Boca Raton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Boca Raton clear sky chart from 2005-11-05 to 2017-08-12.

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
55%
16135
17%
46537
13%
16098
60%
16098
24%
30549

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
44%
716
16%
2327
10%
716
52%
716
19%
1497
January16th to endNight
47%
768
22%
2496
17%
768
55%
768
26%
1472
February1st to 15thNight
49%
701
25%
2087
20%
700
56%
700
30%
1239
February16th to endNight
51%
631
28%
1735
15%
631
63%
631
30%
1028
March1st to 15thNight
46%
720
24%
1980
14%
720
55%
720
31%
1177
March16th to endNight
53%
768
24%
2112
17%
768
59%
768
32%
1242
April1st to 15thNight
63%
718
23%
1961
17%
718
69%
718
38%
1088
April16th to endNight
55%
720
23%
1800
12%
720
60%
720
30%
1118
May1st to 15thNight
63%
719
23%
1800
14%
719
66%
719
40%
1052
May16th to endNight
60%
622
15%
1743
11%
622
62%
622
24%
1184
June1st to 15thNight
56%
540
9%
1620
7%
540
57%
540
15%
1217
June16th to endNight
65%
540
9%
1620
7%
540
66%
540
19%
1132
July1st to 15thNight
64%
510
5%
1530
5%
510
64%
510
17%
1127
July16th to endNight
66%
564
9%
1595
8%
531
71%
531
24%
1066
August1st to 15thNight
68%
609
6%
1657
6%
606
68%
606
26%
1119
August16th to endNight
63%
700
5%
1813
4%
700
63%
700
19%
1377
September1st to 15thNight
60%
660
4%
1815
4%
660
60%
660
14%
1425
September16th to endNight
53%
657
5%
1815
2%
657
56%
657
11%
1466
October1st to 15thNight
60%
660
17%
1933
19%
660
61%
660
21%
1345
October16th to endNight
48%
704
17%
2112
15%
704
52%
704
20%
1454
November1st to 15thNight
54%
700
24%
2101
21%
700
59%
700
28%
1291
November16th to endNight
43%
720
22%
2160
16%
720
52%
720
20%
1456
December1st to 15thNight
48%
720
20%
2229
16%
720
54%
720
21%
1473
December16th to endNight
56%
768
21%
2496
18%
768
63%
768
25%
1504

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
8%5%37%7%47%7%8%10%29%
47416
Night
7%425%6%36%6%7%10%38%
46738
TransparencyDay
45%12%15%15%9%2
47118
Night
37%9%18%20%11%2
46540
SeeingDay
8%9%9%21%26%24%
5945
Night
8%15%10%24%27%13%
16145

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
11%6%28%6%35%6%7%10%30%
1611
16th to endDay
9%6%35%6%47%5%7%8%36%
1728
February1st to 15thDay
11%5%25%5%3445%10%38%
1767
16th to endDay
7%4346%35%5%6%8%43%
1738
March1st to 15thDay
5%426%6%46%6%7%12%37%
1980
16th to endDay
6%436%6%37%6%6%10%38%
2111
April1st to 15thDay
6%325%5%36%6%8%11%40%
1984
16th to endDay
7%425%5%36%8%8%10%36%
2160
May1st to 15thDay
3325%5%46%7%8%10%42%
2152
16th to endDay
10%6%37%7%5%6%8%8%10%24%
2377
June1st to 15thDay
12%7%49%9%5%9%9%8%8%16%
2340
16th to endDay
7%6%28%8%48%9%10%11%20%
2340
July1st to 15thDay
9%6%38%7%48%8%10%12%19%
2340
16th to endDay
6%5%38%9%6%7%7%9%13%22%
2465
August1st to 15thDay
7%6%38%9%5%7%8%9%14%21%
2193
16th to endDay
9%5%38%9%5%9%9%9%11%18%
2031
September1st to 15thDay
9%6%39%11%6%10%9%8%9%15%
1815
16th to endDay
13%9%49%10%6%8%9%6%8%14%
1815
October1st to 15thDay
7%5%38%8%6%8%9%9%10%22%
1696
16th to endDay
14%6%27%8%45%5%6%8%28%
1760
November1st to 15thDay
9%5%26%7%38%6%7%9%34%
1757
16th to endDay
11%437%7%47%7%6%8%31%
1800
December1st to 15thDay
10%7%38%6%36%5%7%8%32%
1728
16th to endDay
7%436%5%46%7%6%11%35%
1728
January1st to 15thNight
9%6%26%6%36%6%7%10%34%
2327
16th to endNight
6%424436%6%7%10%43%
2496
February1st to 15thNight
10%42442347%8%47%
2080
16th to endNight
5%225%6%346%6%10%47%
1735
March1st to 15thNight
5%4145%35%5%6%9%47%
1980
16th to endNight
5%3145%35%5%7%9%48%
2112
April1st to 15thNight
31134245%7%11%54%
1961
16th to endNight
5%324435%6%7%9%45%
1800
May1st to 15thNight
4313326%5%5%9%54%
1799
16th to endNight
8%436%6%36%7%8%11%33%
1743
June1st to 15thNight
11%5%38%7%47%8%8%11%24%
1620
16th to endNight
5%435%6%48%7%9%13%31%
1620
July1st to 15thNight
6%5%47%7%46%6%8%10%31%
1620
16th to endNight
43245%47%5%8%12%39%
1703
August1st to 15thNight
5%4245%36%6%9%13%37%
1668
16th to endNight
7%5%26%7%47%8%7%12%29%
1813
September1st to 15thNight
6%5%37%8%5%8%10%9%13%20%
1815
16th to endNight
10%6%38%9%5%9%7%8%10%19%
1815
October1st to 15thNight
7%5%37%7%47%8%8%11%29%
1933
16th to endNight
14%7%26%6%45%5%6%7%32%
2112
November1st to 15thNight
7%5%25%6%35%6%6%9%41%
2101
16th to endNight
11%6%35%6%36%6%5%10%34%
2160
December1st to 15thNight
10%5%36%5%37%6%6%9%36%
2229
16th to endNight
7%425%5%36%6%6%10%41%
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
45%9%12%15%13%4
1612
16th to endDay
42%7%10%18%14%6%
1728
February1st to 15thDay
39%6%9%22%15%5%
1770
16th to endDay
35%6%13%22%14%6%
1738
March1st to 15thDay
36%8%14%23%14%3
1980
16th to endDay
37%7%14%21%14%5%
2112
April1st to 15thDay
34%8%16%22%15%2
1984
16th to endDay
37%10%11%20%17%3
2160
May1st to 15thDay
33%8%14%23%15%5%
2152
16th to endDay
48%11%15%17%7%
2381
June1st to 15thDay
57%14%12%10%4
2340
16th to endDay
49%18%19%11%1
2340
July1st to 15thDay
49%19%21%8%
2201
16th to endDay
45%19%23%10%
2310
August1st to 15thDay
46%17%24%10%1
2180
16th to endDay
52%17%21%7%
2031
September1st to 15thDay
55%18%17%6%1
1815
16th to endDay
63%15%11%6%3
1815
October1st to 15thDay
49%13%13%15%7%1
1696
16th to endDay
50%8%9%14%12%4
1760
November1st to 15thDay
40%8%11%17%17%4
1757
16th to endDay
47%7%9%13%16%6%
1800
December1st to 15thDay
46%9%11%16%14%2
1728
16th to endDay
40%7%12%19%16%3
1728
January1st to 15thNight
39%8%16%21%11%2
2327
16th to endNight
33%6%16%23%14%5%
2496
February1st to 15thNight
33%411%26%17%6%
2088
16th to endNight
29%7%14%27%16%5%
1735
March1st to 15thNight
30%6%15%25%17%4
1980
16th to endNight
29%6%16%26%16%4
2112
April1st to 15thNight
21%8%19%30%16%2
1961
16th to endNight
31%7%15%22%18%4
1800
May1st to 15thNight
25%6%15%33%14%5%
1800
16th to endNight
40%8%20%24%6%
1745
June1st to 15thNight
47%13%19%14%3
1620
16th to endNight
37%16%30%13%1
1620
July1st to 15thNight
44%16%27%10%
1530
16th to endNight
31%17%34%15%1
1595
August1st to 15thNight
32%16%34%15%1
1657
16th to endNight
42%18%27%10%1
1813
September1st to 15thNight
47%19%22%9%1
1815
16th to endNight
53%16%17%9%2
1815
October1st to 15thNight
42%10%16%17%10%1
1933
16th to endNight
47%6%12%18%11%4
2112
November1st to 15thNight
36%5%13%21%18%5%
2101
16th to endNight
45%5%9%17%14%7%
2160
December1st to 15thNight
41%8%13%18%15%2
2229
16th to endNight
35%7%13%23%17%3
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
21%324%28%22%
90
16th to endDay
14%8%21%36%12%6%
96
February1st to 15thDay
8%419%39%21%6%
112
16th to endDay
9%12%21%35%19%1
239
March1st to 15thDay
5%12%22%36%19%3
270
16th to endDay
6%12%18%34%23%5%
288
April1st to 15thDay
411%15%32%27%8%
270
16th to endDay
6%11%11%33%31%6%
270
May1st to 15thDay
311%6%27%37%14%
288
16th to endDay
8%10%314%33%30%
331
June1st to 15thDay
10%10%6%12%30%31%
315
16th to endDay
310%36%26%49%
315
July1st to 15thDay
6%6%327%55%
305
16th to endDay
39%16%27%50%
326
August1st to 15thDay
8%6%27%28%47%
297
16th to endDay
12%5%47%20%49%
268
September1st to 15thDay
7%6%310%25%47%
255
16th to endDay
14%5%212%22%42%
254
October1st to 15thDay
10%6%5%24%36%16%
255
16th to endDay
15%8%12%29%22%12%
272
November1st to 15thDay
11%10%9%30%26%11%
265
16th to endDay
9%12%20%31%26%
270
December1st to 15thDay
18%12%13%24%26%5%
198
16th to endDay
10%37%28%41%9%
96
January1st to 15thNight
11%20%15%28%21%2
720
16th to endNight
7%19%19%33%18%
768
February1st to 15thNight
8%18%17%36%18%
704
16th to endNight
5%16%20%37%19%
631
March1st to 15thNight
6%18%22%29%20%2
720
16th to endNight
6%17%16%35%22%1
768
April1st to 15thNight
317%9%39%25%3
718
16th to endNight
8%17%11%36%25%1
720
May1st to 15thNight
5%17%6%33%33%3
720
16th to endNight
8%17%5%18%37%12%
624
June1st to 15thNight
8%16%214%34%23%
540
16th to endNight
416%18%32%35%
540
July1st to 15thNight
6%11%16%34%38%
510
16th to endNight
416%430%42%
564
August1st to 15thNight
8%9%16%40%33%
609
16th to endNight
9%9%39%33%36%
700
September1st to 15thNight
8%9%310%33%35%
660
16th to endNight
15%9%311%29%31%
657
October1st to 15thNight
10%10%5%22%38%13%
660
16th to endNight
19%10%10%24%27%8%
704
November1st to 15thNight
9%15%14%30%24%5%
700
16th to endNight
13%17%15%29%21%3
720
December1st to 15thNight
11%18%14%30%23%2
720
16th to endNight
6%17%12%26%32%4
768
Page generated at 2017-08-13 14:16:43. Version ac04

Copyright 2017 A. Danko


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