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 2017-10-06.

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
45%
16007
21%
47272
13%
15968
53%
15968
27%
29872

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
30%
717
21%
2327
11%
716
43%
716
19%
1474
January16th to endNight
28%
768
23%
2496
10%
768
45%
768
22%
1551
February1st to 15thNight
26%
703
19%
2263
9%
701
40%
701
22%
1398
February16th to endNight
27%
631
26%
1863
11%
631
44%
631
24%
1151
March1st to 15thNight
29%
720
24%
1980
12%
720
40%
720
31%
1225
March16th to endNight
34%
768
22%
2112
12%
768
43%
768
29%
1330
April1st to 15thNight
35%
718
23%
1796
9%
718
43%
718
34%
1155
April16th to endNight
40%
720
21%
1800
9%
720
45%
720
34%
1145
May1st to 15thNight
42%
682
16%
1762
8%
682
47%
682
31%
1158
May16th to endNight
62%
561
17%
1683
12%
561
65%
561
30%
1032
June1st to 15thNight
60%
390
16%
1470
17%
390
62%
390
24%
882
June16th to endNight
61%
465
14%
1545
13%
465
63%
465
26%
957
July1st to 15thNight
66%
510
11%
1530
10%
510
67%
510
25%
1020
July16th to endNight
69%
564
10%
1595
7%
531
71%
531
27%
1025
August1st to 15thNight
65%
593
14%
1663
10%
590
65%
590
25%
1142
August16th to endNight
63%
764
15%
1910
9%
764
64%
764
26%
1347
September1st to 15thNight
63%
720
22%
1800
16%
720
66%
720
29%
1227
September16th to endNight
47%
717
15%
1981
12%
717
51%
717
21%
1433
October1st to 15thNight
50%
684
26%
2051
23%
684
58%
684
30%
1260
October16th to endNight
47%
704
32%
2112
23%
704
61%
704
35%
1185
November1st to 15thNight
46%
700
27%
2101
18%
700
58%
700
33%
1223
November16th to endNight
40%
720
26%
2335
16%
720
52%
720
27%
1382
December1st to 15thNight
38%
720
20%
2520
14%
720
50%
720
22%
1550
December16th to endNight
33%
768
22%
2577
14%
768
45%
768
20%
1620

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
12%6%25%5%35%5%6%7%40%
47884
Night
11%5%2442445%8%44%
47467
Cloud CoverDay
12%5%25%5%345%6%7%40%
47894
Night
11%5%25%42445%8%44%
47471
TransparencyDay
40%7%12%19%15%3
47596
Night
37%7%12%20%17%5%
47273
SeeingDay
15%8%23%26%17%8%
5967
Night
15%8%25%30%17%2
16013

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
15%7%24322345%48%
1611
16th to endDay
16%7%33423336%44%
1728
February1st to 15thDay
16%6%245%23346%43%
1595
16th to endDay
13%5%25%423346%48%
1608
March1st to 15thDay
13%42331335%7%50%
1969
16th to endDay
16%6%25%43435%5%41%
2112
April1st to 15thDay
11%5%2332345%7%50%
2152
16th to endDay
10%425%5%345%5%6%46%
2160
May1st to 15thDay
12%5%25%446%6%6%8%37%
2198
16th to endDay
9%5%26%5%46%6%7%8%36%
2431
June1st to 15thDay
10%5%25%5%36%6%8%9%35%
2484
16th to endDay
8%425%7%47%7%8%11%32%
2406
July1st to 15thDay
8%426%7%37%8%7%12%28%
2340
16th to endDay
7%5%37%7%47%7%9%10%28%
2465
August1st to 15thDay
11%6%37%7%36%6%8%9%28%
2274
16th to endDay
12%7%36%7%46%6%8%10%25%
2292
September1st to 15thDay
11%6%36%6%35%5%7%8%35%
2160
16th to endDay
17%9%36%6%35%5%5%6%29%
1974
October1st to 15thDay
17%7%2442234445%
1707
16th to endDay
11%414323245%56%
1760
November1st to 15thDay
13%5%14323335%53%
1757
16th to endDay
13%5%24423346%50%
1620
December1st to 15thDay
13%8%345%24445%42%
1440
16th to endDay
17%7%24423445%43%
1641
January1st to 15thNight
12%7%36%5%2345%6%42%
2327
16th to endNight
15%6%34424445%44%
2496
February1st to 15thNight
17%5%24324346%45%
2262
16th to endNight
12%5%24425%45%8%45%
1863
March1st to 15thNight
12%5%1342445%7%49%
1968
16th to endNight
12%6%2442445%6%46%
2112
April1st to 15thNight
10%5%245%2345%6%49%
1796
16th to endNight
9%414425%5%5%8%49%
1800
May1st to 15thNight
8%425%435%5%5%9%43%
1762
16th to endNight
9%4244235%6%10%45%
1682
June1st to 15thNight
8%5%27%5%35%46%10%41%
1470
16th to endNight
7%6%25%435%6%7%12%39%
1545
July1st to 15thNight
6%426%6%47%6%8%12%35%
1620
16th to endNight
6%425%5%36%7%9%13%35%
1703
August1st to 15thNight
6%6%25%6%36%7%7%10%35%
1674
16th to endNight
9%6%25%5%36%6%7%11%34%
1910
September1st to 15thNight
12%314335%5%6%8%44%
1800
16th to endNight
15%7%36%6%3446%6%33%
1981
October1st to 15thNight
14%5%23323436%49%
2051
16th to endNight
10%323323336%57%
2112
November1st to 15thNight
10%5%24323346%53%
2101
16th to endNight
13%5%24323346%49%
2335
December1st to 15thNight
13%6%243245%5%7%42%
2520
16th to endNight
14%6%25%42435%7%41%
2577

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%6%24323445%48%
1611
16th to endDay
16%7%2442245%445%
1728
February1st to 15thDay
16%5%24433447%43%
1595
16th to endDay
13%425%5%24346%48%
1608
March1st to 15thDay
13%423322338%51%
1980
16th to endDay
15%6%25%42445%6%42%
2111
April1st to 15thDay
11%42431335%7%51%
2152
16th to endDay
10%315%5%25%5%5%6%47%
2160
May1st to 15thDay
11%5%25%445%6%6%8%39%
2198
16th to endDay
9%5%15%6%46%5%7%8%38%
2431
June1st to 15thDay
10%425%5%36%6%8%9%36%
2484
16th to endDay
8%425%6%47%7%7%12%33%
2406
July1st to 15thDay
8%425%5%47%8%9%11%30%
2340
16th to endDay
8%5%35%6%37%7%9%10%30%
2465
August1st to 15thDay
12%5%27%6%45%7%7%10%29%
2274
16th to endDay
12%7%36%6%46%7%7%9%27%
2292
September1st to 15thDay
11%6%36%6%35%6%6%8%36%
2160
16th to endDay
18%9%36%6%35%5%5%6%29%
1974
October1st to 15thDay
17%7%25%423335%45%
1707
16th to endDay
11%41441323457%
1760
November1st to 15thDay
13%423323236%54%
1757
16th to endDay
12%424424246%50%
1620
December1st to 15thDay
13%8%45%424447%41%
1440
16th to endDay
17%6%25%332445%44%
1641
January1st to 15thNight
11%7%36%5%335%46%43%
2327
16th to endNight
15%6%2442345%6%44%
2496
February1st to 15thNight
17%6%24324345%45%
2255
16th to endNight
12%425%425%45%7%45%
1863
March1st to 15thNight
12%42432345%7%49%
1980
16th to endNight
12%6%2442346%6%46%
2112
April1st to 15thNight
10%425%42445%6%50%
1796
16th to endNight
9%413435%45%8%49%
1800
May1st to 15thNight
9%4245%35%5%6%9%43%
1761
16th to endNight
9%4244245%6%9%46%
1682
June1st to 15thNight
8%437%5%35%36%10%42%
1470
16th to endNight
9%5%24435%5%7%12%40%
1545
July1st to 15thNight
6%425%6%46%7%7%11%36%
1620
16th to endNight
6%325%5%36%6%9%13%35%
1703
August1st to 15thNight
7%5%36%6%36%6%7%10%36%
1674
16th to endNight
10%5%25%6%35%6%8%11%34%
1910
September1st to 15thNight
11%414435%45%9%43%
1800
16th to endNight
15%7%46%6%345%5%6%34%
1981
October1st to 15thNight
14%5%24313446%49%
2051
16th to endNight
10%413323335%56%
2112
November1st to 15thNight
10%5%23323346%53%
2101
16th to endNight
14%5%24323337%49%
2335
December1st to 15thNight
13%6%244245%5%7%42%
2520
16th to endNight
15%5%25%5%23447%42%
2577

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
39%6%10%15%20%8%
1612
16th to endDay
41%45%17%23%7%
1728
February1st to 15thDay
42%37%19%21%5%
1598
16th to endDay
37%5%9%21%20%5%
1608
March1st to 15thDay
32%5%13%21%19%6%
1980
16th to endDay
42%5%9%17%19%4
2112
April1st to 15thDay
32%5%10%24%20%6%
2152
16th to endDay
34%7%12%19%20%6%
2160
May1st to 15thDay
40%9%14%20%13%1
2198
16th to endDay
39%8%16%23%11%
2435
June1st to 15thDay
39%10%16%20%11%
2484
16th to endDay
40%11%19%19%8%
2406
July1st to 15thDay
39%14%18%18%6%1
2201
16th to endDay
40%12%20%19%6%
2310
August1st to 15thDay
46%11%16%17%8%
2261
16th to endDay
48%11%15%17%5%
2292
September1st to 15thDay
42%11%13%14%13%4
2160
16th to endDay
52%7%11%12%14%2
1974
October1st to 15thDay
41%48%20%22%3
1707
16th to endDay
31%37%21%29%7%
1760
November1st to 15thDay
33%28%17%27%8%
1757
16th to endDay
35%5%8%19%23%8%
1620
December1st to 15thDay
43%5%10%18%15%5%
1440
16th to endDay
42%49%19%17%5%
1641
January1st to 15thNight
41%5%9%14%21%6%
2327
16th to endNight
41%37%20%18%8%
2496
February1st to 15thNight
40%48%15%23%7%
2263
16th to endNight
37%5%9%20%19%6%
1863
March1st to 15thNight
34%5%11%23%19%6%
1980
16th to endNight
36%5%11%21%19%4
2112
April1st to 15thNight
34%5%12%20%21%6%
1796
16th to endNight
31%7%14%22%16%6%
1800
May1st to 15thNight
36%8%16%22%14%1
1762
16th to endNight
32%9%17%26%12%1
1684
June1st to 15thNight
38%7%18%24%10%1
1470
16th to endNight
35%10%20%24%8%
1545
July1st to 15thNight
37%12%20%21%8%
1530
16th to endNight
34%12%22%23%7%
1595
August1st to 15thNight
40%11%19%19%8%
1663
16th to endNight
39%12%17%24%41
1910
September1st to 15thNight
36%11%16%17%15%3
1800
16th to endNight
48%8%11%15%14%1
1981
October1st to 15thNight
36%5%8%21%22%5%
2051
16th to endNight
30%38%21%26%9%
2112
November1st to 15thNight
33%48%16%27%9%
2101
16th to endNight
36%47%19%22%9%
2335
December1st to 15thNight
40%5%11%18%18%5%
2520
16th to endNight
41%5%10%17%18%6%
2577

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%17%45%8%6%
90
16th to endDay
16%36%33%12%1
96
February1st to 15thDay
23%21%41%10%3
112
16th to endDay
15%21%38%19%4
239
March1st to 15thDay
16%13%40%18%9%1
270
16th to endDay
18%13%33%20%11%2
288
April1st to 15thDay
19%15%23%22%12%7%
270
16th to endDay
12%7%31%31%11%6%
270
May1st to 15thDay
13%10%32%28%10%5%
288
16th to endDay
15%317%28%22%12%
331
June1st to 15thDay
11%317%33%23%11%
315
16th to endDay
9%219%32%26%10%
315
July1st to 15thDay
8%13%36%32%8%
305
16th to endDay
12%12%34%28%11%
326
August1st to 15thDay
17%211%29%24%15%
313
16th to endDay
15%111%25%26%20%
332
September1st to 15thDay
17%219%26%16%16%
315
16th to endDay
23%121%25%16%10%
314
October1st to 15thDay
20%6%23%28%15%6%
278
16th to endDay
10%8%23%28%22%6%
272
November1st to 15thDay
16%8%31%24%16%2
265
16th to endDay
12%14%22%29%18%1
222
December1st to 15thDay
21%21%28%15%13%
60
16th to endDay
28%16%23%24%6%1
81
January1st to 15thNight
17%17%29%26%9%
720
16th to endNight
19%14%33%29%3
768
February1st to 15thNight
21%15%33%25%3
704
16th to endNight
14%18%35%25%5%
631
March1st to 15thNight
15%13%38%24%7%
720
16th to endNight
15%10%35%29%8%
768
April1st to 15thNight
12%12%35%28%9%
718
16th to endNight
12%9%35%31%10%
720
May1st to 15thNight
11%6%34%34%11%
682
16th to endNight
12%316%35%28%4
563
June1st to 15thNight
11%19%40%24%4
390
16th to endNight
13%116%41%24%2
465
July1st to 15thNight
7%12%40%33%5%
510
16th to endNight
9%19%36%37%5%
564
August1st to 15thNight
10%12%36%33%7%
593
16th to endNight
13%10%31%34%10%
764
September1st to 15thNight
14%11%36%30%5%
720
16th to endNight
20%219%31%22%4
717
October1st to 15thNight
18%422%27%23%3
684
16th to endNight
13%8%27%27%19%3
704
November1st to 15thNight
13%7%28%31%16%3
700
16th to endNight
16%11%27%26%15%1
720
December1st to 15thNight
18%10%26%29%12%1
720
16th to endNight
18%13%28%29%9%
768
Page generated at 2017-10-07 14:07:52. Version ac04

Copyright 2017 A. Danko


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