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 2017-04-26.

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%
14460
14%
45481
8%
14423
38%
14423
18%
31707

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
36%
536
20%
1592
8%
536
44%
536
26%
1032
May1st to 15thNight
44%
469
17%
1459
12%
469
51%
469
25%
956
May16th to endNight
47%
342
17%
1369
14%
342
57%
342
25%
772
June1st to 15thNight
43%
330
13%
1320
11%
330
54%
330
20%
791
June16th to endNight
51%
330
14%
1194
15%
330
59%
330
28%
688
July1st to 15thNight
61%
310
18%
1183
23%
310
67%
310
36%
591
July16th to endNight
59%
474
14%
1421
12%
441
61%
441
31%
827
August1st to 15thNight
63%
494
18%
1474
13%
491
67%
491
35%
864
August16th to endNight
56%
563
21%
1613
13%
563
60%
563
34%
988
September1st to 15thNight
51%
660
21%
1675
10%
660
57%
660
34%
1082
September16th to endNight
53%
657
20%
1826
14%
657
57%
657
31%
1146
October1st to 15thNight
37%
660
18%
1980
14%
660
44%
660
23%
1330
October16th to endNight
21%
704
12%
2112
5%
704
29%
704
15%
1575
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%47%6%35%5%5%7%32%
46160
Night
13%7%36%5%35%45%7%35%
45662
Cloud CoverDay
13%8%36%6%35%5%5%7%32%
46170
Night
14%7%36%5%35%45%6%36%
45666
TransparencyDay
49%8%13%18%9%
45860
Night
47%8%13%19%10%1
45481
SeeingDay
16%11%28%25%13%5%
4938
Night
17%12%31%25%10%1
14467

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%23336%39%
2287
May1st to 15thDay
14%5%46%6%346%6%6%35%
2161
16th to endDay
10%5%35%5%35%5%5%8%41%
2394
June1st to 15thDay
14%5%25%5%35%5%6%9%36%
2310
16th to endDay
11%425%6%36%5%6%11%37%
2431
July1st to 15thDay
6%425%5%36%6%8%9%40%
2362
16th to endDay
9%425%7%37%5%7%9%36%
2330
August1st to 15thDay
7%5%26%7%45%5%6%9%38%
2145
16th to endDay
11%5%25%5%36%5%7%8%38%
2226
September1st to 15thDay
13%6%35%6%35%45%7%38%
1953
16th to endDay
13%6%35%6%3445%8%38%
1802
October1st to 15thDay
17%7%35%6%4445%5%34%
1650
16th to endDay
22%10%48%6%45%45%5%22%
1760
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%
1592
May1st to 15thNight
13%5%145%35%5%5%7%42%
1459
16th to endNight
11%324415%45%6%49%
1367
June1st to 15thNight
11%435%5%345%6%8%40%
1320
16th to endNight
8%425%5%25%45%8%48%
1194
July1st to 15thNight
4323325%447%58%
1262
16th to endNight
7%3244245%6%8%50%
1528
August1st to 15thNight
6%325%4145%5%8%51%
1485
16th to endNight
9%4244245%46%51%
1613
September1st to 15thNight
11%5%1442445%7%48%
1675
16th to endNight
11%5%2442435%7%47%
1826
October1st to 15thNight
15%6%27%4235%46%40%
1980
16th to endNight
19%10%36%5%3445%6%29%
2112
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%24335%39%
2287
May1st to 15thDay
14%6%36%5%346%6%7%35%
2161
16th to endDay
10%435%5%445%6%8%41%
2394
June1st to 15thDay
14%5%25%5%35%5%6%8%37%
2310
16th to endDay
12%425%5%36%5%6%11%37%
2431
July1st to 15thDay
7%4246%36%6%7%9%41%
2362
16th to endDay
9%425%6%36%6%7%9%37%
2330
August1st to 15thDay
8%5%26%6%45%5%7%9%38%
2145
16th to endDay
11%425%5%345%6%8%39%
2226
September1st to 15thDay
14%5%25%7%245%5%8%38%
1953
16th to endDay
14%5%26%435%45%7%39%
1802
October1st to 15thDay
18%6%35%6%45%446%34%
1650
16th to endDay
23%8%46%7%35%5%5%6%23%
1760
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%7%26%5%3345%5%44%
1592
May1st to 15thNight
13%5%245%35%45%7%42%
1458
16th to endNight
10%41443445%7%49%
1367
June1st to 15thNight
12%425%5%345%6%8%41%
1320
16th to endNight
8%4236%2435%8%48%
1194
July1st to 15thNight
4314325%35%8%58%
1262
16th to endNight
6%323435%5%5%8%50%
1528
August1st to 15thNight
7%3143345%6%7%51%
1485
16th to endNight
9%4245%235%45%52%
1613
September1st to 15thNight
11%42432445%6%48%
1675
16th to endNight
12%425%324447%48%
1826
October1st to 15thNight
16%6%26%5%2435%7%41%
1980
16th to endNight
19%9%36%5%3445%5%31%
2112
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%20%15%2
2287
May1st to 15thDay
45%9%11%22%10%
2161
16th to endDay
39%8%15%20%14%1
2398
June1st to 15thDay
41%9%13%22%11%
2310
16th to endDay
40%9%15%21%12%
2431
July1st to 15thDay
34%10%13%23%15%1
2213
16th to endDay
40%10%16%19%10%2
2174
August1st to 15thDay
39%9%16%18%13%1
2132
16th to endDay
39%8%16%24%9%
2226
September1st to 15thDay
42%8%15%23%9%
1953
16th to endDay
43%8%14%25%8%
1802
October1st to 15thDay
50%7%12%18%9%1
1650
16th to endDay
60%8%13%11%4
1760
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
40%6%10%21%17%3
1592
May1st to 15thNight
40%7%12%24%13%2
1459
16th to endNight
33%7%13%25%16%3
1369
June1st to 15thNight
37%9%12%23%16%1
1320
16th to endNight
34%6%14%26%16%1
1194
July1st to 15thNight
24%7%13%26%25%3
1183
16th to endNight
30%8%15%23%17%3
1421
August1st to 15thNight
29%7%18%28%13%2
1474
16th to endNight
32%7%11%29%16%2
1613
September1st to 15thNight
33%7%14%28%14%
1675
16th to endNight
35%6%13%30%12%1
1826
October1st to 15thNight
43%7%11%22%13%
1980
16th to endNight
53%8%14%17%6%
2112
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%28%22%11%4
254
May1st to 15thDay
16%7%27%23%17%7%
228
16th to endDay
11%5%32%27%16%7%
267
June1st to 15thDay
17%8%29%27%13%3
255
16th to endDay
13%7%26%33%15%3
376
July1st to 15thDay
9%5%26%35%15%8%
297
16th to endDay
7%427%33%18%8%
270
August1st to 15thDay
9%422%29%22%13%
253
16th to endDay
11%317%30%19%16%
268
September1st to 15thDay
12%319%29%22%12%
255
16th to endDay
18%417%28%19%11%
254
October1st to 15thDay
19%10%27%20%16%5%
255
16th to endDay
26%15%31%19%6%
272
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%10%33%29%10%1
536
May1st to 15thNight
14%6%27%32%16%2
469
16th to endNight
13%331%30%19%
343
June1st to 15thNight
14%5%29%35%13%
330
16th to endNight
8%328%41%17%
330
July1st to 15thNight
5%224%44%22%
310
16th to endNight
8%126%40%20%2
474
August1st to 15thNight
8%119%42%24%3
494
16th to endNight
12%220%33%27%3
563
September1st to 15thNight
13%6%23%29%21%5%
660
16th to endNight
14%6%20%30%24%4
657
October1st to 15thNight
19%9%28%25%14%2
660
16th to endNight
24%14%35%22%3
704
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 2017-04-27 17:48:46. Version ac04

Copyright 2017 A. Danko


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