Univerciel
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Univerciel 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%
15140
14%
48493
8%
15108
38%
15108
17%
34621

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
3%
776
24%
776
8%
2190
January16th to endNight
22%
788
10%
2717
6%
788
28%
788
11%
2051
February1st to 15thNight
20%
704
11%
2287
4%
701
28%
701
11%
1763
February16th to endNight
23%
631
14%
1946
7%
631
33%
631
14%
1469
March1st to 15thNight
20%
720
14%
2106
7%
720
28%
720
15%
1588
March16th to endNight
31%
768
21%
2028
10%
768
39%
768
22%
1407
April1st to 15thNight
25%
718
15%
1796
5%
718
30%
718
21%
1324
April16th to endNight
30%
639
17%
1719
7%
639
37%
639
22%
1209
May1st to 15thNight
34%
360
17%
1440
15%
360
43%
360
16%
957
May16th to endNight
34%
375
13%
1497
10%
374
46%
374
19%
959
June1st to 15thNight
38%
360
9%
1440
10%
360
47%
360
16%
968
June16th to endNight
44%
360
8%
1440
11%
360
49%
360
18%
914
July1st to 15thNight
56%
340
14%
1360
20%
340
61%
340
25%
774
July16th to endNight
57%
376
13%
1418
17%
354
60%
354
26%
806
August1st to 15thNight
53%
431
14%
1502
13%
429
57%
429
23%
941
August16th to endNight
56%
713
20%
1859
11%
713
60%
713
35%
1168
September1st to 15thNight
47%
720
15%
1800
7%
720
50%
720
27%
1257
September16th to endNight
48%
717
23%
1956
16%
717
53%
717
31%
1246
October1st to 15thNight
35%
720
17%
2160
11%
720
44%
720
21%
1484
October16th to endNight
27%
768
12%
2407
7%
768
34%
768
14%
1805
November1st to 15thNight
30%
760
16%
2527
11%
760
38%
760
16%
1780
November16th to endNight
20%
780
10%
2730
7%
780
27%
780
10%
2086
December1st to 15thNight
20%
780
8%
2730
4%
780
25%
780
9%
2171
December16th to endNight
15%
832
11%
2912
4%
832
24%
832
9%
2304

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
18%8%36%5%35%45%6%32%
49036
Night
18%9%36%5%34445%33%
48662
Cloud CoverDay
19%7%36%5%3445%6%33%
49045
Night
19%9%36%5%34445%34%
48668
TransparencyDay
51%6%12%19%9%1
48723
Night
52%5%11%19%9%
48493
SeeingDay
22%10%27%23%12%3
5819
Night
23%9%28%27%10%
15140

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
23%14%5%8%5%3443421%
1552
16th to endDay
15%14%5%9%6%35%445%25%
1608
February1st to 15thDay
13%12%5%12%7%45%445%25%
1575
16th to endDay
17%13%5%8%7%4344425%
1527
March1st to 15thDay
17%10%47%6%45%5%45%27%
1841
16th to endDay
16%6%35%5%25%35%5%39%
2194
April1st to 15thDay
24%9%35%424335%33%
2152
16th to endDay
21%7%26%5%24435%36%
2248
May1st to 15thDay
21%7%35%5%24346%32%
2511
16th to endDay
19%6%35%5%35%45%6%33%
2618
June1st to 15thDay
22%5%26%6%35%46%7%30%
2520
16th to endDay
19%5%25%436%6%6%6%32%
2520
July1st to 15thDay
14%4245%35%5%7%8%37%
2520
16th to endDay
13%5%26%435%5%6%8%36%
2654
August1st to 15thDay
12%5%246%45%5%6%8%37%
2446
16th to endDay
12%415%5%245%5%8%43%
2330
September1st to 15thDay
17%415%5%3445%7%41%
2160
16th to endDay
16%424423346%47%
2004
October1st to 15thDay
22%6%26%434445%34%
1800
16th to endDay
27%7%36%6%34445%26%
1815
November1st to 15thDay
16%9%36%5%345%5%6%32%
1657
16th to endDay
25%11%37%5%35%445%24%
1560
December1st to 15thDay
22%13%5%9%6%36%45%5%19%
1560
16th to endDay
23%16%46%6%35%43421%
1664
January1st to 15thNight
20%16%5%9%6%4434420%
2716
16th to endNight
13%15%6%8%6%35%435%27%
2717
February1st to 15thNight
13%12%6%11%7%45%5%4425%
2285
16th to endNight
17%12%47%6%345%4429%
1946
March1st to 15thNight
19%10%5%8%6%3443430%
2093
16th to endNight
15%8%35%5%3334441%
2028
April1st to 15thNight
24%7%33433435%36%
1796
16th to endNight
19%7%34434346%37%
1719
May1st to 15thNight
23%6%25%423446%35%
1440
16th to endNight
17%5%35%5%245%5%5%38%
1495
June1st to 15thNight
19%5%25%6%346%5%7%34%
1440
16th to endNight
16%5%15%435%5%6%7%37%
1440
July1st to 15thNight
11%2234245%5%8%47%
1440
16th to endNight
9%4245%245%6%8%45%
1514
August1st to 15thNight
12%425%5%25%5%6%8%41%
1512
16th to endNight
10%32443445%7%50%
1859
September1st to 15thNight
15%5%16%6%24445%43%
1800
16th to endNight
17%324413235%49%
1956
October1st to 15thNight
21%6%145%25%346%37%
2160
16th to endNight
25%7%35%6%34435%29%
2407
November1st to 15thNight
21%6%26%5%3345%5%33%
2527
16th to endNight
23%10%47%6%34345%25%
2730
December1st to 15thNight
22%15%46%5%34445%21%
2730
16th to endNight
23%15%5%8%6%3434422%
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
23%14%5%7%6%245%3420%
1552
16th to endDay
14%15%5%7%6%36%446%25%
1608
February1st to 15thDay
14%13%411%6%45%446%24%
1575
16th to endDay
18%12%5%8%6%34446%25%
1527
March1st to 15thDay
21%8%37%6%35%43430%
1851
16th to endDay
19%6%2442334440%
2193
April1st to 15thDay
23%9%35%424335%35%
2152
16th to endDay
20%7%36%424435%37%
2248
May1st to 15thDay
24%7%36%424445%32%
2511
16th to endDay
23%5%26%5%3445%6%33%
2618
June1st to 15thDay
21%6%25%6%3445%6%33%
2520
16th to endDay
17%5%25%435%5%6%7%35%
2520
July1st to 15thDay
13%5%25%435%6%8%8%37%
2520
16th to endDay
12%5%36%5%35%5%7%9%36%
2654
August1st to 15thDay
17%425%5%35%45%7%37%
2446
16th to endDay
17%31442445%7%43%
2330
September1st to 15thDay
16%425%5%34447%41%
2160
16th to endDay
15%414423347%46%
2004
October1st to 15thDay
21%7%26%434445%35%
1800
16th to endDay
26%7%36%5%34445%27%
1815
November1st to 15thDay
17%8%36%43445%6%34%
1657
16th to endDay
24%10%36%5%24435%26%
1560
December1st to 15thDay
22%13%5%9%6%35%445%19%
1560
16th to endDay
23%15%5%7%6%35%33420%
1664
January1st to 15thNight
20%16%5%9%6%4434419%
2716
16th to endNight
13%15%5%8%7%35%435%26%
2717
February1st to 15thNight
14%12%6%11%7%35%44424%
2278
16th to endNight
18%12%48%6%345%4428%
1946
March1st to 15thNight
22%9%46%5%3433332%
2106
16th to endNight
18%7%25%42333443%
2028
April1st to 15thNight
24%7%33424435%36%
1796
16th to endNight
19%8%345%23436%38%
1719
May1st to 15thNight
24%6%35%414436%36%
1440
16th to endNight
18%6%344245%6%5%38%
1495
June1st to 15thNight
18%5%35%5%245%5%6%35%
1440
16th to endNight
15%5%16%425%5%6%8%38%
1440
July1st to 15thNight
11%324425%5%5%8%46%
1440
16th to endNight
9%4345%345%7%8%44%
1514
August1st to 15thNight
14%42442446%8%41%
1512
16th to endNight
13%32333435%5%50%
1859
September1st to 15thNight
15%5%245%34446%42%
1800
16th to endNight
17%324422235%49%
1956
October1st to 15thNight
20%6%24425%446%38%
2160
16th to endNight
24%8%36%5%34446%28%
2407
November1st to 15thNight
21%7%36%433345%35%
2527
16th to endNight
22%10%47%6%34435%29%
2730
December1st to 15thNight
22%15%5%7%5%3444421%
2730
16th to endNight
24%15%5%7%6%3334421%
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
67%48%12%5%
1553
16th to endDay
61%5%11%12%7%
1608
February1st to 15thDay
60%5%12%16%4
1577
16th to endDay
60%5%10%14%9%1
1527
March1st to 15thDay
58%5%11%15%7%1
1851
16th to endDay
45%49%18%15%5%
2194
April1st to 15thDay
53%38%18%13%2
2152
16th to endDay
51%36%19%14%3
2248
May1st to 15thDay
52%5%7%19%13%2
2511
16th to endDay
49%6%11%18%11%1
2622
June1st to 15thDay
52%6%11%20%8%
2520
16th to endDay
48%7%13%19%9%
2520
July1st to 15thDay
39%9%13%26%11%
2371
16th to endDay
43%7%17%20%9%
2487
August1st to 15thDay
43%8%15%22%9%
2432
16th to endDay
36%7%17%28%9%
2330
September1st to 15thDay
42%5%12%27%11%
2160
16th to endDay
37%6%13%32%9%
2004
October1st to 15thDay
50%5%12%21%9%
1800
16th to endDay
59%6%13%14%5%
1815
November1st to 15thDay
50%6%14%19%8%
1657
16th to endDay
61%6%12%13%5%
1560
December1st to 15thDay
67%6%11%12%2
1560
16th to endDay
67%5%8%12%6%
1664
January1st to 15thNight
67%5%9%11%4
2716
16th to endNight
60%5%10%16%7%
2717
February1st to 15thNight
62%410%17%5%
2287
16th to endNight
58%5%8%18%9%
1946
March1st to 15thNight
59%39%18%8%1
2106
16th to endNight
46%48%20%15%4
2028
April1st to 15thNight
51%48%18%16%1
1796
16th to endNight
48%48%17%17%3
1719
May1st to 15thNight
49%5%6%18%15%4
1440
16th to endNight
44%6%12%20%13%2
1497
June1st to 15thNight
49%6%11%22%8%1
1440
16th to endNight
43%7%13%19%14%
1440
July1st to 15thNight
33%8%12%29%15%
1360
16th to endNight
34%7%16%26%15%
1418
August1st to 15thNight
37%9%17%23%11%
1502
16th to endNight
32%6%15%32%11%
1859
September1st to 15thNight
42%8%10%26%11%1
1800
16th to endNight
38%410%35%10%
1956
October1st to 15thNight
47%5%10%24%11%
2160
16th to endNight
56%5%13%18%5%
2407
November1st to 15thNight
52%5%14%17%9%
2527
16th to endNight
61%5%11%16%4
2730
December1st to 15thNight
64%6%12%12%4
2730
16th to endNight
65%49%13%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
28%12%30%23%41
90
16th to endDay
30%6%39%18%31
79
February1st to 15thDay
34%17%35%11%1
90
16th to endDay
31%17%23%20%5%
186
March1st to 15thDay
24%12%34%22%6%
270
16th to endDay
22%15%29%21%9%3
288
April1st to 15thDay
27%20%27%17%7%
270
16th to endDay
22%14%29%18%11%2
270
May1st to 15thDay
29%9%29%17%10%3
288
16th to endDay
22%12%31%20%11%2
331
June1st to 15thDay
25%8%30%23%10%1
315
16th to endDay
21%8%28%25%13%2
315
July1st to 15thDay
14%5%29%30%15%4
305
16th to endDay
11%424%34%18%5%
326
August1st to 15thDay
12%7%20%33%20%6%
313
16th to endDay
11%6%22%30%18%10%
332
September1st to 15thDay
17%6%23%20%20%12%
315
16th to endDay
17%7%19%23%21%10%
314
October1st to 15thDay
25%7%26%24%13%2
315
16th to endDay
30%13%24%23%7%
310
November1st to 15thDay
22%10%28%26%10%1
221
16th to endDay
31%18%27%20%2
90
December1st to 15thDay
20%15%37%22%4
90
16th to endDay
37%22%28%11%
96
January1st to 15thNight
28%12%31%21%5%
780
16th to endNight
22%9%34%26%6%
788
February1st to 15thNight
20%12%35%25%5%
704
16th to endNight
24%12%31%25%5%
631
March1st to 15thNight
25%12%34%23%3
720
16th to endNight
20%13%29%26%9%
768
April1st to 15thNight
28%10%31%24%4
718
16th to endNight
24%12%28%24%8%
639
May1st to 15thNight
26%6%25%29%9%1
360
16th to endNight
20%5%32%29%10%
375
June1st to 15thNight
20%429%34%10%
360
16th to endNight
18%424%36%13%1
360
July1st to 15thNight
9%226%44%17%
340
16th to endNight
9%123%43%19%1
376
August1st to 15thNight
15%319%36%23%1
431
16th to endNight
11%420%38%22%2
713
September1st to 15thNight
18%423%32%20%1
720
16th to endNight
19%5%21%26%23%2
717
October1st to 15thNight
23%8%27%26%13%1
720
16th to endNight
29%11%26%25%7%
768
November1st to 15thNight
26%8%29%23%11%
760
16th to endNight
29%15%26%21%7%
780
December1st to 15thNight
30%13%31%21%3
780
16th to endNight
32%9%32%19%41
832
Page generated at 2018-01-21 12:19:27. Version ac04

Copyright 2018 A. Danko


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