DVHS Espace Academy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the DVHS Espace Academy clear sky chart from 2005-11-06 to 2024-01-13.

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
62%
23606
30%
74756
24%
23558
70%
23558
43%
38326

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
54%
757
17%
2589
17%
756
58%
756
25%
1580
January11th to 20thNight
58%
728
21%
2366
19%
728
64%
728
28%
1416
January21st to endNight
58%
792
25%
2574
24%
792
63%
792
30%
1506
February1st to 10thNight
57%
720
27%
2340
25%
720
65%
720
31%
1354
February11th to 20thNight
54%
700
27%
2179
22%
700
63%
700
34%
1217
February21st to endNight
51%
592
28%
1776
22%
592
61%
592
36%
999
March1st to 10thNight
48%
720
19%
2044
14%
720
55%
720
29%
1294
March11th to 20thNight
51%
720
26%
1980
20%
720
57%
720
31%
1250
March21st to endNight
47%
792
23%
2129
12%
792
56%
792
36%
1276
April1st to 10thNight
49%
720
26%
1800
12%
720
57%
720
38%
1114
April11th to 20thNight
44%
711
32%
1779
11%
711
54%
711
45%
1006
April21st to endNight
53%
720
31%
1800
11%
720
62%
720
57%
935
May1st to 10thNight
57%
663
31%
1743
15%
663
64%
663
56%
877
May11th to 20thNight
65%
431
36%
1493
27%
431
75%
431
59%
596
May21st to endNight
58%
388
32%
1552
25%
388
74%
388
57%
551
June1st to 10thNight
60%
360
29%
1440
24%
360
76%
360
50%
563
June11th to 20thNight
65%
360
38%
1440
35%
360
80%
360
68%
451
June21st to endNight
68%
360
39%
1440
38%
360
82%
360
70%
451
July1st to 10thNight
75%
350
39%
1400
38%
350
90%
350
82%
403
July11th to 20thNight
79%
445
39%
1489
33%
445
87%
445
79%
520
July21st to endNight
76%
591
41%
1674
27%
558
86%
558
78%
647
August1st to 10thNight
72%
537
40%
1602
25%
534
81%
534
74%
641
August11th to 20thNight
76%
658
42%
1726
23%
658
83%
658
84%
727
August21st to endNight
81%
792
44%
1980
27%
792
84%
792
85%
863
September1st to 10thNight
78%
720
46%
1800
27%
720
85%
720
85%
784
September11th to 20thNight
73%
720
46%
1800
29%
720
81%
720
72%
854
September21st to endNight
76%
720
44%
2034
38%
720
84%
720
72%
852
October1st to 10thNight
72%
720
35%
2160
30%
720
83%
720
61%
949
October11th to 20thNight
73%
720
39%
2160
38%
720
80%
720
57%
989
October21st to endNight
72%
792
40%
2376
39%
792
79%
792
56%
1111
November1st to 10thNight
70%
740
33%
2294
30%
740
77%
740
45%
1153
November11th to 20thNight
67%
760
28%
2470
28%
760
72%
760
39%
1299
November21st to endNight
65%
760
29%
2607
29%
760
70%
760
38%
1334
December1st to 10thNight
57%
760
22%
2660
20%
760
63%
760
27%
1547
December11th to 20thNight
53%
760
18%
3237
20%
759
58%
759
17%
2215
December21st to endNight
46%
827
13%
4823
17%
817
55%
817
13%
3002

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%313323346%65%
74704
Night
7%313323347%62%
75029
TransparencyDay
21%48%20%26%21%
74420
Night
23%5%9%20%23%20%
74834
SeeingDay
7%10%25%32%21%6%
14187
Night
8%5%20%39%24%4
23623

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
19%9%47%5%2445%7%34%
1571
11th to 20thDay
11%6%36%434447%48%
1639
21st to endDay
13%7%35%5%345%5%7%41%
1782
February1st to 10thDay
12%5%37%5%24446%47%
1620
11th to 20thDay
12%435%425%45%8%49%
1668
21st to endDay
13%4244245%47%51%
1480
March1st to 10thDay
11%6%26%6%45%5%6%8%41%
1912
11th to 20thDay
11%6%26%6%345%6%8%42%
1980
21st to endDay
10%424435%45%7%51%
2227
April1st to 10thDay
11%6%245%2445%8%48%
2160
11th to 20thDay
7%41332345%6%62%
2129
21st to endDay
431322335%8%66%
2160
May1st to 10thDay
321232335%7%69%
2214
11th to 20thDay
321331225%7%72%
2395
21st to endDay
3212213247%73%
2723
June1st to 10thDay
2212223348%70%
2520
11th to 20thDay
11112345%83%
2520
21st to endDay
111111122386%
2520
July1st to 10thDay
11113488%
2520
11th to 20thDay
11111122487%
2416
21st to endDay
11112236%84%
2546
August1st to 10thDay
11111222484%
2328
11th to 20thDay
11112225%85%
2173
21st to endDay
111112488%
2376
September1st to 10thDay
1121112488%
2160
11th to 20thDay
1112212346%78%
2160
21st to endDay
221121222480%
1922
October1st to 10thDay
1212323326%75%
1800
11th to 20thDay
4312223446%71%
1800
21st to endDay
5%313313347%67%
1980
November1st to 10thDay
6%42442335%8%59%
1783
11th to 20thDay
8%6%35%5%3445%7%50%
1710
21st to endDay
10%5%2442335%7%55%
1568
December1st to 10thDay
11%7%35%5%4346%8%44%
1520
11th to 20thDay
22%10%47%6%33445%30%
1928
21st to endDay
14%9%5%7%6%345%6%8%33%
2794
January1st to 10thNight
14%5%35%4345%6%8%42%
2589
11th to 20thNight
10%5%25%5%3446%8%47%
2366
21st to endNight
13%4244345%6%8%48%
2574
February1st to 10thNight
14%424424346%52%
2340
11th to 20thNight
11%3234345%5%8%53%
2177
21st to endNight
12%424324346%56%
1776
March1st to 10thNight
12%5%346%345%5%6%47%
2044
11th to 20thNight
12%6%235%345%48%48%
1980
21st to endNight
11%423323346%57%
2129
April1st to 10thNight
8%434435%45%9%54%
1800
11th to 20thNight
7%313324346%64%
1779
21st to endNight
421222335%8%69%
1800
May1st to 10thNight
3212323247%71%
1743
11th to 20thNight
2112213349%73%
1493
21st to endNight
211212247%77%
1552
June1st to 10thNight
322323348%72%
1440
11th to 20thNight
1111133485%
1440
21st to endNight
11111122485%
1440
July1st to 10thNight
11112489%
1440
11th to 20thNight
111111122387%
1538
21st to endNight
111112349%77%
1773
August1st to 10thNight
211111227%80%
1611
11th to 20thNight
1111247%82%
1726
21st to endNight
111112125%86%
1980
September1st to 10thNight
11111226%86%
1800
11th to 20thNight
1211112238%78%
1800
21st to endNight
1111212235%82%
2034
October1st to 10thNight
3212212245%76%
2160
11th to 20thNight
321131345%7%70%
2160
21st to endNight
5%21231235%7%69%
2376
November1st to 10thNight
6%31332435%9%62%
2294
11th to 20thNight
8%42442345%8%57%
2470
21st to endNight
8%313424447%59%
2607
December1st to 10thNight
11%6%3443345%6%49%
2660
11th to 20thNight
19%8%36%4445%6%8%33%
3276
21st to endNight
15%7%37%7%35%6%5%6%36%
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
49%6%13%18%11%3
1571
11th to 20thDay
38%5%12%18%20%8%
1639
21st to endDay
41%6%11%16%21%5%
1782
February1st to 10thDay
38%49%22%19%7%
1620
11th to 20thDay
34%6%10%20%23%6%
1677
21st to endDay
33%6%9%23%21%7%
1480
March1st to 10thDay
41%7%11%21%17%4
1912
11th to 20thDay
39%7%9%22%16%6%
1980
21st to endDay
32%7%15%21%20%5%
2227
April1st to 10thDay
34%6%12%20%20%6%
2160
11th to 20thDay
24%414%26%24%8%
2132
21st to endDay
17%413%29%30%7%
2160
May1st to 10thDay
16%5%8%28%33%10%
2214
11th to 20thDay
15%47%29%33%12%
2398
21st to endDay
14%413%34%27%8%
2724
June1st to 10thDay
15%410%26%31%14%
2520
11th to 20thDay
5%38%22%35%27%
2520
21st to endDay
7%1312%33%44%
2520
July1st to 10thDay
4138%25%59%
2451
11th to 20thDay
5%2413%23%54%
2342
21st to endDay
4228%28%56%
2405
August1st to 10thDay
7%2311%32%46%
2312
11th to 20thDay
42112%34%47%
2173
21st to endDay
31212%36%45%
2376
September1st to 10thDay
5%228%31%52%
2160
11th to 20thDay
8%45%22%39%23%
2160
21st to endDay
9%3420%36%28%
1922
October1st to 10thDay
14%36%18%30%29%
1800
11th to 20thDay
15%49%22%24%26%
1800
21st to endDay
20%39%21%27%20%
1980
November1st to 10thDay
25%6%9%27%22%11%
1783
11th to 20thDay
33%412%25%21%5%
1710
21st to endDay
30%411%21%26%7%
1568
December1st to 10thDay
37%7%12%21%16%7%
1520
11th to 20thDay
57%5%8%14%13%3
1928
21st to endDay
47%5%16%18%11%2
2794
January1st to 10thNight
39%6%15%24%12%5%
2589
11th to 20thNight
35%7%13%18%15%11%
2366
21st to endNight
34%6%14%17%21%9%
2574
February1st to 10thNight
34%47%21%23%10%
2340
11th to 20thNight
30%5%10%22%23%9%
2179
21st to endNight
30%5%11%28%21%6%
1776
March1st to 10thNight
37%6%13%20%17%6%
2044
11th to 20thNight
35%7%7%23%21%7%
1980
21st to endNight
29%7%12%23%21%8%
2129
April1st to 10thNight
30%6%14%21%21%9%
1800
11th to 20thNight
23%5%12%28%21%12%
1779
21st to endNight
15%5%12%30%30%8%
1800
May1st to 10thNight
15%5%9%24%33%13%
1743
11th to 20thNight
11%5%10%28%33%14%
1493
21st to endNight
10%414%35%28%10%
1552
June1st to 10thNight
14%411%23%31%16%
1440
11th to 20thNight
6%38%18%34%32%
1440
21st to endNight
6%3213%30%46%
1440
July1st to 10thNight
4128%23%62%
1400
11th to 20thNight
5%239%20%61%
1489
21st to endNight
6%237%23%59%
1674
August1st to 10thNight
8%2212%27%50%
1602
11th to 20thNight
42210%29%52%
1726
21st to endNight
4229%32%50%
1980
September1st to 10thNight
4238%26%57%
1800
11th to 20thNight
8%5%420%34%30%
1800
21st to endNight
8%35%19%33%33%
2034
October1st to 10thNight
12%48%18%27%31%
2160
11th to 20thNight
14%5%8%19%24%30%
2160
21st to endNight
15%46%21%29%25%
2376
November1st to 10thNight
21%5%10%27%21%16%
2294
11th to 20thNight
26%5%11%26%24%8%
2470
21st to endNight
26%5%9%22%27%11%
2607
December1st to 10thNight
34%7%10%20%17%11%
2660
11th to 20thNight
50%5%11%14%16%3
3276
21st to endNight
46%6%15%17%12%3
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
25%10%25%22%16%3
232
11th to 20thDay
15%9%21%27%22%6%
347
21st to endDay
14%8%20%26%24%8%
374
February1st to 10thDay
16%13%20%21%23%8%
340
11th to 20thDay
14%17%25%20%19%5%
377
21st to endDay
12%18%24%25%19%3
346
March1st to 10thDay
15%14%29%26%12%4
420
11th to 20thDay
17%14%26%23%15%6%
420
21st to endDay
12%17%30%26%12%2
462
April1st to 10thDay
12%18%29%21%14%5%
420
11th to 20thDay
9%19%33%22%13%4
412
21st to endDay
221%29%28%15%5%
420
May1st to 10thDay
5%14%35%29%14%3
423
11th to 20thDay
6%13%35%26%18%2
448
21st to endDay
312%29%35%17%4
485
June1st to 10thDay
313%30%31%19%3
450
11th to 20thDay
112%31%39%16%2
450
21st to endDay
16%29%42%20%3
450
July1st to 10thDay
227%50%19%2
446
11th to 20thDay
221%48%26%3
444
21st to endDay
1124%45%24%5%
487
August1st to 10thDay
1426%47%19%3
447
11th to 20thDay
325%41%22%8%
437
21st to endDay
1219%46%27%6%
495
September1st to 10thDay
419%42%28%7%
450
11th to 20thDay
28%24%39%21%7%
450
21st to endDay
16%22%37%25%9%
450
October1st to 10thDay
38%24%29%25%12%
450
11th to 20thDay
5%8%18%27%30%13%
450
21st to endDay
7%8%19%28%25%14%
495
November1st to 10thDay
7%9%22%21%30%12%
379
11th to 20thDay
7%7%15%33%25%13%
270
21st to endDay
10%5%22%31%28%4
203
December1st to 10thDay
17%11%19%24%21%8%
180
11th to 20thDay
19%12%17%20%25%7%
180
21st to endDay
18%12%23%25%18%4
198
January1st to 10thNight
16%5%16%33%23%6%
760
11th to 20thNight
11%6%16%36%25%6%
728
21st to endNight
15%5%15%34%26%5%
792
February1st to 10thNight
15%7%15%35%24%4
720
11th to 20thNight
10%9%20%33%23%5%
704
21st to endNight
11%11%22%35%18%2
592
March1st to 10thNight
15%10%20%33%20%3
720
11th to 20thNight
13%10%22%33%20%3
720
21st to endNight
11%8%28%34%17%2
792
April1st to 10thNight
10%8%26%38%17%2
720
11th to 20thNight
7%11%33%28%17%3
711
21st to endNight
5%8%32%34%18%3
720
May1st to 10thNight
46%31%40%16%3
663
11th to 20thNight
3425%46%21%1
431
21st to endNight
36%31%44%16%
389
June1st to 10thNight
2431%50%13%
360
11th to 20thNight
15%27%53%13%1
360
21st to endNight
1228%52%18%
360
July1st to 10thNight
123%57%19%
350
11th to 20thNight
1117%55%25%2
445
21st to endNight
2117%47%31%1
591
August1st to 10thNight
2122%44%28%3
537
11th to 20thNight
121%49%28%1
658
21st to endNight
1115%51%30%2
792
September1st to 10thNight
1218%45%31%4
720
11th to 20thNight
1321%45%27%3
720
21st to endNight
1416%40%32%6%
720
October1st to 10thNight
3419%39%29%6%
720
11th to 20thNight
4416%38%34%4
720
21st to endNight
5%415%36%31%10%
792
November1st to 10thNight
6%415%36%31%8%
740
11th to 20thNight
8%314%40%30%5%
760
21st to endNight
8%416%35%30%6%
760
December1st to 10thNight
13%6%16%36%23%6%
760
11th to 20thNight
19%6%13%34%23%4
760
21st to endNight
17%8%20%34%20%2
836
Page generated at 2024-01-09 22:25:04. Version ac07

Copyright 2024 Attilla Danko


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