Coral Key Village Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coral Key Village Observatory clear sky chart from 2005-11-05 to 2017-09-23.

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
69%
16283
17%
47049
16%
16247
70%
16247
29%
30364

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
62%
716
18%
2327
19%
716
64%
716
26%
1444
January16th to endNight
61%
768
25%
2403
24%
768
66%
768
31%
1424
February1st to 15thNight
62%
701
26%
2106
22%
701
66%
701
34%
1252
February16th to endNight
73%
631
29%
1735
25%
631
76%
631
42%
985
March1st to 15thNight
71%
720
24%
1980
18%
720
74%
720
39%
1183
March16th to endNight
70%
768
26%
2112
24%
768
72%
768
40%
1242
April1st to 15thNight
78%
718
23%
1976
20%
718
80%
718
44%
1129
April16th to endNight
72%
720
25%
1846
18%
720
73%
720
40%
1127
May1st to 15thNight
81%
719
25%
1799
18%
719
82%
719
52%
1004
May16th to endNight
68%
615
15%
1737
13%
615
68%
615
28%
1152
June1st to 15thNight
58%
540
7%
1620
7%
540
58%
540
15%
1232
June16th to endNight
74%
540
7%
1620
7%
540
74%
540
20%
1134
July1st to 15thNight
75%
510
6%
1530
6%
510
75%
510
23%
1017
July16th to endNight
80%
564
13%
1595
13%
531
80%
531
31%
981
August1st to 15thNight
78%
608
9%
1694
7%
605
78%
605
27%
1113
August16th to endNight
70%
764
7%
2101
7%
764
70%
764
22%
1516
September1st to 15thNight
68%
720
4%
1980
4%
720
68%
720
18%
1500
September16th to endNight
65%
689
5%
1903
5%
689
65%
689
18%
1462
October1st to 15thNight
65%
660
12%
1890
14%
660
66%
660
20%
1368
October16th to endNight
59%
704
15%
2112
16%
704
60%
704
20%
1517
November1st to 15thNight
64%
700
23%
2101
21%
700
68%
700
29%
1306
November16th to endNight
63%
720
23%
2160
23%
720
66%
720
28%
1378
December1st to 15thNight
66%
720
20%
2226
20%
720
68%
720
27%
1432
December16th to endNight
69%
768
22%
2496
23%
768
71%
768
31%
1466

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
6%425%5%36%6%8%12%39%
47837
Night
6%425%5%35%6%8%11%38%
47251
TransparencyDay
33%10%20%21%10%2
47538
Night
36%9%19%21%11%2
47054
SeeingDay
9%16%20%34%27%
6095
Night
8%18%25%36%19%
16293

By Month

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
7%4245%25%7%6%13%39%
1611
16th to endDay
6%5%245%36%6%8%11%40%
1818
February1st to 15thDay
7%4243245%6%9%48%
1750
16th to endDay
421223447%10%56%
1738
March1st to 15thDay
32134246%8%11%50%
1980
16th to endDay
5%21332446%10%54%
2111
April1st to 15thDay
3212225%46%12%57%
1972
16th to endDay
43133235%6%10%54%
2112
May1st to 15thDay
421332335%10%58%
2152
16th to endDay
7%5%25%5%36%7%8%12%36%
2384
June1st to 15thDay
9%6%47%8%47%7%8%12%22%
2340
16th to endDay
5%426%6%48%9%10%13%28%
2340
July1st to 15thDay
5%327%5%37%7%11%16%28%
2340
16th to endDay
33145%47%8%10%16%32%
2465
August1st to 15thDay
35%26%7%37%8%10%14%29%
2235
16th to endDay
7%427%6%5%7%8%9%14%27%
2101
September1st to 15thDay
6%5%26%8%5%9%8%11%13%22%
1980
16th to endDay
7%8%36%7%5%7%7%10%12%23%
1894
October1st to 15thDay
8%5%26%8%5%6%6%8%12%29%
1738
16th to endDay
12%6%25%6%45%6%7%11%31%
1760
November1st to 15thDay
7%3243345%5%10%48%
1757
16th to endDay
6%423435%5%7%8%46%
1800
December1st to 15thDay
7%5%25%436%5%6%10%40%
1731
16th to endDay
4224435%7%9%12%43%
1728
January1st to 15thNight
7%436%6%35%6%8%12%35%
2327
16th to endNight
6%4245%35%6%7%9%44%
2403
February1st to 15thNight
8%4244345%5%9%46%
2100
16th to endNight
33135%25%5%6%9%53%
1735
March1st to 15thNight
3325%446%6%7%8%49%
1980
16th to endNight
33245%35%6%6%10%48%
2112
April1st to 15thNight
33133345%6%10%53%
1976
16th to endNight
5%324325%5%8%9%48%
1846
May1st to 15thNight
221332246%10%59%
1799
16th to endNight
10%426%5%35%48%9%37%
1736
June1st to 15thNight
10%9%39%7%5%5%6%7%10%23%
1620
16th to endNight
4325%7%47%9%9%17%27%
1620
July1st to 15thNight
4325%6%45%7%10%15%33%
1620
16th to endNight
33245%36%7%9%14%38%
1703
August1st to 15thNight
3425%6%36%9%8%14%35%
1705
16th to endNight
6%5%36%7%5%7%7%9%12%29%
2101
September1st to 15thNight
6%6%26%8%38%8%9%11%26%
1980
16th to endNight
7%7%38%8%5%6%8%10%10%22%
1903
October1st to 15thNight
9%6%26%8%47%8%9%10%26%
1890
16th to endNight
12%7%37%7%46%6%6%8%30%
2112
November1st to 15thNight
9%425%435%5%8%10%39%
2101
16th to endNight
9%425%5%35%5%7%11%38%
2160
December1st to 15thNight
8%5%35%5%45%5%7%10%38%
2226
16th to endNight
7%425%435%5%8%10%42%
2496

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
34%7%17%25%10%3
1612
16th to endDay
33%6%16%23%15%4
1818
February1st to 15thDay
29%5%12%29%16%4
1752
16th to endDay
20%5%15%34%18%5%
1738
March1st to 15thDay
24%6%17%29%19%2
1980
16th to endDay
23%6%18%29%18%3
2112
April1st to 15thDay
20%5%18%37%16%2
1972
16th to endDay
22%7%16%31%18%3
2112
May1st to 15thDay
21%419%32%16%5%
2152
16th to endDay
36%10%21%26%6%
2388
June1st to 15thDay
50%12%21%12%2
2340
16th to endDay
38%17%32%10%
2340
July1st to 15thDay
37%18%32%12%
2201
16th to endDay
30%18%36%14%1
2310
August1st to 15thDay
35%17%26%17%2
2222
16th to endDay
39%18%28%12%
2101
September1st to 15thDay
44%19%24%9%1
1980
16th to endDay
45%15%24%11%2
1894
October1st to 15thDay
43%12%16%18%6%2
1738
16th to endDay
44%8%13%19%9%3
1760
November1st to 15thDay
30%6%14%23%22%2
1757
16th to endDay
34%6%12%17%22%6%
1800
December1st to 15thDay
36%9%13%22%17%1
1731
16th to endDay
29%8%15%25%18%2
1728
January1st to 15thNight
37%7%17%25%8%2
2327
16th to endNight
32%7%15%25%16%3
2403
February1st to 15thNight
33%5%10%28%16%5%
2109
16th to endNight
26%5%16%24%20%6%
1735
March1st to 15thNight
30%6%14%27%19%2
1980
16th to endNight
28%6%15%28%17%3
2112
April1st to 15thNight
25%6%15%32%17%2
1976
16th to endNight
29%6%13%27%19%2
1846
May1st to 15thNight
20%6%16%32%19%4
1800
16th to endNight
38%8%17%25%9%
1738
June1st to 15thNight
52%11%20%10%3
1620
16th to endNight
38%17%32%11%
1620
July1st to 15thNight
34%16%35%13%
1530
16th to endNight
28%13%36%18%2
1595
August1st to 15thNight
33%14%30%20%1
1694
16th to endNight
40%14%29%15%
2101
September1st to 15thNight
43%17%27%10%1
1980
16th to endNight
49%13%23%11%2
1903
October1st to 15thNight
45%11%19%14%7%1
1890
16th to endNight
50%7%12%17%9%3
2112
November1st to 15thNight
36%6%14%22%17%1
2101
16th to endNight
39%6%12%18%18%4
2160
December1st to 15thNight
39%7%15%22%14%1
2226
16th to endNight
34%6%13%28%15%1
2496

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
25%315%24%30%1
90
16th to endDay
12%9%18%35%20%3
96
February1st to 15thDay
3214%38%36%4
90
16th to endDay
7%115%39%33%1
239
March1st to 15thDay
7%214%44%28%2
270
16th to endDay
6%114%37%33%5%
288
April1st to 15thDay
37%41%42%4
270
16th to endDay
9%6%38%43%1
270
May1st to 15thDay
41330%49%11%
288
16th to endDay
6%1310%46%31%
331
June1st to 15thDay
17%413%34%30%
315
16th to endDay
6%6%27%58%
315
July1st to 15thDay
41431%57%
305
16th to endDay
7%2228%57%
326
August1st to 15thDay
6%1434%53%
313
16th to endDay
11%5%28%53%
332
September1st to 15thDay
11%11422%58%
315
16th to endDay
11%12423%56%
283
October1st to 15thDay
11%1319%44%19%
255
16th to endDay
16%213%21%33%12%
272
November1st to 15thDay
9%18%27%40%12%
265
16th to endDay
8%219%30%35%3
270
December1st to 15thDay
17%26%28%37%6%
201
16th to endDay
3112%19%52%11%
96
January1st to 15thNight
8%314%31%36%5%
720
16th to endNight
8%418%34%30%3
768
February1st to 15thNight
9%216%36%32%2
704
16th to endNight
5%212%39%36%3
631
March1st to 15thNight
5%114%39%36%2
720
16th to endNight
5%114%39%34%4
768
April1st to 15thNight
418%38%43%3
718
16th to endNight
6%110%38%39%3
720
May1st to 15thNight
46%31%46%10%
720
16th to endNight
10%15%19%47%16%
617
June1st to 15thNight
14%15%13%35%29%
540
16th to endNight
4129%35%47%
540
July1st to 15thNight
5%26%33%51%
510
16th to endNight
32430%58%
564
August1st to 15thNight
5%1436%51%
608
16th to endNight
9%36%33%46%
764
September1st to 15thNight
9%37%30%49%
720
16th to endNight
11%37%29%47%
689
October1st to 15thNight
12%5%18%41%21%
660
16th to endNight
17%17%23%33%16%
704
November1st to 15thNight
10%212%30%34%9%
700
16th to endNight
10%212%33%35%5%
720
December1st to 15thNight
10%29%37%35%4
720
16th to endNight
9%19%32%37%9%
768
Page generated at 2017-09-24 09:15:47. Version ac04

Copyright 2017 A. Danko


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