Hahnenberg Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hahnenberg Observatory clear sky chart from 2005-11-05 to 2017-09-24.

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
35%
15977
11%
47032
8%
15935
38%
15935
15%
35997

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
12%
900
2%
2506
1%
895
13%
895
4%
2315
January16th to endNight
14%
960
3%
2688
1%
960
15%
960
4%
2474
February1st to 15thNight
18%
767
4%
2292
2%
767
20%
767
6%
2009
February16th to endNight
24%
631
8%
1893
4%
631
27%
631
9%
1599
March1st to 15thNight
34%
720
13%
2142
9%
720
37%
720
17%
1590
March16th to endNight
40%
715
17%
2059
13%
715
44%
715
21%
1470
April1st to 15thNight
35%
539
13%
1797
10%
539
40%
539
17%
1264
April16th to endNight
42%
540
19%
1623
13%
540
48%
540
23%
1112
May1st to 15thNight
45%
540
13%
1609
10%
540
48%
540
20%
1137
May16th to endNight
54%
562
15%
1498
10%
561
58%
561
32%
973
June1st to 15thNight
52%
468
12%
1368
9%
468
55%
468
25%
910
June16th to endNight
60%
476
13%
1376
9%
476
61%
476
30%
874
July1st to 15thNight
66%
510
15%
1360
10%
510
68%
510
39%
816
July16th to endNight
64%
564
16%
1417
12%
531
65%
531
37%
868
August1st to 15thNight
68%
539
19%
1542
16%
536
70%
536
36%
906
August16th to endNight
60%
573
17%
1796
15%
573
62%
573
29%
1098
September1st to 15thNight
57%
597
16%
1857
14%
597
60%
597
27%
1187
September16th to endNight
54%
693
18%
1914
14%
693
55%
693
27%
1286
October1st to 15thNight
38%
660
15%
1877
11%
660
42%
660
19%
1376
October16th to endNight
25%
704
8%
2288
6%
704
28%
704
10%
1854
November1st to 15thNight
28%
700
13%
2276
11%
700
32%
700
13%
1742
November16th to endNight
19%
759
6%
2403
4%
759
21%
759
6%
2094
December1st to 15thNight
9%
900
1%
2700
1%
900
9%
900
3%
2517
December16th to endNight
10%
960
3%
2751
1%
960
13%
960
4%
2526

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%9%47%6%34446%33%
47885
Night
15%11%5%9%7%34445%28%
47200
Cloud CoverDay
14%9%47%6%34446%33%
47894
Night
15%11%5%9%7%34345%28%
47205
TransparencyDay
51%5%11%20%9%
47571
Night
58%5%10%16%8%
47032
SeeingDay
16%423%29%20%5%
6049
Night
20%7%25%29%14%1
15981

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
16%18%11%16%11%5%42337%
1432
16th to endDay
13%15%12%17%14%5%5%3325%
1536
February1st to 15thDay
13%15%7%14%14%47%33410%
1569
16th to endDay
13%16%8%11%9%46%45%5%14%
1580
March1st to 15thDay
12%9%5%10%9%35%445%29%
1807
16th to endDay
15%8%5%8%5%345%5%6%32%
2175
April1st to 15thDay
19%12%35%32435%5%34%
2151
16th to endDay
16%9%36%43435%6%36%
2337
May1st to 15thDay
14%7%25%6%3445%5%39%
2340
16th to endDay
10%5%235%15%46%7%45%
2617
June1st to 15thDay
12%5%15%5%3446%7%42%
2585
16th to endDay
11%425%4345%5%8%44%
2574
July1st to 15thDay
9%42332445%8%51%
2520
16th to endDay
7%3244235%6%9%50%
2655
August1st to 15thDay
7%315%42446%9%49%
2407
16th to endDay
13%6%25%423347%46%
2405
September1st to 15thDay
14%5%345%33447%43%
2091
16th to endDay
15%4245%245%6%7%40%
1905
October1st to 15thDay
20%9%37%5%34346%30%
1752
16th to endDay
26%14%38%8%35%335%17%
1584
November1st to 15thDay
17%16%47%6%3435%6%25%
1582
16th to endDay
19%24%7%12%7%1442312%
1551
December1st to 15thDay
19%20%14%15%10%232116%
1260
16th to endDay
21%23%10%11%9%233238%
1470
January1st to 15thNight
18%17%8%14%12%5%432210%
2506
16th to endNight
13%17%9%15%14%5%6%3339%
2688
February1st to 15thNight
12%16%7%14%13%5%5%33314%
2290
16th to endNight
16%14%6%14%8%44445%16%
1893
March1st to 15thNight
12%10%49%7%35%445%32%
2129
16th to endNight
13%9%5%7%6%24445%34%
2059
April1st to 15thNight
21%9%36%5%33445%32%
1797
16th to endNight
16%8%35%434435%40%
1623
May1st to 15thNight
14%7%26%6%37%45%6%33%
1609
16th to endNight
10%6%25%4335%6%8%43%
1496
June1st to 15thNight
13%6%25%5%4445%6%41%
1368
16th to endNight
9%5%25%5%35%35%10%42%
1376
July1st to 15thNight
9%324324447%51%
1440
16th to endNight
8%32442346%7%51%
1513
August1st to 15thNight
6%41443446%8%50%
1551
16th to endNight
12%5%145%34346%48%
1796
September1st to 15thNight
12%6%15%424445%46%
1857
16th to endNight
15%5%25%43345%8%41%
1914
October1st to 15thNight
22%10%37%422346%32%
1877
16th to endNight
22%11%39%7%4444421%
2288
November1st to 15thNight
17%15%47%6%34346%26%
2276
16th to endNight
20%20%6%12%7%44335%12%
2403
December1st to 15thNight
17%21%11%15%9%433228%
2700
16th to endNight
18%22%11%13%7%343338%
2751

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
16%18%11%16%11%5%42237%
1432
16th to endDay
13%15%12%17%13%6%6%3225%
1536
February1st to 15thDay
13%14%8%14%13%5%6%33410%
1569
16th to endDay
12%16%8%11%10%45%45%5%14%
1580
March1st to 15thDay
12%9%411%8%45%44430%
1817
16th to endDay
15%7%48%6%345%5%6%32%
2174
April1st to 15thDay
19%12%35%32435%5%34%
2151
16th to endDay
16%10%36%434346%36%
2337
May1st to 15thDay
14%7%35%6%35%45%5%39%
2340
16th to endDay
10%5%24425%45%7%45%
2617
June1st to 15thDay
12%5%25%5%2445%7%42%
2585
16th to endDay
11%425%4345%5%8%44%
2574
July1st to 15thDay
9%41332446%8%51%
2520
16th to endDay
7%31342447%9%50%
2655
August1st to 15thDay
7%31442446%9%49%
2407
16th to endDay
12%6%245%23346%46%
2405
September1st to 15thDay
14%6%25%5%34447%43%
2091
16th to endDay
15%4244245%6%8%40%
1905
October1st to 15thDay
19%9%37%6%24446%30%
1752
16th to endDay
25%15%39%7%34435%16%
1584
November1st to 15thDay
17%15%5%8%6%2435%6%24%
1582
16th to endDay
19%22%7%12%7%2432412%
1551
December1st to 15thDay
19%20%14%17%10%131226%
1260
16th to endDay
21%23%9%11%10%232238%
1470
January1st to 15thNight
18%17%8%15%12%5%42229%
2506
16th to endNight
13%17%9%15%14%5%5%3338%
2688
February1st to 15thNight
12%16%8%13%13%45%33313%
2283
16th to endNight
16%13%7%13%8%44435%16%
1893
March1st to 15thNight
12%10%49%6%44445%33%
2142
16th to endNight
13%10%5%7%5%34445%34%
2059
April1st to 15thNight
21%9%36%424445%32%
1797
16th to endNight
16%8%35%434345%40%
1623
May1st to 15thNight
14%7%36%6%38%45%7%32%
1608
16th to endNight
10%5%25%4235%7%7%44%
1496
June1st to 15thNight
13%6%25%5%35%446%41%
1368
16th to endNight
9%5%25%5%25%36%8%43%
1376
July1st to 15thNight
9%41442445%7%51%
1440
16th to endNight
8%325%5%2345%8%51%
1513
August1st to 15thNight
6%42343447%7%50%
1551
16th to endNight
12%5%245%23346%48%
1796
September1st to 15thNight
12%5%25%434446%45%
1857
16th to endNight
15%5%25%5%2436%8%41%
1914
October1st to 15thNight
22%8%37%5%32345%32%
1877
16th to endNight
22%11%410%7%34445%21%
2288
November1st to 15thNight
17%14%47%6%34346%26%
2276
16th to endNight
20%19%6%11%8%4433412%
2403
December1st to 15thNight
18%21%11%15%10%442127%
2700
16th to endNight
18%22%10%13%7%343238%
2751

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
84%5%44
1433
16th to endDay
85%5%34
1536
February1st to 15thDay
78%5%6%8%1
1571
16th to endDay
71%6%8%9%3
1580
March1st to 15thDay
56%6%13%16%5%
1817
16th to endDay
51%6%13%22%5%1
2175
April1st to 15thDay
51%410%21%10%
2151
16th to endDay
48%5%11%16%15%2
2337
May1st to 15thDay
46%5%10%23%11%3
2340
16th to endDay
35%7%13%26%15%2
2621
June1st to 15thDay
38%5%13%27%13%1
2585
16th to endDay
37%7%16%24%13%1
2574
July1st to 15thDay
29%6%12%32%17%1
2371
16th to endDay
30%6%16%27%17%1
2488
August1st to 15thDay
30%6%18%31%12%
2392
16th to endDay
38%413%27%14%1
2405
September1st to 15thDay
40%6%13%27%11%
2091
16th to endDay
40%6%16%26%9%
1905
October1st to 15thDay
56%5%10%20%7%
1752
16th to endDay
70%5%11%9%2
1584
November1st to 15thDay
60%5%11%15%7%
1582
16th to endDay
77%49%6%1
1551
December1st to 15thDay
87%334
1260
16th to endDay
83%47%31
1470
January1st to 15thNight
82%45%5%
2506
16th to endNight
82%5%6%4
2688
February1st to 15thNight
77%47%8%2
2292
16th to endNight
70%5%9%10%3
1893
March1st to 15thNight
54%6%11%18%8%
2142
16th to endNight
50%5%11%21%9%1
2059
April1st to 15thNight
53%48%19%11%1
1797
16th to endNight
46%5%9%19%15%3
1623
May1st to 15thNight
49%6%10%19%11%3
1609
16th to endNight
37%6%13%25%14%2
1498
June1st to 15thNight
42%6%11%23%15%
1368
16th to endNight
38%5%15%23%14%1
1376
July1st to 15thNight
29%6%13%28%19%2
1360
16th to endNight
31%6%14%28%17%1
1417
August1st to 15thNight
30%6%17%31%13%
1542
16th to endNight
37%5%15%24%15%1
1796
September1st to 15thNight
39%7%12%23%16%
1857
16th to endNight
40%7%14%27%8%
1914
October1st to 15thNight
53%49%20%10%
1877
16th to endNight
65%6%11%12%3
2288
November1st to 15thNight
59%5%11%15%6%
2276
16th to endNight
76%5%9%6%1
2403
December1st to 15thNight
85%344
2700
16th to endNight
82%5%6%31
2751

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%12%28%31%6%
90
16th to endDay
30%6%22%31%8%1
96
February1st to 15thDay
22%8%43%18%6%
90
16th to endDay
19%7%44%17%11%
81
March1st to 15thDay
19%9%30%24%14%
107
16th to endDay
23%5%23%30%15%1
288
April1st to 15thDay
27%425%27%13%2
270
16th to endDay
21%5%28%24%15%4
270
May1st to 15thDay
17%427%29%16%3
297
16th to endDay
14%325%29%22%4
517
June1st to 15thDay
15%324%30%21%5%
495
16th to endDay
12%222%35%21%5%
495
July1st to 15thDay
10%218%32%28%7%
475
16th to endDay
8%21%34%27%6%
515
August1st to 15thDay
10%113%36%28%10%
380
16th to endDay
18%215%27%27%8%
332
September1st to 15thDay
13%319%22%25%14%
315
16th to endDay
13%416%32%27%6%
287
October1st to 15thDay
25%6%20%31%14%2
233
16th to endDay
27%6%35%26%41
96
November1st to 15thDay
15%7%27%26%20%2
90
16th to endDay
27%21%23%21%7%
85
December1st to 15thDay
36%15%30%13%31
60
16th to endDay
31%15%40%11%1
85
January1st to 15thNight
25%12%31%22%6%
900
16th to endNight
20%10%35%24%7%1
960
February1st to 15thNight
19%10%34%26%8%
770
16th to endNight
22%10%27%29%9%
631
March1st to 15thNight
17%7%31%31%11%1
720
16th to endNight
17%6%25%35%13%1
715
April1st to 15thNight
24%6%26%32%9%
539
16th to endNight
18%5%27%34%12%1
540
May1st to 15thNight
17%225%37%16%
540
16th to endNight
12%321%35%23%2
563
June1st to 15thNight
17%219%37%22%1
468
16th to endNight
10%118%42%25%2
476
July1st to 15thNight
11%13%40%30%4
510
16th to endNight
8%116%38%30%4
564
August1st to 15thNight
9%113%41%30%4
539
16th to endNight
15%214%36%28%3
573
September1st to 15thNight
17%216%30%26%6%
597
16th to endNight
19%416%30%23%6%
693
October1st to 15thNight
27%6%20%28%16%1
660
16th to endNight
30%8%27%25%6%
704
November1st to 15thNight
27%10%27%26%7%1
700
16th to endNight
30%14%28%21%5%
759
December1st to 15thNight
28%18%31%17%3
900
16th to endNight
28%10%35%21%31
960
Page generated at 2017-09-25 09:02:26. Version ac04

Copyright 2017 A. Danko


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