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 2018-02-22.

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%
16679
19%
48906
17%
16641
70%
16641
31%
30565

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
57%
777
19%
2522
17%
776
62%
776
28%
1506
January16th to endNight
55%
832
25%
2583
20%
832
61%
832
31%
1551
February1st to 15thNight
55%
761
24%
2285
20%
760
60%
760
35%
1342
February16th to endNight
68%
659
32%
1890
27%
659
73%
659
43%
1027
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%
539
5%
1674
6%
536
76%
536
22%
1186
August16th to endNight
67%
752
4%
2089
4%
752
67%
752
18%
1567
September1st to 15thNight
71%
720
5%
1980
5%
720
71%
720
20%
1459
September16th to endNight
62%
717
6%
1980
6%
717
62%
717
15%
1567
October1st to 15thNight
71%
720
20%
2028
21%
720
73%
720
30%
1304
October16th to endNight
60%
768
23%
2304
22%
768
64%
768
28%
1458
November1st to 15thNight
67%
760
28%
2281
26%
760
72%
760
40%
1262
November16th to endNight
65%
780
28%
2340
27%
780
69%
780
34%
1374
December1st to 15thNight
63%
780
24%
2532
23%
780
68%
780
33%
1430
December16th to endNight
70%
832
26%
2704
28%
832
72%
832
38%
1437

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%
49326
Night
5%425%5%35%5%7%10%43%
49112
TransparencyDay
35%11%18%18%12%3
49027
Night
32%10%18%20%14%3
48915
SeeingDay
7%110%24%31%24%
6436
Night
7%112%31%32%13%
16688

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%345%6%10%43%
1746
16th to endDay
7%426%425%6%6%7%45%
1990
February1st to 15thDay
8%42342345%9%49%
1900
16th to endDay
43233245%6%8%55%
1728
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%435%8%6%9%11%10%11%22%
2268
16th to endDay
6%6%37%9%6%10%8%9%10%21%
2101
September1st to 15thDay
45%38%10%6%8%10%9%11%22%
1980
16th to endDay
9%8%37%8%5%9%8%8%9%21%
1980
October1st to 15thDay
5%435%6%37%8%9%10%34%
1930
16th to endDay
8%5%26%5%36%6%6%9%40%
1920
November1st to 15thDay
4323436%5%6%9%49%
1907
16th to endDay
6%3145%346%7%7%48%
1950
December1st to 15thDay
8%424425%6%5%9%45%
1755
16th to endDay
4224425%5%8%10%49%
1872
January1st to 15thNight
7%5%245%345%7%10%42%
2522
16th to endNight
6%436%435%46%9%44%
2583
February1st to 15thNight
7%5%2443345%8%49%
2283
16th to endNight
232432445%9%56%
1890
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%33%
1685
16th to endNight
7%6%36%7%47%6%8%12%28%
2089
September1st to 15thNight
6%426%7%47%9%10%13%26%
1980
16th to endNight
8%7%39%7%5%7%6%8%11%24%
1980
October1st to 15thNight
5%5%25%5%35%6%6%11%42%
2028
16th to endNight
9%5%25%6%35%45%8%41%
2304
November1st to 15thNight
5%42442345%7%54%
2281
16th to endNight
6%424435%6%5%9%47%
2340
December1st to 15thNight
6%5%24425%5%5%7%50%
2532
16th to endNight
5%3244235%6%10%51%
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
33%8%13%24%15%4
1747
16th to endDay
32%7%13%23%18%5%
1990
February1st to 15thDay
29%5%13%23%18%9%
1902
16th to endDay
24%6%13%25%22%7%
1728
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%9%
2255
16th to endDay
49%19%22%7%
2101
September1st to 15thDay
47%20%22%8%1
1980
16th to endDay
51%15%19%10%2
1980
October1st to 15thDay
36%13%17%15%13%3
1930
16th to endDay
36%7%13%16%16%8%
1920
November1st to 15thDay
28%5%13%22%21%7%
1907
16th to endDay
28%8%13%19%19%10%
1950
December1st to 15thDay
34%6%15%20%17%5%
1755
16th to endDay
26%6%18%25%18%4
1872
January1st to 15thNight
33%7%16%25%13%2
2522
16th to endNight
33%6%12%23%17%5%
2583
February1st to 15thNight
32%5%10%23%18%9%
2292
16th to endNight
23%6%13%23%24%8%
1890
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
36%18%31%13%
1674
16th to endNight
43%18%28%8%
2089
September1st to 15thNight
40%17%29%10%1
1980
16th to endNight
48%18%18%11%2
1980
October1st to 15thNight
32%11%18%19%14%2
2028
16th to endNight
38%6%11%18%18%6%
2304
November1st to 15thNight
27%5%12%23%24%7%
2281
16th to endNight
30%7%12%19%21%8%
2340
December1st to 15thNight
31%6%15%23%18%5%
2532
16th to endNight
25%6%17%26%20%3
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
14%5%30%28%19%1
135
16th to endDay
11%8%23%41%11%3
144
February1st to 15thDay
2319%41%25%7%
135
16th to endDay
5%221%42%23%4
185
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%
313
16th to endDay
12%210%31%42%
332
September1st to 15thDay
6%138%31%47%
315
16th to endDay
10%10%37%39%
314
October1st to 15thDay
410%28%39%17%
315
16th to endDay
14%215%30%25%11%
336
November1st to 15thDay
7%19%28%41%10%
325
16th to endDay
319%36%35%3
330
December1st to 15thDay
17%111%37%25%5%
135
16th to endDay
29%27%45%15%
144
January1st to 15thNight
10%5%18%36%28%1
780
16th to endNight
7%425%41%19%
832
February1st to 15thNight
9%324%41%20%1
764
16th to endNight
5%218%48%23%1
659
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%
539
16th to endNight
10%1311%36%36%
752
September1st to 15thNight
8%1311%38%36%
720
16th to endNight
13%317%40%24%
717
October1st to 15thNight
9%7%31%39%11%
720
16th to endNight
12%116%33%25%10%
768
November1st to 15thNight
7%116%38%31%4
760
16th to endNight
8%217%40%29%1
780
December1st to 15thNight
8%217%39%28%3
780
16th to endNight
5%214%37%35%4
832
Page generated at 2018-02-23 11:21:37. Version ac04

Copyright 2018 A. Danko


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