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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 2018-03-11.

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%
16576
21%
49057
15%
16539
61%
16539
29%
30858

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
34%
776
20%
2522
10%
776
47%
776
22%
1587
January16th to endNight
38%
832
23%
2704
15%
832
50%
832
26%
1656
February1st to 15thNight
38%
761
21%
2287
13%
760
48%
760
27%
1437
February16th to endNight
39%
683
25%
1998
15%
683
49%
683
30%
1234
March1st to 15thNight
43%
764
27%
2101
15%
764
54%
764
37%
1231
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
75%
539
10%
1609
8%
536
76%
536
24%
1103
August16th to endNight
65%
699
11%
1966
10%
699
66%
699
21%
1414
September1st to 15thNight
64%
720
11%
1980
9%
720
64%
720
20%
1460
September16th to endNight
60%
717
16%
1980
15%
717
62%
717
21%
1437
October1st to 15thNight
61%
720
25%
2064
24%
720
65%
720
32%
1279
October16th to endNight
58%
768
31%
2304
27%
768
66%
768
34%
1337
November1st to 15thNight
55%
760
27%
2281
22%
760
64%
760
34%
1347
November16th to endNight
47%
780
27%
2467
20%
780
59%
780
31%
1442
December1st to 15thNight
45%
780
24%
2535
18%
780
55%
780
27%
1529
December16th to endNight
47%
832
22%
2704
18%
832
54%
832
25%
1668

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%26%6%36%5%6%8%37%
49556
Night
9%5%25%5%35%5%6%8%44%
49262
TransparencyDay
41%8%13%16%13%6%
49257
Night
35%8%14%19%14%7%
49065
SeeingDay
10%417%24%25%17%
6332
Night
11%5%20%31%26%5%
16586

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
13%7%36%5%44446%40%
1746
16th to endDay
12%6%26%434346%45%
1872
February1st to 15thDay
14%7%35%424345%44%
1897
16th to endDay
10%5%35%43335%5%49%
1759
March1st to 15thDay
8%42441345%7%52%
2096
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%
2340
16th to endDay
11%5%37%9%5%8%8%7%9%21%
2220
September1st to 15thDay
11%6%37%8%5%9%7%8%10%21%
1980
16th to endDay
15%8%39%8%46%6%6%6%24%
1980
October1st to 15thDay
10%6%36%7%46%5%6%7%36%
1896
16th to endDay
9%5%25%424446%49%
1920
November1st to 15thDay
8%425%5%35%45%8%46%
1907
16th to endDay
10%5%345%3445%6%47%
1820
December1st to 15thDay
12%6%26%5%2445%7%41%
1755
16th to endDay
9%6%35%435%5%5%8%42%
1872
January1st to 15thNight
12%7%35%5%2445%6%43%
2522
16th to endNight
14%5%3441335%6%46%
2704
February1st to 15thNight
12%6%25%423335%48%
2283
16th to endNight
9%6%25%6%24345%48%
1998
March1st to 15thNight
7%424423447%52%
2101
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%7%10%15%31%
1620
16th to endNight
9%6%25%6%46%6%8%12%31%
1966
September1st to 15thNight
10%5%36%6%5%6%7%7%11%28%
1980
16th to endNight
11%6%36%6%46%6%7%9%30%
1980
October1st to 15thNight
9%5%35%4245%5%7%46%
2064
16th to endNight
8%424434447%51%
2304
November1st to 15thNight
8%4244245%47%50%
2281
16th to endNight
8%425%434448%49%
2467
December1st to 15thNight
12%6%2443345%7%44%
2535
16th to endNight
10%6%26%5%2445%8%43%
2704

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
44%47%16%18%8%
1747
16th to endDay
39%47%17%20%10%
1872
February1st to 15thDay
42%5%7%11%19%13%
1899
16th to endDay
36%410%16%20%11%
1759
March1st to 15thDay
29%412%21%21%10%
2096
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
2327
16th to endDay
51%14%18%12%2
2220
September1st to 15thDay
52%12%15%11%6%
1980
16th to endDay
55%9%12%12%7%2
1980
October1st to 15thDay
45%6%9%15%14%8%
1896
16th to endDay
35%47%15%22%14%
1920
November1st to 15thDay
35%5%10%20%20%8%
1907
16th to endDay
36%410%16%21%10%
1820
December1st to 15thDay
40%5%13%19%13%7%
1755
16th to endDay
38%6%11%22%12%7%
1872
January1st to 15thNight
41%49%17%17%9%
2522
16th to endNight
38%48%15%21%11%
2704
February1st to 15thNight
38%5%8%15%18%13%
2292
16th to endNight
37%49%18%20%10%
1998
March1st to 15thNight
30%412%23%17%10%
2101
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
33%18%30%15%2
1609
16th to endNight
42%14%24%15%3
1966
September1st to 15thNight
45%13%19%13%6%
1980
16th to endNight
44%12%14%18%7%2
1980
October1st to 15thNight
35%6%12%18%19%7%
2064
16th to endNight
32%5%8%17%22%13%
2304
November1st to 15thNight
32%5%9%21%21%9%
2281
16th to endNight
33%5%10%19%18%12%
2467
December1st to 15thNight
37%414%20%14%7%
2535
16th to endNight
38%5%13%21%13%8%
2704

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
18%12%42%17%6%2
135
16th to endDay
11%15%37%27%9%
144
February1st to 15thDay
11%20%33%21%12%
135
16th to endDay
8%7%31%36%14%
169
March1st to 15thDay
11%8%30%32%15%1
312
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%
313
16th to endDay
12%16%15%27%37%
332
September1st to 15thDay
16%26%17%30%26%
315
16th to endDay
19%16%19%30%23%
314
October1st to 15thDay
14%316%27%29%7%
315
16th to endDay
11%5%20%30%26%5%
336
November1st to 15thDay
10%420%35%22%7%
325
16th to endDay
8%6%32%28%21%4
200
December1st to 15thDay
11%8%31%32%14%
135
16th to endDay
15%425%41%10%2
144
January1st to 15thNight
16%12%30%28%11%1
780
16th to endNight
15%10%31%32%9%
832
February1st to 15thNight
16%9%31%32%10%
764
16th to endNight
13%9%32%34%9%
683
March1st to 15thNight
9%9%32%37%10%
764
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%19%54%14%
539
16th to endNight
12%7%20%40%18%
699
September1st to 15thNight
13%16%22%42%12%
720
16th to endNight
14%110%26%36%10%
717
October1st to 15thNight
12%215%31%34%3
720
16th to endNight
10%419%36%26%3
768
November1st to 15thNight
10%423%36%24%1
760
16th to endNight
9%6%30%29%20%1
780
December1st to 15thNight
15%7%25%29%20%1
780
16th to endNight
13%8%24%35%16%1
832
Page generated at 2018-03-12 13:28:07. Version ac04

Copyright 2018 A. Danko


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