Bremen
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bremen 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
37%
15938
16%
46892
11%
15896
43%
15896
22%
32173

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
16%
900
10%
2506
3%
895
22%
895
13%
1982
January16th to endNight
18%
960
10%
2688
4%
960
23%
960
13%
2110
February1st to 15thNight
20%
701
10%
2145
4%
701
27%
701
14%
1603
February16th to endNight
21%
631
14%
1893
5%
631
30%
631
15%
1397
March1st to 15thNight
27%
720
13%
2148
9%
720
31%
720
18%
1548
March16th to endNight
29%
711
16%
2055
8%
711
37%
711
20%
1442
April1st to 15thNight
30%
539
14%
1797
9%
539
38%
539
19%
1220
April16th to endNight
33%
540
20%
1676
11%
540
43%
540
23%
1099
May1st to 15thNight
34%
540
14%
1620
7%
540
40%
540
20%
1149
May16th to endNight
50%
562
16%
1580
12%
561
53%
561
30%
1012
June1st to 15thNight
55%
540
17%
1440
12%
540
60%
540
36%
896
June16th to endNight
52%
540
16%
1440
10%
540
57%
540
34%
923
July1st to 15thNight
66%
510
17%
1360
14%
510
67%
510
39%
822
July16th to endNight
72%
564
22%
1419
17%
531
74%
531
41%
823
August1st to 15thNight
74%
539
22%
1609
20%
536
76%
536
40%
894
August16th to endNight
65%
573
20%
1878
19%
573
69%
573
33%
1087
September1st to 15thNight
62%
600
27%
1860
24%
600
66%
600
35%
1057
September16th to endNight
60%
693
28%
1914
21%
693
63%
693
37%
1135
October1st to 15thNight
49%
660
28%
1821
20%
660
55%
660
34%
1104
October16th to endNight
27%
704
16%
2288
10%
704
36%
704
18%
1548
November1st to 15thNight
34%
700
22%
2276
16%
700
44%
700
24%
1444
November16th to endNight
26%
720
14%
2340
10%
720
33%
720
13%
1721
December1st to 15thNight
18%
831
8%
2451
3%
831
23%
831
12%
1932
December16th to endNight
15%
960
8%
2688
2%
960
21%
960
10%
2225

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%8%36%5%3445%7%34%
48044
Night
15%8%36%5%24446%36%
47062
Cloud CoverDay
14%8%36%5%3445%7%34%
48053
Night
15%8%36%5%2445%6%36%
47067
TransparencyDay
48%5%12%20%12%1
47732
Night
47%411%21%12%1
46892
SeeingDay
17%6%24%25%18%7%
5946
Night
20%7%27%29%13%1
15942

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
19%15%48%7%4435%5%21%
1432
16th to endDay
13%17%8%10%8%35%445%17%
1536
February1st to 15thDay
14%16%6%9%7%44446%21%
1715
16th to endDay
15%12%7%10%6%3445%7%22%
1580
March1st to 15thDay
18%11%5%8%5%3345%7%24%
1802
16th to endDay
19%9%36%5%35%446%30%
2180
April1st to 15thDay
19%10%46%5%2345%5%31%
2151
16th to endDay
18%7%25%5%24447%37%
2283
May1st to 15thDay
20%7%35%5%3445%7%31%
2331
16th to endDay
13%5%25%6%4445%6%40%
2533
June1st to 15thDay
11%425%5%35%46%7%43%
2520
16th to endDay
10%5%15%5%46%5%7%9%39%
2520
July1st to 15thDay
9%5%25%4345%5%9%44%
2520
16th to endDay
7%3245%45%6%6%10%42%
2652
August1st to 15thDay
7%3245%45%5%6%8%45%
2340
16th to endDay
11%416%435%45%8%43%
2321
September1st to 15thDay
13%42443445%7%44%
2088
16th to endDay
12%425%5%3446%8%43%
1905
October1st to 15thDay
15%5%25%42445%6%42%
1807
16th to endDay
22%7%35%5%245%5%6%31%
1584
November1st to 15thDay
15%8%45%422446%40%
1582
16th to endDay
19%13%5%7%5%34446%25%
1620
December1st to 15thDay
19%16%7%8%6%34336%20%
1506
16th to endDay
22%17%6%8%6%3335%5%17%
1536
January1st to 15thNight
21%13%48%6%24445%23%
2506
16th to endNight
15%13%8%8%7%35%446%22%
2688
February1st to 15thNight
17%12%6%7%6%34445%28%
2143
16th to endNight
16%13%6%8%6%33346%27%
1893
March1st to 15thNight
17%10%46%5%34446%32%
2135
16th to endNight
16%7%36%5%3446%7%33%
2055
April1st to 15thNight
20%7%345%345%5%6%34%
1797
16th to endNight
18%7%24435%345%40%
1676
May1st to 15thNight
20%7%35%5%3436%6%32%
1620
16th to endNight
12%6%24434446%44%
1578
June1st to 15thNight
9%425%42345%8%49%
1440
16th to endNight
10%415%5%235%7%9%43%
1440
July1st to 15thNight
6%3245%3445%9%51%
1440
16th to endNight
7%3133345%6%10%50%
1515
August1st to 15thNight
5%3133345%6%10%51%
1620
16th to endNight
10%314425%45%7%50%
1878
September1st to 15thNight
12%324322337%52%
1860
16th to endNight
12%5%23313447%51%
1914
October1st to 15thNight
13%5%2342335%6%50%
1821
16th to endNight
21%8%36%42343437%
2288
November1st to 15thNight
14%8%35%42445%5%40%
2276
16th to endNight
20%13%47%5%34446%26%
2340
December1st to 15thNight
20%15%6%8%6%34435%22%
2451
16th to endNight
23%15%5%8%6%24445%17%
2688

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
19%15%5%8%7%3435%6%20%
1432
16th to endDay
13%16%8%11%7%35%446%18%
1536
February1st to 15thDay
14%16%6%9%8%35%346%21%
1715
16th to endDay
15%11%8%10%7%3445%6%22%
1580
March1st to 15thDay
18%11%5%8%6%2445%7%23%
1812
16th to endDay
19%9%36%5%34446%30%
2179
April1st to 15thDay
19%10%46%5%2345%6%31%
2151
16th to endDay
18%7%25%5%24447%36%
2283
May1st to 15thDay
20%8%36%5%3445%7%31%
2331
16th to endDay
13%5%25%6%35%45%6%40%
2533
June1st to 15thDay
11%425%435%5%6%7%43%
2520
16th to endDay
9%4245%36%5%7%9%38%
2520
July1st to 15thDay
9%5%245%345%6%8%44%
2520
16th to endDay
6%3246%36%7%6%11%42%
2652
August1st to 15thDay
7%315%6%45%5%5%9%45%
2340
16th to endDay
10%426%5%35%45%9%43%
2321
September1st to 15thDay
13%42443445%7%44%
2088
16th to endDay
11%425%5%3445%8%43%
1905
October1st to 15thDay
14%6%25%424446%42%
1807
16th to endDay
21%7%25%6%335%5%6%31%
1584
November1st to 15thDay
15%7%36%423446%40%
1582
16th to endDay
20%12%47%5%3435%7%25%
1620
December1st to 15thDay
18%16%6%8%6%34336%20%
1506
16th to endDay
23%16%6%9%6%33345%17%
1536
January1st to 15thNight
21%13%5%8%6%35%435%23%
2506
16th to endNight
15%13%7%9%7%34446%22%
2688
February1st to 15thNight
17%12%6%7%6%24445%28%
2136
16th to endNight
17%12%6%8%6%33346%27%
1893
March1st to 15thNight
17%9%46%435%35%6%32%
2148
16th to endNight
16%7%36%6%3445%7%34%
2055
April1st to 15thNight
19%7%345%3445%7%34%
1797
16th to endNight
18%7%33435%345%40%
1676
May1st to 15thNight
20%7%35%5%2445%6%32%
1619
16th to endNight
12%5%35%425%35%7%43%
1578
June1st to 15thNight
9%415%43245%8%48%
1440
16th to endNight
10%425%5%3447%9%43%
1440
July1st to 15thNight
5%3245%3346%8%51%
1440
16th to endNight
6%314325%5%6%11%51%
1515
August1st to 15thNight
5%213425%5%7%9%51%
1620
16th to endNight
10%31442445%7%49%
1878
September1st to 15thNight
12%414322337%52%
1860
16th to endNight
12%5%2331345%6%51%
1914
October1st to 15thNight
13%5%2442335%5%50%
1821
16th to endNight
20%8%36%5%2344437%
2288
November1st to 15thNight
13%9%36%42445%5%41%
2276
16th to endNight
20%12%47%5%24346%26%
2340
December1st to 15thNight
20%15%6%8%6%34435%22%
2451
16th to endNight
23%15%5%9%6%24445%17%
2688

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
64%314%11%5%
1433
16th to endDay
67%310%12%4
1536
February1st to 15thDay
64%410%13%6%
1717
16th to endDay
62%412%16%4
1580
March1st to 15thDay
59%5%13%14%6%
1812
16th to endDay
53%5%12%21%5%
2180
April1st to 15thDay
53%410%19%12%
2151
16th to endDay
46%413%18%11%4
2283
May1st to 15thDay
52%6%11%21%8%
2331
16th to endDay
43%5%11%23%13%2
2537
June1st to 15thDay
37%5%11%24%18%1
2520
16th to endDay
38%7%14%20%17%1
2520
July1st to 15thDay
37%5%11%23%19%2
2371
16th to endDay
33%8%16%24%15%2
2485
August1st to 15thDay
34%7%13%25%16%2
2327
16th to endDay
37%6%12%23%15%4
2321
September1st to 15thDay
38%5%11%21%19%2
2088
16th to endDay
37%5%10%26%18%2
1905
October1st to 15thDay
41%410%24%16%1
1807
16th to endDay
51%5%12%19%9%
1584
November1st to 15thDay
44%410%22%16%2
1582
16th to endDay
57%413%18%5%
1620
December1st to 15thDay
65%310%15%4
1506
16th to endDay
69%412%9%3
1536
January1st to 15thNight
62%410%14%7%
2506
16th to endNight
62%313%15%4
2688
February1st to 15thNight
57%413%16%7%
2145
16th to endNight
58%211%19%7%
1893
March1st to 15thNight
53%412%18%9%2
2148
16th to endNight
49%5%12%21%8%1
2055
April1st to 15thNight
48%5%10%19%15%
1797
16th to endNight
45%49%20%15%4
1676
May1st to 15thNight
51%5%10%22%9%1
1620
16th to endNight
39%5%13%23%15%2
1580
June1st to 15thNight
33%5%11%28%19%1
1440
16th to endNight
34%6%16%22%16%1
1440
July1st to 15thNight
30%5%14%25%19%4
1360
16th to endNight
27%6%14%26%20%3
1419
August1st to 15thNight
26%6%13%28%22%2
1609
16th to endNight
31%6%11%23%21%5%
1878
September1st to 15thNight
32%310%26%21%4
1860
16th to endNight
32%49%27%22%2
1914
October1st to 15thNight
35%38%29%22%
1821
16th to endNight
50%311%23%10%1
2288
November1st to 15thNight
43%310%23%16%2
2276
16th to endNight
58%312%18%6%
2340
December1st to 15thNight
63%410%16%5%
2451
16th to endNight
69%410%11%4
2688

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%20%33%16%7%1
90
16th to endDay
21%14%39%21%11
96
February1st to 15thDay
26%17%43%11%1
90
16th to endDay
23%7%37%19%11%1
81
March1st to 15thDay
31%18%26%19%3
102
16th to endDay
30%6%31%21%8%1
288
April1st to 15thDay
25%10%32%22%7%1
270
16th to endDay
22%8%28%22%12%5%
270
May1st to 15thDay
28%6%27%21%10%4
288
16th to endDay
17%6%27%24%17%6%
433
June1st to 15thDay
12%427%30%18%6%
495
16th to endDay
14%6%28%25%17%7%
495
July1st to 15thDay
14%222%29%18%12%
475
16th to endDay
8%218%31%26%12%
512
August1st to 15thDay
8%12%27%32%17%
313
16th to endDay
14%214%25%29%14%
332
September1st to 15thDay
16%313%24%27%13%
315
16th to endDay
11%5%12%25%34%10%
287
October1st to 15thDay
15%8%20%30%19%5%
252
16th to endDay
25%12%28%31%3
96
November1st to 15thDay
6%10%26%33%20%3
90
16th to endDay
32%11%34%18%3
90
December1st to 15thDay
18%18%42%14%5%
90
16th to endDay
27%21%42%7%1
96
January1st to 15thNight
28%14%34%18%4
900
16th to endNight
21%13%36%26%3
960
February1st to 15thNight
25%10%35%24%3
704
16th to endNight
23%11%35%24%4
631
March1st to 15thNight
23%9%33%25%7%
720
16th to endNight
20%8%34%29%6%
711
April1st to 15thNight
22%11%33%26%6%
539
16th to endNight
22%6%33%25%11%1
540
May1st to 15thNight
24%428%31%10%
540
16th to endNight
14%424%39%17%
563
June1st to 15thNight
10%224%45%16%
540
16th to endNight
11%225%36%22%1
540
July1st to 15thNight
8%114%46%26%2
510
16th to endNight
7%111%42%33%3
564
August1st to 15thNight
6%19%47%30%5%
539
16th to endNight
10%113%35%34%4
573
September1st to 15thNight
15%214%34%29%4
600
16th to endNight
15%315%31%29%4
693
October1st to 15thNight
15%5%25%32%18%3
660
16th to endNight
24%11%31%23%8%
704
November1st to 15thNight
18%10%32%26%10%1
700
16th to endNight
28%11%27%24%7%
720
December1st to 15thNight
28%14%31%20%4
831
16th to endNight
30%10%35%19%3
960
Page generated at 2017-09-25 09:02:19. Version ac04

Copyright 2017 A. Danko


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