TheDamObservatory-Lake Tschida
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the TheDamObservatory-Lake Tschida clear sky chart from 2005-11-05 to 2018-02-13.

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
40%
16886
18%
48872
10%
16845
46%
16845
28%
31170

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
28%
973
14%
2716
6%
970
34%
970
21%
1906
January16th to endNight
28%
1040
15%
2912
7%
1040
34%
1040
21%
2038
February1st to 15thNight
30%
874
11%
2527
5%
874
35%
874
18%
1822
February16th to endNight
35%
632
15%
1894
9%
632
42%
632
24%
1268
March1st to 15thNight
32%
720
13%
2160
7%
720
38%
720
21%
1480
March16th to endNight
36%
589
13%
2026
9%
589
43%
589
20%
1350
April1st to 15thNight
33%
539
18%
1798
11%
539
46%
539
25%
1099
April16th to endNight
36%
540
16%
1636
13%
540
42%
540
23%
1108
May1st to 15thNight
45%
540
16%
1518
9%
540
49%
540
31%
968
May16th to endNight
44%
563
13%
1498
6%
561
45%
561
30%
974
June1st to 15thNight
45%
540
11%
1302
5%
540
49%
540
36%
850
June16th to endNight
54%
540
13%
1302
7%
540
56%
540
51%
742
July1st to 15thNight
60%
510
15%
1360
9%
510
62%
510
51%
728
July16th to endNight
66%
564
22%
1416
13%
531
67%
531
56%
733
August1st to 15thNight
62%
539
23%
1474
15%
536
67%
536
48%
808
August16th to endNight
62%
573
29%
1815
26%
573
72%
573
48%
884
September1st to 15thNight
58%
540
24%
1823
22%
540
67%
540
41%
922
September16th to endNight
50%
537
28%
1980
25%
537
61%
537
35%
1014
October1st to 15thNight
42%
633
24%
2073
18%
633
48%
633
27%
1235
October16th to endNight
41%
960
24%
2496
10%
960
48%
960
31%
1599
November1st to 15thNight
37%
950
23%
2470
10%
950
45%
950
30%
1589
November16th to endNight
33%
975
20%
2729
9%
975
42%
975
27%
1774
December1st to 15thNight
29%
975
11%
2925
6%
975
36%
975
18%
2083
December16th to endNight
28%
1040
16%
3022
8%
1040
36%
1040
17%
2196

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
9%7%35%5%3445%7%43%
49159
Night
8%7%36%5%3445%7%43%
49039
Cloud CoverDay
9%7%36%5%2445%7%43%
49168
Night
8%7%36%5%3445%7%43%
49043
Cloud CoverDay
9%7%35%5%3445%7%43%
49169
Night
8%7%36%5%3445%7%43%
49044
Cloud CoverDay
10%7%36%5%3445%7%43%
49167
Night
8%7%36%5%3445%7%43%
49044
TransparencyDay
40%415%25%12%1
48843
Night
39%5%14%25%12%1
48872
SeeingDay
13%7%29%31%15%2
6609
Night
11%8%31%35%11%1
16893

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
5%9%5%9%6%35%46%7%34%
1552
16th to endDay
5%9%6%8%8%46%6%5%7%32%
1664
February1st to 15thDay
9%10%5%9%7%35%45%5%32%
1609
16th to endDay
5%11%7%12%9%35%5%46%27%
1580
March1st to 15thDay
8%8%5%8%6%34447%36%
1790
16th to endDay
14%11%47%6%35%45%6%30%
2194
April1st to 15thDay
10%7%47%5%3445%7%38%
2150
16th to endDay
17%9%36%5%2445%6%33%
2323
May1st to 15thDay
13%9%26%424446%41%
2430
16th to endDay
15%7%35%5%25%5%5%8%36%
2616
June1st to 15thDay
15%4245%3445%7%41%
2653
16th to endDay
6%3135%245%5%8%52%
2653
July1st to 15thDay
5%21332446%9%55%
2520
16th to endDay
5%21342445%8%56%
2656
August1st to 15thDay
8%3244345%6%8%50%
2476
16th to endDay
6%423423336%59%
2387
September1st to 15thDay
8%41432435%5%55%
2136
16th to endDay
12%5%13421235%56%
1980
October1st to 15thDay
12%6%35%5%23346%47%
1872
16th to endDay
11%9%3442335%8%42%
1728
November1st to 15thDay
8%7%345%35%45%6%45%
1718
16th to endDay
6%9%48%6%3437%8%36%
1557
December1st to 15thDay
6%10%5%8%7%36%5%5%7%31%
1365
16th to endDay
9%11%49%7%4445%8%30%
1550
January1st to 15thNight
6%8%5%8%8%36%5%5%6%34%
2716
16th to endNight
410%5%9%6%45%5%5%8%33%
2912
February1st to 15thNight
9%8%5%9%7%45%5%5%6%31%
2524
16th to endNight
6%9%48%7%345%5%6%38%
1894
March1st to 15thNight
6%8%47%6%46%5%5%6%37%
2147
16th to endNight
13%9%36%6%245%6%6%35%
2026
April1st to 15thNight
8%7%26%435%5%7%7%40%
1798
16th to endNight
13%6%45%5%35%5%5%7%37%
1636
May1st to 15thNight
10%5%25%5%35%45%8%42%
1518
16th to endNight
13%4145%245%7%9%41%
1497
June1st to 15thNight
10%32343447%8%45%
1302
16th to endNight
5%21321446%9%57%
1302
July1st to 15thNight
321332235%8%61%
1440
16th to endNight
412313448%65%
1512
August1st to 15thNight
5%31333345%7%59%
1482
16th to endNight
5%21231335%6%63%
1815
September1st to 15thNight
7%414312347%60%
1823
16th to endNight
10%413313247%56%
1980
October1st to 15thNight
14%5%14324447%47%
2073
16th to endNight
9%7%346%2445%8%44%
2496
November1st to 15thNight
7%7%35%4245%6%7%44%
2470
16th to endNight
7%7%26%6%3446%8%41%
2729
December1st to 15thNight
7%10%49%7%35%5%5%6%32%
2925
16th to endNight
9%12%5%8%7%34446%31%
3022

Percentage Cloud Cover NW (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
5%9%5%9%6%35%46%7%34%
1553
16th to endDay
5%9%5%8%8%37%6%5%7%32%
1664
February1st to 15thDay
9%10%5%8%8%35%36%5%32%
1609
16th to endDay
5%11%7%12%9%35%5%5%6%28%
1580
March1st to 15thDay
7%9%47%7%35%447%37%
1800
16th to endDay
15%11%47%6%35%446%30%
2192
April1st to 15thDay
10%7%47%425%45%7%38%
2150
16th to endDay
17%9%35%5%2446%6%33%
2323
May1st to 15thDay
13%8%35%42345%6%41%
2430
16th to endDay
15%6%26%5%345%6%8%36%
2616
June1st to 15thDay
15%425%5%3445%7%40%
2653
16th to endDay
6%3144245%5%8%53%
2653
July1st to 15thDay
5%2133245%5%9%54%
2520
16th to endDay
5%21343445%8%56%
2656
August1st to 15thDay
7%32442447%8%50%
2476
16th to endDay
6%423413336%59%
2387
September1st to 15thDay
8%414424445%55%
2136
16th to endDay
12%5%13312235%57%
1980
October1st to 15thDay
12%6%345%23346%47%
1872
16th to endDay
10%9%35%42435%8%43%
1728
November1st to 15thDay
8%8%345%24447%45%
1718
16th to endDay
6%9%49%7%3436%9%36%
1557
December1st to 15thDay
6%11%5%8%7%35%5%6%6%32%
1365
16th to endDay
9%12%49%7%4435%7%31%
1550
January1st to 15thNight
6%8%5%8%7%35%5%5%7%34%
2716
16th to endNight
410%5%9%6%45%5%6%9%33%
2912
February1st to 15thNight
9%8%5%9%8%35%5%5%7%31%
2517
16th to endNight
5%9%5%7%8%25%45%6%38%
1894
March1st to 15thNight
6%9%47%7%46%5%5%5%37%
2160
16th to endNight
13%9%45%6%245%6%6%35%
2024
April1st to 15thNight
8%7%35%5%25%6%7%7%40%
1798
16th to endNight
14%5%45%6%35%45%7%37%
1636
May1st to 15thNight
10%6%26%435%45%8%42%
1517
16th to endNight
13%5%25%43446%9%41%
1498
June1st to 15thNight
10%42442447%9%45%
1302
16th to endNight
431222346%8%58%
1302
July1st to 15thNight
321342335%8%61%
1440
16th to endNight
4112313448%65%
1512
August1st to 15thNight
5%31233435%7%59%
1482
16th to endNight
5%22313447%63%
1815
September1st to 15thNight
7%323312347%60%
1823
16th to endNight
10%414312247%56%
1980
October1st to 15thNight
14%5%13424447%47%
2073
16th to endNight
9%7%25%5%3345%8%44%
2496
November1st to 15thNight
7%7%35%5%2446%7%44%
2470
16th to endNight
7%7%36%6%345%6%8%41%
2729
December1st to 15thNight
7%11%5%8%7%35%45%6%32%
2925
16th to endNight
9%12%5%8%7%345%46%31%
3022

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 15thDay
5%9%5%10%6%35%5%6%7%34%
1552
16th to endDay
5%9%5%8%8%46%5%5%7%32%
1664
February1st to 15thDay
9%10%5%9%7%35%45%5%32%
1609
16th to endDay
5%11%6%12%10%35%446%28%
1580
March1st to 15thDay
7%9%5%8%6%35%447%37%
1800
16th to endDay
14%11%47%7%25%447%30%
2194
April1st to 15thDay
10%7%47%435%45%7%38%
2150
16th to endDay
17%9%35%5%2445%6%33%
2323
May1st to 15thDay
13%9%25%424446%41%
2430
16th to endDay
15%6%25%5%345%6%8%36%
2616
June1st to 15thDay
15%5%245%3445%7%40%
2653
16th to endDay
6%4135%2445%9%52%
2653
July1st to 15thDay
5%2133245%6%8%55%
2520
16th to endDay
5%21343445%8%56%
2656
August1st to 15thDay
7%3143345%6%8%50%
2476
16th to endDay
6%423423236%59%
2387
September1st to 15thDay
8%42343435%5%55%
2136
16th to endDay
12%5%13421235%56%
1980
October1st to 15thDay
12%6%245%23346%47%
1872
16th to endDay
10%9%4442335%8%42%
1728
November1st to 15thDay
8%7%345%24446%45%
1718
16th to endDay
6%9%48%7%3336%9%36%
1557
December1st to 15thDay
6%10%6%8%7%35%5%5%7%32%
1365
16th to endDay
9%11%5%8%7%4445%7%30%
1550
January1st to 15thNight
6%8%5%8%8%36%5%5%6%34%
2716
16th to endNight
410%49%6%45%5%6%8%33%
2912
February1st to 15thNight
9%8%49%7%45%5%5%7%31%
2517
16th to endNight
5%9%5%7%7%4445%7%38%
1894
March1st to 15thNight
6%8%5%7%6%46%5%6%6%37%
2160
16th to endNight
13%9%35%6%2446%7%35%
2026
April1st to 15thNight
8%7%26%5%25%6%7%7%40%
1798
16th to endNight
13%6%46%5%35%45%7%37%
1636
May1st to 15thNight
10%6%25%5%25%5%5%8%42%
1517
16th to endNight
13%5%135%3447%8%41%
1497
June1st to 15thNight
10%32443447%8%45%
1302
16th to endNight
5%31222347%8%58%
1302
July1st to 15thNight
321342235%8%61%
1440
16th to endNight
4112313448%65%
1512
August1st to 15thNight
5%31233345%7%59%
1482
16th to endNight
43132335%6%63%
1815
September1st to 15thNight
7%323312347%59%
1823
16th to endNight
10%414313237%56%
1980
October1st to 15thNight
13%6%13423446%47%
2073
16th to endNight
9%7%25%5%2345%8%44%
2496
November1st to 15thNight
7%7%35%4245%6%8%44%
2470
16th to endNight
7%7%36%6%25%45%8%41%
2729
December1st to 15thNight
7%11%48%7%45%5%5%6%33%
2925
16th to endNight
9%12%5%8%7%34446%31%
3022

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
6%9%5%10%5%36%46%8%34%
1552
16th to endDay
5%9%6%8%7%46%6%5%7%32%
1664
February1st to 15thDay
9%10%5%8%8%45%5%45%32%
1609
16th to endDay
6%11%7%12%8%36%35%6%28%
1580
March1st to 15thDay
8%8%5%8%7%34447%37%
1800
16th to endDay
15%11%47%6%35%446%30%
2192
April1st to 15thDay
11%7%37%5%3445%8%38%
2150
16th to endDay
18%8%36%5%3445%6%32%
2323
May1st to 15thDay
14%8%35%424346%41%
2430
16th to endDay
16%6%25%5%345%6%7%36%
2616
June1st to 15thDay
16%4245%35%45%7%41%
2653
16th to endDay
7%32333446%8%52%
2653
July1st to 15thDay
5%21343446%8%55%
2520
16th to endDay
5%31342446%7%56%
2656
August1st to 15thDay
8%3234245%5%8%51%
2476
16th to endDay
7%424313236%59%
2387
September1st to 15thDay
9%324423345%55%
2136
16th to endDay
13%5%13312335%56%
1980
October1st to 15thDay
12%6%25%5%13346%46%
1872
16th to endDay
11%8%3442346%7%42%
1728
November1st to 15thDay
9%7%35%5%2345%6%45%
1718
16th to endDay
6%10%48%7%2437%8%36%
1557
December1st to 15thDay
7%10%5%8%8%35%5%5%8%31%
1365
16th to endDay
10%11%49%7%4335%7%30%
1550
January1st to 15thNight
6%9%5%8%6%46%5%5%7%34%
2716
16th to endNight
411%5%8%7%445%6%8%34%
2912
February1st to 15thNight
10%7%5%9%7%35%5%5%7%31%
2517
16th to endNight
6%9%47%6%4445%7%38%
1894
March1st to 15thNight
7%8%47%6%36%5%5%6%36%
2160
16th to endNight
13%9%36%425%45%7%35%
2026
April1st to 15thNight
8%7%26%425%6%7%7%41%
1798
16th to endNight
14%7%35%5%345%5%6%37%
1636
May1st to 15thNight
10%6%24435%46%8%42%
1517
16th to endNight
14%424425%5%6%8%42%
1497
June1st to 15thNight
10%4244245%7%7%46%
1302
16th to endNight
5%21322347%8%58%
1302
July1st to 15thNight
42331335%7%62%
1440
16th to endNight
41221336%8%65%
1512
August1st to 15thNight
5%312324447%59%
1482
16th to endNight
5%21232335%6%63%
1815
September1st to 15thNight
8%313312347%60%
1823
16th to endNight
10%414323246%56%
1980
October1st to 15thNight
14%5%1433345%7%46%
2073
16th to endNight
9%8%25%42345%7%44%
2496
November1st to 15thNight
8%7%35%5%2445%8%44%
2470
16th to endNight
7%7%36%6%35%5%5%8%40%
2729
December1st to 15thNight
7%11%49%7%35%5%5%7%32%
2925
16th to endNight
10%12%5%9%7%34446%30%
3022

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
48%418%18%8%
1553
16th to endDay
49%7%15%19%7%
1664
February1st to 15thDay
53%414%20%6%
1610
16th to endDay
55%413%18%7%
1580
March1st to 15thDay
47%5%15%22%8%
1800
16th to endDay
54%417%19%3
2194
April1st to 15thDay
43%416%25%9%
2150
16th to endDay
50%5%13%21%8%1
2323
May1st to 15thDay
43%412%27%12%
2430
16th to endDay
45%5%16%23%8%
2620
June1st to 15thDay
42%5%17%25%8%
2653
16th to endDay
28%6%19%30%13%1
2653
July1st to 15thDay
24%5%15%32%15%5%
2371
16th to endDay
25%5%14%31%20%3
2489
August1st to 15thDay
29%5%15%26%17%4
2460
16th to endDay
27%311%31%21%4
2387
September1st to 15thDay
30%412%32%16%3
2136
16th to endDay
31%311%34%18%1
1980
October1st to 15thDay
38%314%26%15%1
1872
16th to endDay
40%5%15%24%11%1
1728
November1st to 15thDay
38%413%27%14%1
1718
16th to endDay
44%5%18%20%9%1
1557
December1st to 15thDay
51%6%14%21%5%
1365
16th to endDay
53%415%17%8%
1550
January1st to 15thNight
48%5%16%18%9%1
2716
16th to endNight
46%6%15%22%7%1
2912
February1st to 15thNight
51%414%19%8%
2527
16th to endNight
45%415%22%10%
1894
March1st to 15thNight
46%5%14%24%8%
2160
16th to endNight
46%5%18%21%7%
2026
April1st to 15thNight
38%6%13%27%12%2
1798
16th to endNight
45%5%13%20%12%1
1636
May1st to 15thNight
37%5%13%29%14%
1518
16th to endNight
37%6%19%24%10%
1498
June1st to 15thNight
33%7%17%31%9%1
1302
16th to endNight
22%5%21%32%16%2
1302
July1st to 15thNight
21%315%35%16%6%
1360
16th to endNight
17%413%35%22%5%
1416
August1st to 15thNight
23%415%29%20%6%
1474
16th to endNight
21%310%35%24%5%
1815
September1st to 15thNight
24%411%33%21%3
1823
16th to endNight
29%311%34%19%1
1980
October1st to 15thNight
36%411%27%18%1
2073
16th to endNight
38%313%28%14%2
2496
November1st to 15thNight
37%413%25%16%2
2470
16th to endNight
39%5%18%22%11%1
2729
December1st to 15thNight
51%5%16%20%5%
2925
16th to endNight
53%412%19%8%
3022

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
12%10%31%28%9%7%
135
16th to endDay
6%12%33%28%11%7%
144
February1st to 15thDay
15%6%48%27%2
126
16th to endDay
17%7%28%30%14%1
81
March1st to 15thDay
17%8%38%24%6%3
90
16th to endDay
15%7%35%29%9%3
192
April1st to 15thDay
14%17%35%25%6%
269
16th to endDay
22%9%26%24%15%2
433
May1st to 15thDay
17%9%29%26%14%2
468
16th to endDay
17%5%29%30%14%2
517
June1st to 15thDay
15%8%28%29%15%2
495
16th to endDay
9%9%31%34%13%1
495
July1st to 15thDay
6%427%38%20%2
475
16th to endDay
6%424%42%19%2
515
August1st to 15thDay
10%224%36%20%5%
493
16th to endDay
8%421%36%24%4
427
September1st to 15thDay
11%6%27%30%18%5%
291
16th to endDay
17%334%28%13%2
135
October1st to 15thDay
13%11%38%23%11%1
135
16th to endDay
19%9%29%29%9%3
144
November1st to 15thDay
16%234%24%17%4
135
16th to endDay
18%11%31%29%8%
135
December1st to 15thDay
13%14%41%20%9%
135
16th to endDay
11%12%45%22%7%
144
January1st to 15thNight
11%12%36%29%9%1
975
16th to endNight
10%13%39%28%9%
1040
February1st to 15thNight
12%10%32%31%10%1
879
16th to endNight
9%6%35%34%11%1
632
March1st to 15thNight
10%10%36%29%10%2
720
16th to endNight
18%432%34%8%
589
April1st to 15thNight
11%7%38%32%8%
539
16th to endNight
17%7%30%29%14%
540
May1st to 15thNight
14%6%28%38%11%
540
16th to endNight
16%428%36%13%
563
June1st to 15thNight
12%5%30%39%11%
540
16th to endNight
7%5%29%44%13%
540
July1st to 15thNight
5%227%46%17%
510
16th to endNight
4223%51%18%
564
August1st to 15thNight
7%123%51%16%
539
16th to endNight
5%225%45%18%2
573
September1st to 15thNight
9%324%44%16%2
540
16th to endNight
11%429%36%17%1
537
October1st to 15thNight
17%9%25%35%10%
633
16th to endNight
14%9%28%34%12%1
960
November1st to 15thNight
11%10%33%31%11%
950
16th to endNight
11%10%37%31%8%
975
December1st to 15thNight
13%10%34%32%8%1
975
16th to endNight
15%11%30%31%10%
1040
Page generated at 2018-02-13 18:46:00. Version ac04

Copyright 2018 A. Danko


TheDamObservatory-Lake Tschida Clear Sky Chart |Charts Home