%
48525
Night
14%7%36%5%3445%6%36%
47399
TransparencyDay
49%8%13%18%9%
48215
Night
46%8%13%19%10%1
47214
SeeingDay
16%10%28%25%13%5%
5698
Night
17%12%31%26%11%1
15022

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
14%12%6%9%7%5%7%45%6%20%
1483
16th to endDay
10%15%7%10%9%5%6%5%5%5%17%
1728
February1st to 15thDay
12%13%6%10%10%45%46%6%19%
1575
16th to endDay
16%11%48%7%35%45%7%24%
1461
March1st to 15thDay
14%9%5%8%8%45%445%28%
1969
16th to endDay
12%8%5%7%6%35%45%5%34%
2112
April1st to 15thDay
17%9%45%5%35%5%46%31%
2119
16th to endDay
17%8%36%5%23346%39%
2340
May1st to 15thDay
15%5%36%6%346%5%6%35%
2358
16th to endDay
10%5%35%5%35%5%5%8%40%
2618
June1st to 15thDay
14%5%25%5%25%5%6%9%37%
2520
16th to endDay
11%425%6%36%5%6%10%36%
2652
July1st to 15thDay
7%425%6%46%6%7%9%40%
2577
16th to endDay
9%435%6%36%5%7%9%36%
2516
August1st to 15thDay
7%5%26%7%45%6%7%9%37%
2340
16th to endDay
11%5%25%6%36%5%7%8%37%
2429
September1st to 15thDay
12%6%25%6%35%45%7%39%
2130
16th to endDay
13%5%35%6%3445%8%39%
1966
October1st to 15thDay
18%7%36%6%4445%5%34%
1800
16th to endDay
21%9%37%6%45%45%5%24%
1920
November1st to 15thDay
11%9%38%6%35%47%7%31%
1486
16th to endDay
15%11%6%7%7%46%46%6%23%
1440
December1st to 15thDay
14%16%6%10%7%45%45%5%18%
1440
16th to endDay
18%13%5%9%8%47%5%5%6%14%
1536
January1st to 15thNight
18%11%48%7%345%5%7%22%
2452
16th to endNight
11%9%6%11%9%46%45%7%23%
2496
February1st to 15thNight
13%10%47%9%46%45%7%26%
2285
16th to endNight
11%10%5%8%7%46%45%6%28%
2009
March1st to 15thNight
17%8%46%6%25%45%7%30%
1968
16th to endNight
13%8%46%424345%41%
2112
April1st to 15thNight
16%8%345%245%5%6%35%
1830
16th to endNight
11%6%25%6%3445%5%43%
1628
May1st to 15thNight
14%5%145%345%47%41%
1591
16th to endNight
11%325%415%45%7%48%
1495
June1st to 15thNight
11%425%5%445%6%8%41%
1440
16th to endNight
8%425%42445%8%47%
1302
July1st to 15thNight
5%312325%447%58%
1377
16th to endNight
7%3244345%6%8%49%
1650
August1st to 15thNight
6%3244145%5%8%51%
1620
16th to endNight
8%4244245%5%5%52%
1761
September1st to 15thNight
10%4144245%5%7%49%
1827
16th to endNight
11%5%2443435%7%49%
1992
October1st to 15thNight
16%6%27%423446%40%
2160
16th to endNight
18%9%36%5%4445%7%30%
2303
November1st to 15thNight
14%6%35%436%46%7%36%
2369
16th to endNight
17%9%47%5%35%5%6%7%27%
2520
December1st to 15thNight
18%12%47%5%45%5%5%7%22%
2520
16th to endNight
19%12%7%10%6%35%5%6%6%16%
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%12%6%8%7%46%45%6%20%
1483
16th to endDay
11%14%6%10%8%5%7%5%45%18%
1728
February1st to 15thDay
13%13%5%9%9%46%5%5%6%20%
1575
16th to endDay
17%11%5%7%6%36%45%6%25%
1461
March1st to 15thDay
14%11%49%7%36%5%45%28%
1980
16th to endDay
13%8%47%6%35%446%34%
2111
April1st to 15thDay
17%9%45%5%35%45%6%32%
2119
16th to endDay
17%7%35%5%24436%39%
2340
May1st to 15thDay
15%6%36%5%346%5%6%35%
2358
16th to endDay
11%425%5%445%6%8%40%
2618
June1st to 15thDay
14%5%25%435%5%6%8%38%
2520
16th to endDay
11%425%5%36%5%6%11%37%
2652
July1st to 15thDay
7%4246%36%6%7%9%41%
2577
16th to endDay
9%5%25%6%36%6%6%9%37%
2516
August1st to 15thDay
8%5%26%7%45%5%7%9%37%
2340
16th to endDay
11%425%5%445%6%8%39%
2429
September1st to 15thDay
13%5%25%6%2445%8%40%
2130
16th to endDay
13%5%26%5%35%45%7%40%
1966
October1st to 15thDay
18%6%35%6%45%346%34%
1800
16th to endDay
22%8%46%7%36%5%5%5%24%
1920
November1st to 15thDay
12%9%47%6%25%46%8%32%
1486
16th to endDay
16%11%5%7%6%45%5%5%7%24%
1440
December1st to 15thDay
14%15%5%10%7%46%46%5%18%
1440
16th to endDay
19%13%6%9%7%47%45%7%15%
1536
January1st to 15thNight
18%12%5%8%6%345%5%5%23%
2452
16th to endNight
12%10%5%9%7%5%5%5%47%24%
2496
February1st to 15thNight
13%10%47%8%45%5%5%6%27%
2278
16th to endNight
12%10%48%7%36%5%5%5%29%
2009
March1st to 15thNight
18%8%36%5%35%5%5%6%31%
1980
16th to endNight
13%8%47%32444442%
2112
April1st to 15thNight
17%7%35%425%447%36%
1830
16th to endNight
11%6%26%5%3345%6%43%
1628
May1st to 15thNight
14%5%245%25%45%7%41%
1590
16th to endNight
11%42443445%7%48%
1495
June1st to 15thNight
12%425%5%445%6%8%41%
1440
16th to endNight
9%4236%2435%8%47%
1302
July1st to 15thNight
5%313325%35%7%57%
1377
16th to endNight
7%3244345%5%8%50%
1650
August1st to 15thNight
6%3143345%6%7%51%
1620
16th to endNight
8%4245%235%4453%
1761
September1st to 15thNight
11%32432445%6%49%
1827
16th to endNight
11%424324447%49%
1992
October1st to 15thNight
16%6%25%5%23346%41%
2160
16th to endNight
18%8%36%5%3445%5%32%
2303
November1st to 15thNight
15%6%25%5%35%5%5%7%37%
2369
16th to endNight
17%9%46%5%36%46%8%28%
2520
December1st to 15thNight
18%12%46%6%35%45%7%24%
2520
16th to endNight
19%12%7%10%6%35%5%5%6%16%
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
63%8%11%11%4
1484
16th to endDay
67%7%10%8%5%
1728
February1st to 15thDay
63%9%10%12%2
1577
16th to endDay
59%7%12%13%6%1
1461
March1st to 15thDay
56%8%12%14%7%
1980
16th to endDay
49%7%11%18%11%1
2112
April1st to 15thDay
52%5%12%18%10%
2119
16th to endDay
46%5%10%19%14%2
2340
May1st to 15thDay
45%8%11%22%10%
2358
16th to endDay
40%8%15%20%13%1
2622
June1st to 15thDay
41%9%13%23%12%
2520
16th to endDay
40%9%15%21%12%
2652
July1st to 15thDay
34%10%14%23%15%1
2428
16th to endDay
40%9%16%20%10%2
2360
August1st to 15thDay
39%10%16%18%13%1
2327
16th to endDay
39%8%16%24%9%
2429
September1st to 15thDay
41%8%15%23%10%
2130
16th to endDay
41%8%13%26%9%
1966
October1st to 15thDay
50%6%12%19%9%1
1800
16th to endDay
59%8%14%12%4
1920
November1st to 15thDay
47%9%16%18%7%
1486
16th to endDay
57%9%14%13%3
1440
December1st to 15thDay
66%9%12%10%1
1440
16th to endDay
69%9%10%8%2
1536
January1st to 15thNight
60%9%11%12%5%
2452
16th to endNight
59%8%12%13%5%
2496
February1st to 15thNight
57%8%13%14%4
2287
16th to endNight
54%7%13%15%7%
2009
March1st to 15thNight
52%7%13%19%6%
1980
16th to endNight
45%5%8%21%16%2
2112
April1st to 15thNight
48%6%10%18%14%
1830
16th to endNight
41%6%10%21%17%3
1628
May1st to 15thNight
42%7%11%23%13%2
1591
16th to endNight
34%7%14%24%15%3
1497
June1st to 15thNight
37%9%12%23%16%1
1440
16th to endNight
35%6%13%26%16%
1302
July1st to 15thNight
24%7%12%27%25%2
1298
16th to endNight
31%8%15%24%16%2
1543
August1st to 15thNight
28%8%18%29%12%2
1609
16th to endNight
31%7%11%30%16%2
1761
September1st to 15thNight
33%7%14%28%15%1
1827
16th to endNight
34%6%12%31%13%
1992
October1st to 15thNight
43%7%11%22%14%
2160
16th to endNight
51%8%14%18%6%
2303
November1st to 15thNight
44%8%14%19%12%1
2369
16th to endNight
53%10%16%14%5%
2520
December1st to 15thNight
59%11%13%12%3
2520
16th to endNight
67%9%11%9%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
11%31%39%11%5%
69
16th to endDay
27%28%34%10%
96
February1st to 15thDay
17%30%41%8%2
90
16th to endDay
22%24%40%12%
81
March1st to 15thDay
19%18%31%23%6%
270
16th to endDay
22%11%35%21%8%1
288
April1st to 15thDay
18%19%32%21%6%1
270
16th to endDay
20%12%29%22%10%4
270
May1st to 15thDay
20%6%28%22%14%5%
288
16th to endDay
13%6%34%24%14%5%
331
June1st to 15thDay
17%7%28%30%13%2
315
16th to endDay
13%9%29%32%12%3
447
July1st to 15thDay
9%5%25%35%15%8%
362
16th to endDay
8%327%32%19%7%
326
August1st to 15thDay
9%322%29%21%13%
313
16th to endDay
12%418%29%18%15%
332
September1st to 15thDay
11%320%27%23%12%
315
16th to endDay
16%417%24%22%14%
314
October1st to 15thDay
21%10%28%18%15%6%
315
16th to endDay
23%17%31%19%8%
336
November1st to 15thDay
9%16%34%27%8%3
86
16th to endDay
20%26%28%16%8%
60
December1st to 15thDay
20%35%26%16%1
60
16th to endDay
21%34%40%3
64
January1st to 15thNight
23%23%35%14%2
720
16th to endNight
17%16%41%19%4
768
February1st to 15thNight
18%22%38%17%2
704
16th to endNight
17%18%35%22%4
631
March1st to 15thNight
23%15%35%22%3
720
16th to endNight
17%13%35%24%8%
768
April1st to 15thNight
21%13%36%23%4
718
16th to endNight
14%9%34%29%10%1
548
May1st to 15thNight
16%6%26%33%15%1
511
16th to endNight
14%332%30%18%
375
June1st to 15thNight
13%5%29%36%14%
360
16th to endNight
9%328%41%15%
360
July1st to 15thNight
6%224%43%22%
340
16th to endNight
8%125%40%21%1
512
August1st to 15thNight
7%118%43%24%3
539
16th to endNight
11%220%33%28%3
615
September1st to 15thNight
12%6%23%30%21%5%
720
16th to endNight
13%6%19%28%25%6%
717
October1st to 15thNight
19%8%27%25%14%3
720
16th to endNight
23%15%34%23%4
768
November1st to 15thNight
17%12%33%24%11%1
700
16th to endNight
21%18%31%21%6%
720
December1st to 15thNight
25%20%34%15%2
720
16th to endNight
25%20%36%15%2
768
Page generated at 2017-11-01 17:23:35. Version ac04

Copyright 2017 A. Danko


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