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 2018-01-20.

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%
15145
13%
48479
8%
15116
37%
15116
17%
34573

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
18%
780
8%
2716
4%
776
24%
776
9%
2137
January16th to endNight
21%
788
10%
2756
5%
788
28%
788
11%
2065
February1st to 15thNight
20%
702
8%
2299
5%
701
26%
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
29%
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
41%
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
43%
360
9%
1440
11%
360
49%
360
20%
900
July1st to 15thNight
51%
340
15%
1360
21%
340
56%
340
25%
774
July16th to endNight
53%
376
12%
1418
15%
354
57%
354
24%
823
August1st to 15thNight
53%
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
52%
720
29%
1244
September16th to endNight
51%
717
22%
1962
15%
717
55%
717
31%
1250
October1st to 15thNight
35%
720
18%
2130
10%
720
44%
720
22%
1449
October16th to endNight
25%
768
11%
2451
7%
768
31%
768
14%
1809
November1st to 15thNight
26%
760
15%
2472
10%
760
34%
760
15%
1775
November16th to endNight
22%
780
12%
2724
7%
780
29%
780
11%
2029
December1st to 15thNight
17%
780
8%
2730
3%
780
22%
780
9%
2157
December16th to endNight
13%
832
9%
2912
3%
832
20%
832
8%
2312

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%
49059
Night
18%9%36%5%34446%31%
48648
Cloud CoverDay
17%8%36%5%3445%7%33%
49068
Night
18%9%46%5%34446%31%
48654
TransparencyDay
49%5%12%20%10%1
48746
Night
53%411%19%9%1
48479
SeeingDay
21%8%25%24%14%4
5913
Night
23%8%28%27%10%
15148

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%15%5%8%6%35%43421%
1552
16th to endDay
13%14%5%8%6%45%46%7%24%
1572
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
12%424423347%49%
1997
October1st to 15thDay
19%7%35%5%34446%35%
1827
16th to endDay
22%9%36%5%35%45%6%27%
1773
November1st to 15thDay
16%9%45%5%3446%7%31%
1716
16th to endDay
21%9%38%6%345%46%26%
1566
December1st to 15thDay
23%13%5%8%5%25%5%5%6%17%
1560
16th to endDay
25%13%5%8%5%34445%18%
1664
January1st to 15thNight
18%16%5%8%7%45%345%20%
2716
16th to endNight
14%14%6%8%7%35%345%25%
2756
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
17%42332335%6%46%
1962
October1st to 15thNight
17%7%35%5%24446%37%
2130
16th to endNight
24%6%46%6%44345%29%
2451
November1st to 15thNight
21%7%37%5%34445%32%
2472
16th to endNight
21%11%47%6%3444427%
2724
December1st to 15thNight
22%15%5%7%5%2444421%
2730
16th to endNight
24%16%47%5%33335%20%
2912

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%34421%
1552
16th to endDay
13%15%39%6%45%45%7%24%
1572
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
12%5%24434347%48%
1997
October1st to 15thDay
19%8%25%4345%5%6%34%
1827
16th to endDay
22%10%36%5%3345%5%28%
1773
November1st to 15thDay
16%9%45%5%35%45%8%30%
1716
16th to endDay
21%9%48%6%245%47%25%
1566
December1st to 15thDay
23%14%48%6%35%5%5%6%15%
1560
16th to endDay
25%15%48%5%3444418%
1664
January1st to 15thNight
17%17%5%9%6%35%5%4420%
2716
16th to endNight
14%15%5%8%7%35%445%25%
2756
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
17%314423446%46%
1962
October1st to 15thNight
17%8%35%424445%37%
2130
16th to endNight
23%8%37%6%34336%28%
2451
November1st to 15thNight
21%8%36%6%25%44431%
2472
16th to endNight
21%11%5%7%6%2444427%
2724
December1st to 15thNight
22%15%6%7%5%24445%20%
2730
16th to endNight
24%16%5%8%6%24435%20%
2912

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
65%5%9%13%5%
1553
16th to endDay
58%413%15%6%
1572
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
35%412%33%12%
1997
October1st to 15thDay
48%6%12%23%9%
1827
16th to endDay
57%414%17%5%
1773
November1st to 15thDay
51%5%15%19%8%
1716
16th to endDay
59%412%15%6%
1566
December1st to 15thDay
66%7%11%11%2
1560
16th to endDay
67%411%10%6%
1664
January1st to 15thNight
65%411%13%4
2716
16th to endNight
60%410%15%7%
2756
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
37%5%11%30%14%
1962
October1st to 15thNight
47%411%25%10%
2130
16th to endNight
57%413%17%5%
2451
November1st to 15thNight
54%412%17%8%2
2472
16th to endNight
60%412%17%5%
2724
December1st to 15thNight
65%412%14%2
2730
16th to endNight
67%310%11%6%
2912

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
24%17%20%28%7%1
90
16th to endDay
38%8%26%21%22
73
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
12%7%22%20%25%10%
314
October1st to 15thDay
21%7%24%21%18%5%
315
16th to endDay
28%10%26%25%9%
299
November1st to 15thDay
23%12%28%21%12%1
280
16th to endDay
31%14%23%22%7%
96
December1st to 15thDay
26%5%33%26%6%1
90
16th to endDay
37%15%30%14%2
96
January1st to 15thNight
26%12%30%25%5%
780
16th to endNight
23%11%34%22%7%
788
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%21%28%23%2
717
October1st to 15thNight
21%8%26%29%14%
720
16th to endNight
28%9%30%25%6%
768
November1st to 15thNight
26%10%28%23%10%
760
16th to endNight
26%12%29%18%11%
780
December1st to 15thNight
33%12%28%21%4
780
16th to endNight
33%11%31%18%31
832
Page generated at 2018-01-21 12:19:22. Version ac04

Copyright 2018 A. Danko


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