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Jacksonville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jacksonville 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
54%
15737
21%
46535
15%
15700
61%
15700
28%
29337

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
36%
716
20%
2327
11%
716
48%
716
22%
1455
January16th to endNight
38%
768
22%
2496
14%
768
50%
768
25%
1537
February1st to 15thNight
38%
701
23%
2107
13%
700
48%
700
28%
1301
February16th to endNight
35%
631
23%
1846
12%
631
47%
631
28%
1157
March1st to 15thNight
43%
720
27%
1980
15%
720
54%
720
36%
1172
March16th to endNight
48%
768
23%
2112
15%
768
55%
768
36%
1247
April1st to 15thNight
50%
718
24%
1976
15%
718
57%
718
36%
1179
April16th to endNight
55%
705
28%
1801
16%
705
61%
705
42%
1065
May1st to 15thNight
65%
539
25%
1619
18%
539
70%
539
39%
908
May16th to endNight
70%
561
22%
1682
18%
561
71%
561
35%
989
June1st to 15thNight
67%
540
14%
1620
11%
540
67%
540
26%
1071
June16th to endNight
75%
540
11%
1620
10%
540
75%
540
26%
1096
July1st to 15thNight
74%
510
11%
1530
10%
510
75%
510
24%
1035
July16th to endNight
76%
564
11%
1595
12%
531
77%
531
24%
1107
August1st to 15thNight
74%
527
10%
1575
8%
524
75%
524
23%
1085
August16th to endNight
65%
640
12%
1801
10%
640
65%
640
21%
1299
September1st to 15thNight
65%
660
11%
1815
10%
660
65%
660
21%
1322
September16th to endNight
57%
657
13%
1815
12%
657
59%
657
19%
1345
October1st to 15thNight
61%
660
26%
1892
24%
660
65%
660
32%
1170
October16th to endNight
59%
704
29%
2112
26%
704
66%
704
33%
1238
November1st to 15thNight
54%
700
27%
2101
22%
700
63%
700
33%
1255
November16th to endNight
45%
720
27%
2277
19%
720
57%
720
31%
1330
December1st to 15thNight
45%
720
24%
2340
19%
720
54%
720
26%
1425
December16th to endNight
47%
768
22%
2496
18%
768
54%
768
25%
1549

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
9%5%36%6%46%5%6%8%37%
47423
Night
9%5%25%5%35%5%6%8%44%
46740
TransparencyDay
41%8%13%16%13%6%
47124
Night
35%8%14%19%14%7%
46543
SeeingDay
10%417%23%25%18%
5582
Night
11%5%20%31%26%5%
15747

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
12%6%36%444447%41%
1611
16th to endDay
12%6%26%434346%44%
1728
February1st to 15thDay
14%6%34424335%46%
1747
16th to endDay
11%5%35%43335%5%48%
1625
March1st to 15thDay
9%42441345%7%52%
1980
16th to endDay
9%6%25%6%24347%47%
2111
April1st to 15thDay
9%5%245%3435%8%46%
1972
16th to endDay
6%425%4445%6%9%47%
2166
May1st to 15thDay
7%425%5%25%46%9%46%
2331
16th to endDay
8%325%6%47%6%7%9%37%
2431
June1st to 15thDay
10%436%8%5%6%7%8%8%30%
2340
16th to endDay
6%5%37%7%49%7%7%11%28%
2340
July1st to 15thDay
6%5%27%7%5%9%7%8%12%26%
2340
16th to endDay
7%439%8%5%8%9%7%11%23%
2465
August1st to 15thDay
9%6%38%10%5%8%9%8%10%20%
2288
16th to endDay
12%6%37%9%5%9%8%7%9%21%
2035
September1st to 15thDay
10%6%47%8%5%9%8%8%10%21%
1815
16th to endDay
16%8%39%8%46%6%6%6%22%
1815
October1st to 15thDay
10%7%36%7%45%5%6%7%36%
1738
16th to endDay
9%6%25%5%24446%48%
1760
November1st to 15thDay
8%425%5%35%5%5%8%45%
1757
16th to endDay
10%5%35%5%3445%6%45%
1680
December1st to 15thDay
12%6%26%5%2445%8%40%
1620
16th to endDay
9%6%35%435%5%5%8%42%
1728
January1st to 15thNight
11%7%35%5%25%45%6%43%
2327
16th to endNight
14%5%3441335%6%45%
2496
February1st to 15thNight
12%6%25%423335%49%
2103
16th to endNight
10%6%25%6%24345%47%
1846
March1st to 15thNight
7%425%434447%52%
1980
16th to endNight
7%414433445%55%
2112
April1st to 15thNight
7%4234245%47%52%
1976
16th to endNight
6%3133225%6%8%53%
1801
May1st to 15thNight
5%21342446%8%55%
1619
16th to endNight
6%3244346%6%10%47%
1682
June1st to 15thNight
9%4246%35%7%7%12%35%
1620
16th to endNight
7%3246%47%6%8%13%35%
1620
July1st to 15thNight
6%415%6%35%7%10%13%36%
1620
16th to endNight
4326%7%37%8%9%11%33%
1703
August1st to 15thNight
3325%6%47%8%10%15%30%
1586
16th to endNight
9%6%25%6%46%6%8%12%30%
1801
September1st to 15thNight
9%5%36%6%46%7%7%11%28%
1815
16th to endNight
12%6%36%7%47%6%8%9%27%
1815
October1st to 15thNight
9%5%35%4245%5%7%46%
1892
16th to endNight
8%5%24434447%50%
2112
November1st to 15thNight
8%425%425%5%47%49%
2101
16th to endNight
9%425%43445%8%48%
2277
December1st to 15thNight
12%6%2443345%7%43%
2340
16th to endNight
10%6%26%5%2445%7%43%
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
43%48%16%18%9%
1612
16th to endDay
40%47%17%19%10%
1728
February1st to 15thDay
41%47%11%20%14%
1749
16th to endDay
37%49%15%20%12%
1625
March1st to 15thDay
30%412%22%21%9%
1980
16th to endDay
37%412%16%20%8%
2112
April1st to 15thDay
35%5%9%18%21%9%
1972
16th to endDay
31%6%13%20%19%8%
2166
May1st to 15thDay
32%6%12%22%18%8%
2331
16th to endDay
38%10%14%18%15%4
2435
June1st to 15thDay
45%12%17%16%7%
2340
16th to endDay
44%13%20%14%5%
2340
July1st to 15thDay
44%13%24%14%1
2201
16th to endDay
48%14%21%13%2
2310
August1st to 15thDay
51%14%21%10%1
2275
16th to endDay
52%14%18%12%2
2035
September1st to 15thDay
52%12%16%11%6%
1815
16th to endDay
58%9%11%11%6%2
1815
October1st to 15thDay
44%5%9%15%15%9%
1738
16th to endDay
35%48%16%21%12%
1760
November1st to 15thDay
35%5%9%19%20%9%
1757
16th to endDay
37%5%10%15%19%11%
1680
December1st to 15thDay
41%5%12%20%14%6%
1620
16th to endDay
39%6%11%22%12%7%
1728
January1st to 15thNight
41%410%17%16%9%
2327
16th to endNight
38%49%15%20%11%
2496
February1st to 15thNight
37%47%15%19%15%
2112
16th to endNight
38%49%17%19%11%
1846
March1st to 15thNight
31%412%23%17%9%
1980
16th to endNight
30%5%13%20%19%10%
2112
April1st to 15thNight
30%6%10%21%20%10%
1976
16th to endNight
25%6%15%23%21%6%
1801
May1st to 15thNight
25%8%15%25%18%6%
1620
16th to endNight
29%8%17%26%15%2
1684
June1st to 15thNight
36%11%21%23%6%
1620
16th to endNight
36%13%22%20%6%
1620
July1st to 15thNight
34%16%26%20%1
1530
16th to endNight
34%17%24%20%2
1595
August1st to 15thNight
34%18%29%15%2
1575
16th to endNight
42%14%23%16%3
1801
September1st to 15thNight
44%13%20%14%6%
1815
16th to endNight
46%12%13%16%7%2
1815
October1st to 15thNight
35%6%11%18%19%8%
1892
16th to endNight
32%5%8%17%22%13%
2112
November1st to 15thNight
33%5%9%20%20%10%
2101
16th to endNight
33%5%10%19%17%13%
2277
December1st to 15thNight
38%414%21%14%6%
2340
16th to endNight
39%5%12%20%13%8%
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
16%12%37%20%8%4
90
16th to endDay
10%17%37%25%9%
96
February1st to 15thDay
7%25%31%23%12%
90
16th to endDay
11%9%38%32%8%
126
March1st to 15thDay
13%7%28%33%15%1
270
16th to endDay
13%5%29%22%25%4
288
April1st to 15thDay
11%12%22%26%19%7%
270
16th to endDay
5%423%27%22%17%
270
May1st to 15thDay
7%422%29%21%13%
288
16th to endDay
6%310%23%35%21%
331
June1st to 15thDay
11%19%19%28%28%
315
16th to endDay
8%16%16%32%35%
315
July1st to 15thDay
3314%32%45%
305
16th to endDay
6%15%19%33%33%
326
August1st to 15thDay
11%6%18%32%30%
297
16th to endDay
11%16%15%28%36%
268
September1st to 15thDay
13%17%14%30%30%
255
16th to endDay
22%27%17%27%24%
254
October1st to 15thDay
13%417%27%29%6%
255
16th to endDay
11%321%27%29%6%
272
November1st to 15thDay
12%421%31%22%7%
265
16th to endDay
8%6%36%24%20%4
150
December1st to 15thDay
8%7%37%31%13%1
90
16th to endDay
16%426%35%13%4
96
January1st to 15thNight
15%13%28%29%11%1
720
16th to endNight
16%10%30%32%9%
768
February1st to 15thNight
15%9%32%32%9%
704
16th to endNight
14%10%34%34%6%
631
March1st to 15thNight
10%9%31%36%10%
720
16th to endNight
10%7%30%35%16%
768
April1st to 15thNight
9%6%28%39%15%
718
16th to endNight
7%5%26%38%20%
705
May1st to 15thNight
5%221%43%24%2
540
16th to endNight
7%112%30%41%7%
563
June1st to 15thNight
11%18%31%38%9%
540
16th to endNight
8%5%25%45%14%
540
July1st to 15thNight
7%421%46%18%
510
16th to endNight
4222%55%14%
564
August1st to 15thNight
45%20%53%15%
527
16th to endNight
12%7%20%41%17%
640
September1st to 15thNight
12%16%21%43%13%
660
16th to endNight
15%110%26%34%10%
657
October1st to 15thNight
12%215%32%34%3
660
16th to endNight
10%417%36%27%3
704
November1st to 15thNight
10%424%35%23%1
700
16th to endNight
9%6%32%28%20%2
720
December1st to 15thNight
15%8%25%29%19%1
720
16th to endNight
13%8%24%35%16%1
768
Page generated at 2017-08-13 14:16:49. Version ac04

Copyright 2017 A. Danko


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