Etna
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Etna clear sky chart from 2005-11-06 to 2024-02-10.

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%
23196
20%
80258
19%
23091
59%
23091
27%
49288

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 10thNight
39%
754
9%
4373
10%
736
43%
736
9%
3169
January11th to 20thNight
43%
756
13%
4168
15%
740
47%
740
11%
3011
January21st to endNight
44%
835
12%
4497
20%
814
48%
814
10%
3430
February1st to 10thNight
45%
758
17%
2462
16%
758
49%
758
20%
1636
February11th to 20thNight
43%
701
16%
2274
16%
700
47%
700
22%
1506
February21st to endNight
41%
592
17%
1802
14%
592
45%
592
21%
1228
March1st to 10thNight
34%
720
11%
2016
8%
720
37%
720
17%
1484
March11th to 20thNight
42%
720
15%
1980
11%
720
45%
720
21%
1417
March21st to endNight
33%
792
9%
2160
5%
792
36%
792
17%
1617
April1st to 10thNight
37%
720
13%
1800
6%
720
39%
720
22%
1320
April11th to 20thNight
41%
711
16%
1779
9%
711
43%
711
27%
1226
April21st to endNight
50%
644
16%
1724
8%
644
54%
644
32%
1098
May1st to 10thNight
51%
540
20%
1620
12%
540
56%
540
36%
922
May11th to 20thNight
54%
359
18%
1421
20%
359
58%
359
22%
847
May21st to endNight
55%
388
16%
1552
15%
388
62%
388
23%
889
June1st to 10thNight
61%
360
16%
1440
19%
360
66%
360
25%
824
June11th to 20thNight
61%
360
26%
1440
30%
360
71%
360
42%
637
June21st to endNight
79%
360
30%
1440
43%
360
83%
360
57%
529
July1st to 10thNight
88%
350
29%
1400
42%
350
90%
350
62%
490
July11th to 20thNight
87%
348
35%
1392
47%
348
90%
348
61%
495
July21st to endNight
93%
573
37%
1657
37%
541
94%
541
77%
643
August1st to 10thNight
89%
537
36%
1602
32%
534
90%
534
69%
666
August11th to 20thNight
89%
534
39%
1602
31%
534
91%
534
73%
647
August21st to endNight
81%
782
41%
1970
27%
782
82%
782
77%
901
September1st to 10thNight
82%
720
42%
1800
27%
720
85%
720
80%
809
September11th to 20thNight
76%
720
37%
1809
27%
720
79%
720
63%
922
September21st to endNight
69%
720
32%
2059
29%
720
73%
720
50%
1053
October1st to 10thNight
65%
720
26%
2160
24%
720
72%
720
48%
1094
October11th to 20thNight
67%
720
28%
2160
29%
720
71%
720
42%
1149
October21st to endNight
60%
792
27%
2376
26%
792
64%
792
35%
1362
November1st to 10thNight
48%
740
20%
2333
20%
740
50%
740
22%
1567
November11th to 20thNight
45%
760
14%
2631
13%
760
49%
760
19%
1737
November21st to endNight
47%
760
17%
2660
16%
760
51%
760
23%
1663
December1st to 10thNight
46%
760
18%
2660
16%
760
52%
760
22%
1694
December11th to 20thNight
38%
760
13%
3220
13%
759
43%
759
12%
2390
December21st to endNight
32%
830
9%
4819
13%
817
36%
817
8%
3216

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
45%25%5%35%5%6%7%52%
78360
Night
35%25%5%46%6%6%8%50%
80633
TransparencyDay
32%8%12%19%19%9%
78074
Night
34%10%13%19%17%7%
80440
SeeingDay
12%18%28%27%13%3
13973
Night
7%12%23%33%22%3
23217

By Month

Percentage Cloud Cover SW (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 10thDay
310%48%8%5%7%8%9%9%30%
2539
11th to 20thDay
5%12%49%9%5%6%6%6%8%30%
2768
21st to endDay
37%39%10%6%7%7%8%7%33%
3146
February1st to 10thDay
37%27%6%5%7%9%8%9%38%
1702
11th to 20thDay
37%46%5%46%6%7%8%42%
1575
21st to endDay
49%47%7%47%7%7%8%37%
1453
March1st to 10thDay
39%48%8%5%9%7%7%9%30%
1939
11th to 20thDay
48%38%7%5%7%7%7%8%35%
1980
21st to endDay
5%10%47%8%48%8%7%9%32%
2196
April1st to 10thDay
5%8%47%9%5%6%6%6%9%35%
2160
11th to 20thDay
5%9%47%6%45%5%5%8%41%
2129
21st to endDay
5%7%36%5%45%45%8%48%
2233
May1st to 10thDay
5%6%25%5%25%45%7%53%
2340
11th to 20thDay
6%6%35%5%35%5%5%8%49%
2468
21st to endDay
9%7%25%5%35%5%5%9%45%
2723
June1st to 10thDay
6%6%34435%45%8%52%
2520
11th to 20thDay
4423323347%66%
2520
21st to endDay
321331334474%
2520
July1st to 10thDay
2112213335%76%
2520
11th to 20thDay
211222223479%
2520
21st to endDay
1111223345%78%
2559
August1st to 10thDay
2112223445%74%
2328
11th to 20thDay
112212345%79%
2298
21st to endDay
111111123483%
2386
September1st to 10thDay
111212235%82%
2160
11th to 20thDay
321342445%7%66%
2147
21st to endDay
331322335%7%68%
1900
October1st to 10thDay
5%32342435%5%63%
1800
11th to 20thDay
34135%245%6%7%60%
1800
21st to endDay
5%5%36%5%346%5%7%52%
1980
November1st to 10thDay
5%7%37%7%35%6%7%9%40%
1745
11th to 20thDay
45%347%5%7%7%8%12%36%
1544
21st to endDay
36%36%6%46%7%7%9%43%
1520
December1st to 10thDay
35%36%6%46%7%8%9%41%
1520
11th to 20thDay
5%9%48%9%5%8%7%8%9%27%
1928
21st to endDay
49%39%11%8%9%8%8%9%22%
2794
January1st to 10thNight
46%36%8%5%9%10%10%10%29%
4406
11th to 20thNight
49%49%10%5%8%6%7%8%31%
4194
21st to endNight
49%49%9%6%8%8%6%7%28%
4521
February1st to 10thNight
45%347%47%7%7%12%41%
2462
11th to 20thNight
37%36%7%5%6%6%8%9%42%
2272
21st to endNight
26%36%6%47%7%8%11%40%
1802
March1st to 10thNight
47%37%6%48%8%8%9%35%
2016
11th to 20thNight
46%46%7%48%7%7%9%38%
1980
21st to endNight
27%46%7%48%8%7%11%35%
2160
April1st to 10thNight
47%37%8%46%6%7%10%39%
1800
11th to 20thNight
37%35%5%36%6%7%8%46%
1779
21st to endNight
5%9%25%434348%53%
1724
May1st to 10thNight
4425%5%345%46%58%
1620
11th to 20thNight
46%25%5%37%5%5%8%50%
1421
21st to endNight
6%7%24425%5%5%7%51%
1552
June1st to 10thNight
6%5%245%35%5%6%8%53%
1440
11th to 20thNight
5%322313236%70%
1440
21st to endNight
2112112226%79%
1440
July1st to 10thNight
112113236%79%
1440
11th to 20thNight
211221123480%
1440
21st to endNight
11121222386%
1755
August1st to 10thNight
221212335%81%
1611
11th to 20thNight
111112123483%
1602
21st to endNight
111111133384%
1970
September1st to 10thNight
111111225%85%
1800
11th to 20thNight
221221235%7%71%
1809
21st to endNight
3313323346%69%
2059
October1st to 10thNight
3313423335%70%
2160
11th to 20thNight
32134345%5%7%63%
2160
21st to endNight
35%24435%45%9%57%
2376
November1st to 10thNight
46%26%6%47%7%8%9%41%
2333
11th to 20thNight
45%25%6%5%8%8%9%11%38%
2631
21st to endNight
35%25%5%36%6%6%9%47%
2660
December1st to 10thNight
45%25%6%46%6%8%11%43%
2660
11th to 20thNight
5%8%37%9%5%9%9%7%9%29%
3276
21st to endNight
38%37%7%5%7%8%8%9%33%
4862

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 10thDay
50%15%13%16%41
2539
11th to 20thDay
52%12%10%13%8%5%
2768
21st to endDay
48%12%14%15%8%3
3146
February1st to 10thDay
42%12%14%16%12%4
1702
11th to 20thDay
40%11%13%20%13%3
1584
21st to endDay
47%11%11%17%11%2
1453
March1st to 10thDay
51%11%13%14%9%1
1939
11th to 20thDay
47%11%14%13%13%2
1980
21st to endDay
50%12%16%14%7%2
2196
April1st to 10thDay
48%11%14%15%11%2
2160
11th to 20thDay
43%9%15%18%11%4
2132
21st to endDay
36%8%16%24%15%2
2233
May1st to 10thDay
33%6%13%28%18%2
2340
11th to 20thDay
35%8%13%25%17%2
2471
21st to endDay
37%8%17%25%11%1
2724
June1st to 10thDay
32%8%14%28%17%1
2520
11th to 20thDay
21%7%11%30%25%6%
2520
21st to endDay
15%5%7%27%33%14%
2520
July1st to 10thDay
12%48%23%27%26%
2451
11th to 20thDay
11%37%18%32%29%
2445
21st to endDay
9%46%17%34%31%
2417
August1st to 10thDay
11%5%9%23%36%16%
2312
11th to 20thDay
8%48%18%41%20%
2298
21st to endDay
8%37%21%38%24%
2386
September1st to 10thDay
7%35%16%33%34%
2160
11th to 20thDay
20%6%9%20%33%12%
2147
21st to endDay
17%6%10%24%27%17%
1900
October1st to 10thDay
23%6%13%19%25%15%
1800
11th to 20thDay
24%7%12%22%25%9%
1800
21st to endDay
33%8%10%18%18%12%
1980
November1st to 10thDay
41%9%13%17%16%5%
1745
11th to 20thDay
41%10%17%14%13%5%
1544
21st to endDay
39%11%12%15%16%7%
1520
December1st to 10thDay
40%12%13%14%18%4
1520
11th to 20thDay
53%12%13%11%9%2
1928
21st to endDay
53%15%10%13%6%2
2794
January1st to 10thNight
47%18%13%14%6%2
4406
11th to 20thNight
49%15%11%12%8%5%
4194
21st to endNight
56%11%8%12%10%3
4521
February1st to 10thNight
41%11%14%17%14%4
2462
11th to 20thNight
40%11%13%20%12%3
2274
21st to endNight
40%13%17%16%12%2
1802
March1st to 10thNight
46%13%15%14%12%
2016
11th to 20thNight
44%12%13%16%14%1
1980
21st to endNight
43%17%18%15%6%1
2160
April1st to 10thNight
44%13%17%16%9%2
1800
11th to 20thNight
36%12%19%18%10%5%
1779
21st to endNight
33%9%20%27%9%2
1724
May1st to 10thNight
28%7%17%31%15%2
1620
11th to 20thNight
33%12%15%27%10%2
1421
21st to endNight
33%10%21%26%9%1
1552
June1st to 10thNight
32%10%15%31%11%
1440
11th to 20thNight
19%7%15%37%19%4
1440
21st to endNight
11%5%9%34%34%7%
1440
July1st to 10thNight
8%5%11%24%29%22%
1400
11th to 20thNight
10%47%23%33%24%
1392
21st to endNight
7%25%20%44%23%
1657
August1st to 10thNight
9%48%32%34%13%
1602
11th to 20thNight
7%38%24%42%16%
1602
21st to endNight
7%38%25%38%19%
1970
September1st to 10thNight
5%37%18%35%32%
1800
11th to 20thNight
14%413%23%34%11%
1809
21st to endNight
18%7%10%23%23%19%
2059
October1st to 10thNight
20%6%11%20%28%14%
2160
11th to 20thNight
22%8%12%23%25%10%
2160
21st to endNight
27%9%14%20%19%12%
2376
November1st to 10thNight
39%13%13%15%14%7%
2333
11th to 20thNight
40%12%16%16%12%5%
2631
21st to endNight
36%11%13%16%16%8%
2660
December1st to 10thNight
36%13%12%17%19%4
2660
11th to 20thNight
50%13%9%14%12%1
3276
21st to endNight
45%15%15%15%9%2
4862

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 10thDay
27%28%23%16%5%2
180
11th to 20thDay
20%23%27%18%11%2
317
21st to endDay
16%19%30%21%12%1
407
February1st to 10thDay
16%24%30%21%8%1
368
11th to 20thDay
17%29%25%21%7%
335
21st to endDay
17%29%30%18%5%1
334
March1st to 10thDay
23%29%29%14%5%
420
11th to 20thDay
21%24%27%19%9%
420
21st to endDay
20%30%26%18%5%
462
April1st to 10thDay
20%25%31%18%5%1
420
11th to 20thDay
25%23%26%17%7%2
412
21st to endDay
13%28%29%20%7%3
420
May1st to 10thDay
18%20%29%22%9%2
423
11th to 20thDay
19%21%27%19%11%3
448
21st to endDay
16%16%26%25%14%3
485
June1st to 10thDay
12%19%24%26%14%4
450
11th to 20thDay
11%22%32%24%10%2
450
21st to endDay
311%32%32%18%4
450
July1st to 10thDay
39%31%35%16%5%
446
11th to 20thDay
17%31%37%19%5%
444
21st to endDay
15%24%43%21%6%
487
August1st to 10thDay
2428%37%22%7%
447
11th to 20thDay
110%23%35%22%9%
437
21st to endDay
37%28%36%20%5%
495
September1st to 10thDay
37%29%39%18%4
450
11th to 20thDay
5%14%26%34%18%3
450
21st to endDay
5%14%32%30%17%2
450
October1st to 10thDay
8%17%27%26%20%2
450
11th to 20thDay
12%14%24%28%19%4
450
21st to endDay
11%17%26%27%15%3
495
November1st to 10thDay
14%17%24%29%13%3
341
11th to 20thDay
10%14%30%23%20%2
192
21st to endDay
11%17%28%28%14%1
180
December1st to 10thDay
13%22%27%21%11%7%
180
11th to 20thDay
17%19%26%24%13%1
180
21st to endDay
19%16%27%27%11%
198
January1st to 10thNight
10%18%29%27%13%3
760
11th to 20thNight
10%19%24%26%16%4
760
21st to endNight
9%18%25%30%14%4
836
February1st to 10thNight
10%16%26%33%15%1
758
11th to 20thNight
9%15%29%29%16%2
704
21st to endNight
8%19%28%33%11%1
592
March1st to 10thNight
11%22%28%26%10%3
720
11th to 20thNight
9%20%23%30%15%2
720
21st to endNight
9%23%32%24%10%1
792
April1st to 10thNight
11%15%33%27%14%1
720
11th to 20thNight
9%17%31%25%16%3
711
21st to endNight
9%14%25%31%19%2
644
May1st to 10thNight
7%11%27%31%22%1
540
11th to 20thNight
7%7%27%32%25%2
359
21st to endNight
7%8%23%33%27%1
389
June1st to 10thNight
8%7%19%39%26%1
360
11th to 20thNight
6%5%25%44%19%1
360
21st to endNight
1415%44%36%1
360
July1st to 10thNight
118%50%39%1
350
11th to 20thNight
27%53%36%1
348
21st to endNight
343%50%4
573
August1st to 10thNight
216%37%48%6%
537
11th to 20thNight
216%40%45%6%
534
21st to endNight
1214%41%39%3
782
September1st to 10thNight
1313%42%37%4
720
11th to 20thNight
3415%36%37%6%
720
21st to endNight
5%6%17%34%31%8%
720
October1st to 10thNight
46%21%37%28%4
720
11th to 20thNight
7%8%17%35%29%5%
720
21st to endNight
9%10%18%32%23%8%
792
November1st to 10thNight
9%12%28%29%17%5%
740
11th to 20thNight
9%14%29%31%14%3
760
21st to endNight
7%14%29%29%18%2
760
December1st to 10thNight
10%15%26%31%15%3
760
11th to 20thNight
10%19%27%29%12%3
760
21st to endNight
12%24%28%26%8%2
836
Page generated at 2024-02-07 03:11:54. Version ac07

Copyright 2024 Attilla Danko


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