Naples
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Naples 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
67%
15904
19%
46583
17%
15866
70%
15866
31%
29261

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
59%
717
19%
2327
17%
716
64%
716
28%
1397
January16th to endNight
56%
768
26%
2385
21%
768
62%
768
32%
1412
February1st to 15thNight
53%
701
25%
2105
20%
700
59%
700
35%
1239
February16th to endNight
67%
631
30%
1807
24%
631
72%
631
42%
996
March1st to 15thNight
64%
720
29%
1980
21%
720
71%
720
47%
1077
March16th to endNight
69%
768
29%
2112
24%
768
72%
768
43%
1194
April1st to 15thNight
72%
718
24%
1976
19%
718
76%
718
47%
1068
April16th to endNight
66%
720
25%
1877
18%
720
70%
720
42%
1114
May1st to 15thNight
82%
641
26%
1721
20%
641
84%
641
51%
927
May16th to endNight
78%
561
17%
1683
15%
561
79%
561
32%
1050
June1st to 15thNight
65%
540
7%
1620
7%
540
65%
540
19%
1195
June16th to endNight
73%
540
7%
1620
6%
540
73%
540
20%
1193
July1st to 15thNight
74%
510
5%
1530
6%
510
74%
510
18%
1176
July16th to endNight
82%
564
6%
1595
7%
531
83%
531
25%
1101
August1st to 15thNight
75%
527
5%
1636
5%
524
75%
524
21%
1165
August16th to endNight
67%
689
3%
1914
3%
689
67%
689
17%
1449
September1st to 15thNight
72%
660
5%
1815
5%
660
72%
660
20%
1342
September16th to endNight
60%
657
4%
1815
5%
657
60%
657
13%
1477
October1st to 15thNight
72%
660
21%
1859
22%
660
73%
660
30%
1200
October16th to endNight
61%
704
22%
2112
22%
704
64%
704
28%
1331
November1st to 15thNight
66%
700
28%
2101
27%
700
70%
700
39%
1179
November16th to endNight
64%
720
28%
2160
26%
720
68%
720
34%
1269
December1st to 15thNight
63%
720
23%
2337
22%
720
67%
720
31%
1349
December16th to endNight
68%
768
24%
2496
26%
768
71%
768
36%
1361

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%6%46%7%8%10%38%
47370
Night
5%425%5%35%5%7%10%43%
46789
TransparencyDay
35%11%18%18%11%3
47071
Night
32%10%18%20%14%3
46592
SeeingDay
7%110%23%31%25%
5741
Night
7%112%31%32%13%
15913

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%5%345%35%5%6%10%42%
1611
16th to endDay
7%425%425%6%6%7%46%
1837
February1st to 15thDay
9%42332345%9%49%
1750
16th to endDay
43233245%6%8%54%
1664
March1st to 15thDay
22133245%6%11%55%
1980
16th to endDay
5%3245%245%5%9%51%
2111
April1st to 15thDay
33134245%6%11%54%
1972
16th to endDay
431442446%9%52%
2082
May1st to 15thDay
3223245%6%10%58%
2238
16th to endDay
7%425%5%36%6%7%10%38%
2431
June1st to 15thDay
10%6%37%7%5%8%8%8%10%23%
2340
16th to endDay
6%5%26%7%5%8%8%10%12%23%
2340
July1st to 15thDay
6%5%47%9%6%9%10%10%11%18%
2340
16th to endDay
5%327%8%6%10%12%13%11%18%
2465
August1st to 15thDay
5%5%36%8%6%9%11%10%10%22%
2220
16th to endDay
6%6%38%9%6%10%8%9%10%19%
1925
September1st to 15thDay
35%38%10%6%8%10%9%11%21%
1815
16th to endDay
9%8%38%9%6%9%8%8%9%18%
1815
October1st to 15thDay
5%426%7%37%7%9%10%35%
1769
16th to endDay
8%426%5%35%6%6%9%40%
1760
November1st to 15thDay
5%423436%5%6%9%49%
1757
16th to endDay
6%3144346%8%7%48%
1800
December1st to 15thDay
8%435%426%6%5%10%42%
1620
16th to endDay
4324435%5%8%9%48%
1728
January1st to 15thNight
7%5%25%5%345%7%10%41%
2327
16th to endNight
6%425%435%46%9%45%
2385
February1st to 15thNight
8%5%3443345%7%49%
2103
16th to endNight
332432445%9%55%
1807
March1st to 15thNight
3314325%35%8%57%
1980
16th to endNight
234425%5%5%8%55%
2112
April1st to 15thNight
321332346%10%57%
1976
16th to endNight
43145%235%5%9%52%
1877
May1st to 15thNight
3122245%7%9%59%
1721
16th to endNight
5%3245%35%5%8%11%42%
1682
June1st to 15thNight
10%6%37%6%37%7%8%12%26%
1620
16th to endNight
5%427%8%47%6%8%12%29%
1620
July1st to 15thNight
45%37%8%5%8%8%9%11%29%
1620
16th to endNight
23246%5%8%9%10%15%32%
1703
August1st to 15thNight
5%426%7%47%7%8%12%32%
1647
16th to endNight
7%5%37%7%47%7%9%13%27%
1914
September1st to 15thNight
4426%7%47%10%11%13%25%
1815
16th to endNight
8%7%39%8%5%7%7%8%11%20%
1815
October1st to 15thNight
5%5%25%5%36%6%6%10%42%
1859
16th to endNight
9%5%25%6%35%5%5%8%42%
2112
November1st to 15thNight
5%42442345%7%52%
2101
16th to endNight
7%4244346%5%9%47%
2160
December1st to 15thNight
6%5%245%25%5%5%8%48%
2337
16th to endNight
5%3244245%6%10%50%
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
33%8%14%24%14%4
1612
16th to endDay
32%6%12%24%18%5%
1837
February1st to 15thDay
29%5%12%23%20%9%
1752
16th to endDay
24%6%14%25%21%7%
1664
March1st to 15thDay
21%6%16%28%22%5%
1980
16th to endDay
26%6%14%25%19%8%
2112
April1st to 15thDay
23%7%20%27%17%3
1972
16th to endDay
26%5%16%25%21%3
2082
May1st to 15thDay
18%7%20%30%18%4
2238
16th to endDay
35%10%20%22%10%
2435
June1st to 15thDay
48%14%22%12%2
2340
16th to endDay
44%18%24%11%1
2340
July1st to 15thDay
51%22%19%6%
2201
16th to endDay
45%23%21%9%
2310
August1st to 15thDay
43%20%26%8%
2207
16th to endDay
50%20%22%5%
1925
September1st to 15thDay
47%20%22%8%1
1815
16th to endDay
54%15%17%9%2
1815
October1st to 15thDay
36%12%17%15%14%3
1769
16th to endDay
36%7%13%17%16%8%
1760
November1st to 15thDay
29%5%13%21%20%8%
1757
16th to endDay
29%8%13%19%18%10%
1800
December1st to 15thDay
36%6%15%19%16%5%
1620
16th to endDay
28%6%17%23%19%5%
1728
January1st to 15thNight
34%8%15%24%13%3
2327
16th to endNight
32%6%12%24%18%5%
2385
February1st to 15thNight
32%5%9%22%20%10%
2112
16th to endNight
24%6%14%24%22%7%
1807
March1st to 15thNight
23%414%31%20%5%
1980
16th to endNight
24%7%13%27%21%6%
2112
April1st to 15thNight
21%6%17%31%18%4
1976
16th to endNight
27%6%14%23%24%4
1877
May1st to 15thNight
18%7%19%29%20%4
1722
16th to endNight
30%11%19%24%14%
1684
June1st to 15thNight
46%12%23%13%3
1620
16th to endNight
42%16%26%12%2
1620
July1st to 15thNight
43%19%26%9%1
1530
16th to endNight
32%18%34%13%
1595
August1st to 15thNight
37%18%31%12%
1636
16th to endNight
43%19%29%7%
1914
September1st to 15thNight
40%18%29%10%1
1815
16th to endNight
51%19%17%9%2
1815
October1st to 15thNight
33%11%17%19%15%3
1859
16th to endNight
38%6%11%18%19%6%
2112
November1st to 15thNight
28%5%12%21%24%7%
2101
16th to endNight
30%7%12%19%20%9%
2160
December1st to 15thNight
32%6%16%22%17%4
2337
16th to endNight
27%7%16%24%21%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
15%427%27%22%2
90
16th to endDay
14%11%25%31%13%4
96
February1st to 15thDay
25%26%36%21%7%
90
16th to endDay
6%324%46%20%
165
March1st to 15thDay
3118%46%26%2
270
16th to endDay
5%219%39%28%4
288
April1st to 15thDay
4122%36%28%5%
270
16th to endDay
7%111%35%38%4
270
May1st to 15thDay
419%33%38%12%
288
16th to endDay
5%1320%39%29%
331
June1st to 15thDay
16%7%12%32%29%
315
16th to endDay
428%29%54%
315
July1st to 15thDay
6%427%60%
305
16th to endDay
8%9%27%53%
326
August1st to 15thDay
7%17%32%50%
297
16th to endDay
11%210%29%45%
268
September1st to 15thDay
41310%32%48%
255
16th to endDay
11%110%37%38%
254
October1st to 15thDay
419%29%38%17%
255
16th to endDay
15%114%30%26%12%
272
November1st to 15thDay
8%111%27%40%10%
265
16th to endDay
4121%34%34%4
270
December1st to 15thDay
24%17%37%27%1
90
16th to endDay
313%30%44%8%
96
January1st to 15thNight
10%417%36%29%1
720
16th to endNight
7%424%41%20%
768
February1st to 15thNight
10%325%40%18%
704
16th to endNight
5%218%50%21%1
631
March1st to 15thNight
5%222%43%24%1
720
16th to endNight
5%118%47%25%1
768
April1st to 15thNight
4215%45%30%2
718
16th to endNight
7%16%41%31%1
720
May1st to 15thNight
47%44%38%4
642
16th to endNight
6%6%28%47%10%
563
June1st to 15thNight
12%1317%45%19%
540
16th to endNight
5%210%40%40%
540
July1st to 15thNight
5%17%39%44%
510
16th to endNight
316%35%52%
564
August1st to 15thNight
8%7%40%42%
527
16th to endNight
9%1311%35%38%
689
September1st to 15thNight
7%1311%39%36%
660
16th to endNight
14%1317%38%24%
657
October1st to 15thNight
9%7%31%39%11%
660
16th to endNight
13%115%32%26%11%
704
November1st to 15thNight
8%116%37%31%4
700
16th to endNight
8%217%40%29%1
720
December1st to 15thNight
9%217%39%28%2
720
16th to endNight
6%215%37%33%3
768
Page generated at 2017-08-13 14:16:42. Version ac04

Copyright 2017 A. Danko


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