Optiques Fullum
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Optiques Fullum clear sky chart from 2005-11-05 to 2017-09-16.

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
31%
14641
13%
46826
8%
14612
37%
14612
17%
33403

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
19%
720
8%
2506
4%
716
24%
716
9%
1971
January16th to endNight
21%
768
10%
2688
5%
768
28%
768
12%
1999
February1st to 15thNight
19%
702
8%
2299
5%
701
24%
701
10%
1813
February16th to endNight
24%
631
13%
1896
6%
631
32%
631
14%
1411
March1st to 15thNight
22%
720
13%
2160
8%
720
28%
720
14%
1618
March16th to endNight
31%
768
19%
1992
10%
768
38%
768
24%
1411
April1st to 15thNight
28%
718
16%
1796
5%
718
34%
718
21%
1334
April16th to endNight
30%
633
16%
1713
6%
633
37%
633
22%
1214
May1st to 15thNight
32%
386
17%
1466
15%
386
42%
386
17%
978
May16th to endNight
36%
374
12%
1497
12%
374
44%
374
17%
972
June1st to 15thNight
37%
360
8%
1440
10%
360
44%
360
14%
1009
June16th to endNight
44%
360
9%
1440
11%
360
50%
360
20%
900
July1st to 15thNight
52%
340
14%
1360
21%
340
58%
340
25%
774
July16th to endNight
53%
376
12%
1418
15%
354
57%
354
24%
823
August1st to 15thNight
52%
371
15%
1442
16%
369
56%
369
23%
856
August16th to endNight
54%
761
20%
1907
11%
761
57%
761
36%
1233
September1st to 15thNight
51%
720
15%
1800
8%
720
53%
720
29%
1244
September16th to endNight
48%
661
20%
1808
13%
661
52%
661
30%
1165
October1st to 15thNight
34%
660
18%
1952
10%
660
43%
660
21%
1342
October16th to endNight
25%
704
10%
2247
6%
704
31%
704
13%
1673
November1st to 15thNight
26%
700
15%
2277
11%
700
34%
700
15%
1640
November16th to endNight
22%
720
12%
2514
7%
720
29%
720
11%
1874
December1st to 15thNight
18%
720
8%
2520
3%
720
23%
720
9%
1998
December16th to endNight
13%
768
9%
2688
3%
768
19%
768
8%
2151

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
17%7%36%5%3445%7%33%
47944
Night
18%9%36%5%34446%31%
46995
Cloud CoverDay
17%8%36%5%3445%7%33%
47953
Night
18%9%46%5%34446%31%
47001
TransparencyDay
49%5%12%20%10%1
47631
Night
53%411%19%9%1
46826
SeeingDay
21%8%26%25%14%4
5568
Night
23%8%27%27%10%
14644

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
21%14%5%7%6%35%435%21%
1432
16th to endDay
13%14%5%8%6%45%46%7%24%
1536
February1st to 15thDay
14%12%5%9%7%46%5%45%23%
1563
16th to endDay
16%12%49%6%25%445%27%
1575
March1st to 15thDay
17%9%48%7%45%445%28%
1790
16th to endDay
18%7%25%434346%38%
2229
April1st to 15thDay
21%7%45%5%34445%32%
2152
16th to endDay
19%6%345%2445%5%38%
2245
May1st to 15thDay
20%5%25%6%35%446%34%
2496
16th to endDay
18%6%345%3345%7%36%
2618
June1st to 15thDay
22%6%25%5%34447%32%
2520
16th to endDay
17%5%26%6%36%5%5%8%32%
2520
July1st to 15thDay
11%425%5%35%5%6%8%40%
2520
16th to endDay
11%425%5%35%6%7%10%37%
2654
August1st to 15thDay
11%6%26%6%35%46%8%36%
2498
16th to endDay
9%3134245%7%9%46%
2292
September1st to 15thDay
15%5%245%23447%43%
2160
16th to endDay
13%5%2442435%7%46%
1841
October1st to 15thDay
20%7%35%4345%46%35%
1675
16th to endDay
22%9%46%6%35%45%6%25%
1625
November1st to 15thDay
15%10%46%5%3446%7%32%
1581
16th to endDay
21%10%38%5%34446%27%
1446
December1st to 15thDay
24%13%5%8%5%25%5%5%5%17%
1440
16th to endDay
26%13%5%7%5%33445%18%
1536
January1st to 15thNight
17%15%5%8%7%45%345%20%
2506
16th to endNight
14%14%5%8%7%35%345%26%
2688
February1st to 15thNight
13%13%5%11%8%46%5%5%5%20%
2297
16th to endNight
16%11%5%9%6%34346%27%
1896
March1st to 15thNight
19%10%47%7%34345%28%
2147
16th to endNight
18%9%35%42334439%
1992
April1st to 15thNight
26%7%35%433345%31%
1796
16th to endNight
22%7%24423436%37%
1713
May1st to 15thNight
21%7%45%5%24346%35%
1466
16th to endNight
19%5%46%425%446%36%
1495
June1st to 15thNight
23%7%36%435%5%5%7%29%
1440
16th to endNight
15%6%24425%5%7%8%36%
1440
July1st to 15thNight
10%325%5%35%5%7%9%41%
1440
16th to endNight
11%5%24435%5%7%9%41%
1514
August1st to 15thNight
10%6%25%5%145%5%10%40%
1452
16th to endNight
12%32442436%7%47%
1907
September1st to 15thNight
15%6%25%6%23346%42%
1800
16th to endNight
18%423433345%46%
1808
October1st to 15thNight
18%7%35%5%24446%36%
1952
16th to endNight
25%6%46%6%43345%28%
2247
November1st to 15thNight
20%8%47%5%345%45%31%
2277
16th to endNight
21%10%47%6%3444427%
2514
December1st to 15thNight
23%15%5%7%5%24445%20%
2520
16th to endNight
25%17%47%5%34335%19%
2688

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
21%14%5%7%7%25%35%421%
1432
16th to endDay
13%15%39%6%45%45%7%24%
1536
February1st to 15thDay
14%12%5%9%7%46%5%5%5%23%
1563
16th to endDay
17%12%5%8%6%24445%27%
1575
March1st to 15thDay
17%10%5%8%6%35%445%27%
1800
16th to endDay
19%6%345%24446%38%
2228
April1st to 15thDay
20%7%35%6%34445%32%
2152
16th to endDay
19%6%25%5%2435%6%38%
2245
May1st to 15thDay
20%5%35%5%35%45%6%34%
2496
16th to endDay
18%6%35%5%3445%7%36%
2618
June1st to 15thDay
22%6%245%3445%6%32%
2520
16th to endDay
16%5%26%5%36%46%8%33%
2520
July1st to 15thDay
11%5%25%435%5%6%8%40%
2520
16th to endDay
12%4245%35%5%7%9%37%
2654
August1st to 15thDay
11%6%35%6%35%5%6%9%35%
2498
16th to endDay
9%3135%245%7%9%47%
2292
September1st to 15thDay
15%5%2443335%7%43%
2160
16th to endDay
13%5%24434347%46%
1841
October1st to 15thDay
19%8%25%4345%5%6%34%
1675
16th to endDay
23%11%36%6%3345%5%26%
1625
November1st to 15thDay
15%10%45%436%45%8%31%
1581
16th to endDay
21%10%38%5%24446%26%
1446
December1st to 15thDay
23%14%48%6%35%5%5%6%15%
1440
16th to endDay
26%15%5%7%6%3444417%
1536
January1st to 15thNight
17%16%5%9%6%35%5%45%20%
2506
16th to endNight
14%15%5%8%6%35%445%26%
2688
February1st to 15thNight
14%13%5%12%8%46%445%20%
2290
16th to endNight
16%12%5%8%6%44446%27%
1896
March1st to 15thNight
21%9%47%7%3434428%
2160
16th to endNight
18%10%35%423345%38%
1992
April1st to 15thNight
25%7%35%434345%31%
1796
16th to endNight
22%7%25%5%24345%36%
1713
May1st to 15thNight
21%7%35%5%33346%35%
1466
16th to endNight
19%5%45%6%34446%35%
1495
June1st to 15thNight
23%7%36%42446%7%28%
1440
16th to endNight
15%6%24425%6%6%8%36%
1440
July1st to 15thNight
10%4145%45%5%7%8%41%
1440
16th to endNight
11%5%245%25%5%6%9%42%
1514
August1st to 15thNight
11%6%345%245%5%10%40%
1452
16th to endNight
12%41442435%7%47%
1907
September1st to 15thNight
15%5%25%5%24345%42%
1800
16th to endNight
18%314423446%46%
1808
October1st to 15thNight
18%8%35%424445%36%
1952
16th to endNight
24%8%37%6%34335%27%
2247
November1st to 15thNight
20%8%36%6%25%445%31%
2277
16th to endNight
21%10%5%7%6%2444426%
2514
December1st to 15thNight
23%15%6%7%5%24445%20%
2520
16th to endNight
24%17%5%7%5%2443419%
2688

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
64%5%10%13%5%
1433
16th to endDay
58%413%15%7%
1536
February1st to 15thDay
61%412%17%3
1565
16th to endDay
58%412%14%9%1
1575
March1st to 15thDay
58%313%15%7%1
1800
16th to endDay
46%411%19%14%3
2229
April1st to 15thDay
53%37%20%11%2
2152
16th to endDay
46%49%20%14%4
2245
May1st to 15thDay
50%49%18%14%1
2496
16th to endDay
46%5%12%21%12%1
2622
June1st to 15thDay
50%6%10%20%11%
2520
16th to endDay
47%6%12%22%9%1
2520
July1st to 15thDay
37%7%14%28%12%
2371
16th to endDay
39%7%17%26%8%
2487
August1st to 15thDay
42%7%17%23%8%
2484
16th to endDay
30%7%18%30%12%
2292
September1st to 15thDay
39%5%13%27%13%
2160
16th to endDay
37%412%32%11%
1841
October1st to 15thDay
49%6%12%22%9%
1675
16th to endDay
58%414%16%5%
1625
November1st to 15thDay
50%5%15%19%9%
1581
16th to endDay
58%412%16%6%
1446
December1st to 15thDay
66%7%11%11%2
1440
16th to endDay
67%412%9%5%
1536
January1st to 15thNight
65%411%13%4
2506
16th to endNight
59%411%15%8%
2688
February1st to 15thNight
65%410%15%4
2299
16th to endNight
58%311%16%9%
1896
March1st to 15thNight
58%49%17%8%1
2160
16th to endNight
49%39%18%14%4
1992
April1st to 15thNight
55%27%19%13%1
1796
16th to endNight
49%37%19%15%4
1713
May1st to 15thNight
51%36%17%16%4
1466
16th to endNight
47%5%11%19%14%1
1497
June1st to 15thNight
53%5%10%19%9%
1440
16th to endNight
42%7%15%20%13%
1440
July1st to 15thNight
34%7%13%29%15%
1360
16th to endNight
36%6%17%24%13%
1418
August1st to 15thNight
38%6%19%22%11%
1442
16th to endNight
36%414%29%13%
1907
September1st to 15thNight
43%410%26%13%
1800
16th to endNight
39%5%11%29%14%
1808
October1st to 15thNight
48%411%24%10%
1952
16th to endNight
58%412%17%6%
2247
November1st to 15thNight
54%5%13%16%8%2
2277
16th to endNight
60%412%17%5%
2514
December1st to 15thNight
66%412%14%2
2520
16th to endNight
68%311%11%5%
2688

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%21%20%25%10%1
60
16th to endDay
42%7%25%18%33
64
February1st to 15thDay
28%13%43%12%2
88
16th to endDay
26%8%33%26%4
234
March1st to 15thDay
22%12%35%22%7%
270
16th to endDay
27%8%27%22%11%2
288
April1st to 15thDay
29%11%28%19%8%2
270
16th to endDay
20%10%29%20%14%4
270
May1st to 15thDay
26%9%26%20%12%4
288
16th to endDay
20%9%30%20%16%3
331
June1st to 15thDay
27%7%21%28%11%3
315
16th to endDay
19%427%30%16%1
315
July1st to 15thDay
13%424%30%19%6%
305
16th to endDay
14%317%34%22%6%
326
August1st to 15thDay
15%318%35%19%7%
313
16th to endDay
10%420%29%20%14%
332
September1st to 15thDay
16%6%21%22%19%13%
315
16th to endDay
14%9%24%20%21%9%
257
October1st to 15thDay
21%9%22%24%16%5%
255
16th to endDay
29%10%25%26%7%
247
November1st to 15thDay
22%11%31%20%11%2
235
16th to endDay
33%10%24%22%9%
66
December1st to 15thDay
28%5%33%30%11
60
16th to endDay
40%12%32%14%
64
January1st to 15thNight
26%13%30%25%5%
720
16th to endNight
23%11%34%22%8%
768
February1st to 15thNight
21%9%36%25%6%
704
16th to endNight
22%10%32%29%6%
631
March1st to 15thNight
26%10%32%25%5%
720
16th to endNight
23%6%30%29%8%1
768
April1st to 15thNight
27%9%27%30%5%
718
16th to endNight
25%9%30%22%10%
633
May1st to 15thNight
24%6%27%28%11%1
386
16th to endNight
21%329%32%12%
375
June1st to 15thNight
28%422%34%9%
360
16th to endNight
17%5%27%34%13%1
360
July1st to 15thNight
10%324%39%20%1
340
16th to endNight
12%224%41%17%1
376
August1st to 15thNight
15%218%40%21%1
371
16th to endNight
15%221%35%23%2
761
September1st to 15thNight
18%318%38%17%2
720
16th to endNight
19%5%22%28%22%1
661
October1st to 15thNight
21%9%26%28%13%
660
16th to endNight
29%9%29%25%6%
704
November1st to 15thNight
26%10%29%23%10%
700
16th to endNight
26%13%27%18%12%
720
December1st to 15thNight
33%12%27%21%4
720
16th to endNight
34%11%30%17%31
768
Page generated at 2017-09-17 12:05:46. Version ac04

Copyright 2017 A. Danko


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