Schumann Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Schumann Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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
38%
23667
20%
74611
12%
23620
48%
23620
24%
46969

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
22%
757
24%
2583
8%
757
41%
757
20%
1541
January11th to 20thNight
26%
725
21%
2354
8%
725
42%
725
18%
1538
January21st to endNight
23%
792
25%
2574
10%
792
41%
792
23%
1550
February1st to 10thNight
21%
720
18%
2340
9%
720
34%
720
22%
1484
February11th to 20thNight
15%
700
20%
2150
6%
700
33%
700
19%
1391
February21st to endNight
21%
592
27%
1776
10%
592
40%
592
23%
1122
March1st to 10thNight
26%
720
23%
2052
9%
720
41%
720
28%
1269
March11th to 20thNight
25%
720
19%
1980
9%
720
36%
720
22%
1338
March21st to endNight
23%
792
20%
2115
7%
792
34%
792
23%
1437
April1st to 10thNight
22%
720
20%
1800
4%
720
33%
720
26%
1220
April11th to 20thNight
32%
711
24%
1775
7%
711
41%
711
35%
1131
April21st to endNight
34%
720
20%
1800
8%
720
39%
720
30%
1198
May1st to 10thNight
31%
716
15%
1796
6%
716
36%
716
25%
1255
May11th to 20thNight
39%
422
17%
1484
11%
422
45%
422
21%
956
May21st to endNight
54%
388
17%
1551
17%
388
58%
388
21%
948
June1st to 10thNight
56%
360
16%
1440
19%
360
60%
360
22%
873
June11th to 20thNight
55%
360
15%
1440
15%
360
60%
360
21%
870
June21st to endNight
57%
360
17%
1440
16%
360
64%
360
23%
854
July1st to 10thNight
60%
350
16%
1400
18%
350
62%
350
21%
845
July11th to 20thNight
74%
435
17%
1479
18%
435
75%
435
31%
864
July21st to endNight
64%
591
17%
1672
14%
558
67%
558
27%
1072
August1st to 10thNight
61%
537
12%
1600
9%
534
63%
534
23%
1084
August11th to 20thNight
58%
688
16%
1752
10%
688
59%
688
27%
1213
August21st to endNight
60%
792
16%
1980
8%
792
61%
792
29%
1367
September1st to 10thNight
59%
720
22%
1800
14%
720
62%
720
32%
1212
September11th to 20thNight
58%
720
27%
1800
18%
720
62%
720
33%
1190
September21st to endNight
41%
720
17%
2030
12%
720
47%
720
21%
1431
October1st to 10thNight
47%
720
21%
2160
17%
720
54%
720
26%
1380
October11th to 20thNight
42%
720
26%
2160
19%
720
54%
720
28%
1318
October21st to endNight
36%
792
27%
2376
18%
792
49%
792
28%
1430
November1st to 10thNight
38%
740
23%
2325
14%
740
50%
740
27%
1402
November11th to 20thNight
32%
760
23%
2470
14%
760
45%
760
24%
1498
November21st to endNight
37%
760
26%
2555
16%
760
52%
760
26%
1461
December1st to 10thNight
25%
760
20%
2660
9%
760
40%
760
18%
1701
December11th to 20thNight
26%
760
22%
3180
11%
759
43%
759
19%
1904
December21st to endNight
31%
827
16%
4762
14%
817
45%
817
14%
2622

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
14%5%25%5%345%6%8%44%
74669
Night
14%6%25%5%3445%7%44%
75032
TransparencyDay
36%8%13%23%16%3
74380
Night
39%7%12%23%16%3
74841
SeeingDay
17%10%29%27%14%4
14038
Night
17%11%28%29%13%2
23683

By Month

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 10thDay
15%5%25%5%345%5%6%45%
1578
11th to 20thDay
15%7%35%5%3445%6%44%
1629
21st to endDay
16%7%36%42335%7%46%
1782
February1st to 10thDay
13%9%25%5%45%5%5%7%40%
1620
11th to 20thDay
20%5%33424346%46%
1695
21st to endDay
16%9%346%45%5%5%5%37%
1480
March1st to 10thDay
13%6%245%33445%51%
1905
11th to 20thDay
17%5%3442445%7%45%
1980
21st to endDay
16%5%345%345%5%6%43%
2240
April1st to 10thDay
12%5%2443345%7%51%
2160
11th to 20thDay
10%5%245%45%447%50%
2134
21st to endDay
15%6%245%345%5%8%44%
2160
May1st to 10thDay
15%5%25%5%345%5%9%42%
2178
11th to 20thDay
17%435%6%35%5%5%8%40%
2406
21st to endDay
14%5%244245%6%8%45%
2725
June1st to 10thDay
12%4145%35%6%8%10%43%
2520
11th to 20thDay
11%4245%35%6%8%10%42%
2520
21st to endDay
8%325%5%36%6%7%11%44%
2520
July1st to 10thDay
9%435%6%45%6%7%10%42%
2520
11th to 20thDay
6%425%6%46%7%8%11%41%
2428
21st to endDay
7%325%7%46%7%8%12%38%
2547
August1st to 10thDay
10%6%25%6%45%7%8%10%37%
2327
11th to 20thDay
13%426%6%46%6%7%10%37%
2131
21st to endDay
12%5%25%5%35%6%7%11%40%
2376
September1st to 10thDay
14%5%25%4345%5%8%44%
2160
11th to 20thDay
14%6%35%43446%7%44%
2160
21st to endDay
20%7%245%3445%7%39%
1925
October1st to 10thDay
16%5%25%5%3335%7%45%
1800
11th to 20thDay
17%5%24323445%51%
1800
21st to endDay
13%5%244335%5%6%49%
1980
November1st to 10thDay
15%5%24323346%52%
1751
11th to 20thDay
14%6%25%325%336%51%
1710
21st to endDay
16%42343345%6%51%
1620
December1st to 10thDay
16%7%3442446%7%44%
1520
11th to 20thDay
17%5%25%323335%52%
1910
21st to endDay
17%6%35%5%2345%6%45%
2772
January1st to 10thNight
15%6%25%5%2435%6%47%
2583
11th to 20thNight
16%6%35%5%45%45%7%40%
2354
21st to endNight
17%6%2342435%6%47%
2574
February1st to 10thNight
16%8%35%42445%6%42%
2340
11th to 20thNight
20%6%35%5%2445%5%43%
2148
21st to endNight
19%7%2432335%5%47%
1776
March1st to 10thNight
14%5%25%42435%6%50%
2052
11th to 20thNight
19%6%35%5%25%5%6%6%40%
1980
21st to endNight
16%7%35%5%35%45%6%42%
2115
April1st to 10thNight
14%7%35%5%345%6%7%42%
1800
11th to 20thNight
12%5%25%42445%8%50%
1775
21st to endNight
17%5%2443445%7%45%
1800
May1st to 10thNight
15%6%35%6%35%5%6%8%39%
1796
11th to 20thNight
15%7%36%5%35%45%8%39%
1483
21st to endNight
15%415%5%35%5%5%8%43%
1550
June1st to 10thNight
12%425%5%37%5%7%8%41%
1440
11th to 20thNight
11%4245%46%5%8%10%41%
1440
21st to endNight
9%425%7%45%6%8%10%41%
1440
July1st to 10thNight
9%436%6%5%5%5%7%10%41%
1440
11th to 20thNight
5%425%5%45%7%7%12%45%
1527
21st to endNight
8%425%6%46%7%7%11%40%
1771
August1st to 10thNight
8%437%8%5%5%8%8%10%36%
1611
11th to 20thNight
9%7%37%6%345%7%10%38%
1752
21st to endNight
10%6%26%6%35%6%7%9%40%
1980
September1st to 10thNight
14%5%244245%6%8%46%
1800
11th to 20thNight
12%5%35%5%345%5%7%47%
1800
21st to endNight
22%7%35%425%45%7%37%
2030
October1st to 10thNight
16%5%25%5%3445%8%44%
2160
11th to 20thNight
17%5%24434346%49%
2160
21st to endNight
16%5%24423447%49%
2376
November1st to 10thNight
15%6%245%24346%49%
2325
11th to 20thNight
16%6%245%24446%49%
2470
21st to endNight
12%5%2443445%7%51%
2555
December1st to 10thNight
17%7%36%435%45%5%41%
2660
11th to 20thNight
17%6%24424446%45%
3285
21st to endNight
14%7%35%43445%8%43%
4884

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
39%6%11%26%15%4
1579
11th to 20thDay
43%411%23%15%3
1629
21st to endDay
39%411%24%18%4
1782
February1st to 10thDay
43%6%11%25%13%3
1620
11th to 20thDay
40%410%22%20%4
1704
21st to endDay
46%7%11%17%15%4
1480
March1st to 10thDay
36%6%11%23%21%3
1905
11th to 20thDay
38%6%12%21%17%5%
1980
21st to endDay
41%8%11%19%18%3
2240
April1st to 10thDay
33%6%13%22%20%6%
2160
11th to 20thDay
33%7%12%23%20%6%
2134
21st to endDay
37%8%11%23%16%5%
2160
May1st to 10thDay
37%9%15%22%15%3
2178
11th to 20thDay
40%10%13%24%11%2
2410
21st to endDay
34%10%15%27%13%1
2725
June1st to 10thDay
32%10%17%27%12%1
2520
11th to 20thDay
32%11%18%23%14%2
2520
21st to endDay
32%11%17%23%16%1
2520
July1st to 10thDay
32%13%16%21%15%2
2450
11th to 20thDay
29%13%20%27%9%1
2354
21st to endDay
33%12%19%20%14%1
2405
August1st to 10thDay
35%12%18%25%9%1
2314
11th to 20thDay
40%10%15%23%12%1
2131
21st to endDay
34%10%15%24%13%3
2376
September1st to 10thDay
36%9%17%18%16%4
2160
11th to 20thDay
37%6%12%23%19%2
2160
21st to endDay
44%7%9%23%15%3
1925
October1st to 10thDay
38%7%10%24%18%3
1800
11th to 20thDay
35%6%10%24%21%4
1800
21st to endDay
35%6%8%24%22%6%
1980
November1st to 10thDay
34%5%10%28%20%4
1751
11th to 20thDay
36%5%12%19%22%6%
1710
21st to endDay
35%411%26%20%4
1620
December1st to 10thDay
41%5%13%24%14%3
1520
11th to 20thDay
38%5%8%27%16%6%
1906
21st to endDay
40%6%11%27%14%1
2772
January1st to 10thNight
40%310%23%19%5%
2583
11th to 20thNight
44%6%12%20%15%4
2354
21st to endNight
39%410%25%18%4
2574
February1st to 10thNight
43%411%23%15%3
2340
11th to 20thNight
44%48%21%17%6%
2150
21st to endNight
40%5%9%22%19%6%
1776
March1st to 10thNight
37%5%10%26%20%3
2052
11th to 20thNight
43%6%10%20%17%4
1980
21st to endNight
43%6%10%21%16%5%
2115
April1st to 10thNight
40%7%11%18%21%4
1800
11th to 20thNight
33%6%11%23%22%5%
1775
21st to endNight
38%7%13%22%16%4
1800
May1st to 10thNight
40%9%13%21%14%3
1796
11th to 20thNight
42%8%14%21%14%1
1484
21st to endNight
38%10%15%24%12%1
1551
June1st to 10thNight
37%10%15%22%15%1
1440
11th to 20thNight
36%12%16%21%14%2
1440
21st to endNight
37%9%14%23%14%3
1440
July1st to 10thNight
38%10%16%22%13%3
1400
11th to 20thNight
28%12%21%29%9%1
1479
21st to endNight
34%12%17%24%12%
1672
August1st to 10thNight
39%13%19%21%9%
1600
11th to 20thNight
39%11%17%19%13%1
1752
21st to endNight
38%11%15%22%13%2
1980
September1st to 10thNight
35%10%16%20%16%4
1800
11th to 20thNight
36%7%9%26%20%2
1800
21st to endNight
46%8%10%16%17%2
2030
October1st to 10thNight
39%7%10%23%18%3
2160
11th to 20thNight
37%5%9%23%22%4
2160
21st to endNight
35%5%9%25%21%4
2376
November1st to 10thNight
38%411%24%18%4
2325
11th to 20thNight
38%5%10%21%19%8%
2470
21st to endNight
34%5%9%26%21%4
2555
December1st to 10thNight
45%5%10%22%15%3
2660
11th to 20thNight
40%6%10%22%19%4
3288
21st to endNight
38%7%14%26%14%2
4884

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
22%18%38%17%4
209
11th to 20thDay
19%26%39%13%4
243
21st to endDay
19%21%38%20%2
264
February1st to 10thDay
19%21%43%12%4
240
11th to 20thDay
27%19%39%13%1
363
21st to endDay
24%18%40%14%3
346
March1st to 10thDay
17%21%40%16%4
420
11th to 20thDay
21%19%37%17%5%1
420
21st to endDay
19%16%43%16%41
462
April1st to 10thDay
16%22%38%18%5%1
420
11th to 20thDay
11%15%40%24%7%3
412
21st to endDay
18%14%38%24%5%1
420
May1st to 10thDay
17%13%39%22%8%1
423
11th to 20thDay
21%8%32%27%10%2
447
21st to endDay
22%325%27%18%4
485
June1st to 10thDay
15%5%23%32%21%4
450
11th to 20thDay
12%5%22%36%20%5%
450
21st to endDay
10%424%38%21%4
450
July1st to 10thDay
10%315%36%29%6%
445
11th to 20thDay
6%113%43%30%8%
444
21st to endDay
11%219%37%24%7%
488
August1st to 10thDay
11%417%38%22%8%
446
11th to 20thDay
14%212%36%28%8%
439
21st to endDay
11%318%31%26%11%
495
September1st to 10thDay
15%419%31%20%11%
450
11th to 20thDay
14%420%35%20%7%
450
21st to endDay
28%6%22%27%13%4
450
October1st to 10thDay
21%424%28%17%6%
450
11th to 20thDay
17%10%28%28%15%3
450
21st to endDay
14%11%35%27%10%3
495
November1st to 10thDay
19%11%29%24%12%5%
404
11th to 20thDay
16%17%33%24%9%1
370
21st to endDay
18%16%29%25%11%1
280
December1st to 10thDay
23%14%38%19%5%1
180
11th to 20thDay
21%15%33%24%6%
180
21st to endDay
23%15%31%22%9%
198
January1st to 10thNight
19%19%35%23%4
760
11th to 20thNight
21%15%33%24%6%
725
21st to endNight
20%17%37%24%2
792
February1st to 10thNight
20%13%41%23%3
720
11th to 20thNight
23%22%36%17%2
703
21st to endNight
20%18%36%23%2
592
March1st to 10thNight
17%16%37%24%5%
720
11th to 20thNight
22%15%33%23%6%1
720
21st to endNight
19%14%40%23%5%
792
April1st to 10thNight
18%16%40%20%5%
720
11th to 20thNight
14%12%38%26%9%
711
21st to endNight
19%9%34%30%8%1
720
May1st to 10thNight
18%10%34%30%7%1
716
11th to 20thNight
17%7%28%35%12%1
422
21st to endNight
17%416%37%24%2
389
June1st to 10thNight
14%319%43%20%2
360
11th to 20thNight
11%423%38%20%5%
360
21st to endNight
9%321%43%21%3
360
July1st to 10thNight
12%213%44%26%3
350
11th to 20thNight
5%111%44%33%6%
435
21st to endNight
7%314%44%27%4
591
August1st to 10thNight
10%213%43%27%5%
537
11th to 20thNight
12%413%37%31%3
688
21st to endNight
12%315%33%30%7%
792
September1st to 10thNight
17%313%34%28%6%
720
11th to 20thNight
14%315%34%29%6%
720
21st to endNight
23%6%21%29%19%3
720
October1st to 10thNight
18%6%22%29%21%5%
720
11th to 20thNight
19%10%24%29%15%2
720
21st to endNight
19%12%27%27%14%2
792
November1st to 10thNight
18%9%27%27%15%3
740
11th to 20thNight
18%15%29%27%11%1
760
21st to endNight
14%18%27%31%9%2
760
December1st to 10thNight
20%14%33%21%10%2
760
11th to 20thNight
19%12%38%25%6%
760
21st to endNight
19%14%29%31%6%
836
Page generated at 2024-01-08 22:31:23. Version ac07

Copyright 2024 Attilla Danko


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