Sommers-Bausch Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sommers-Bausch Observatory clear sky chart from 2005-11-06 to 2024-03-28.

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
54%
24848
28%
80181
19%
24769
64%
24769
38%
41231

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
42%
935
32%
4325
17%
926
58%
926
27%
2044
January11th to 20thNight
36%
908
35%
4226
15%
897
53%
897
32%
1653
January21st to endNight
41%
826
22%
4263
18%
814
58%
814
23%
2036
February1st to 10thNight
34%
760
28%
2470
12%
760
54%
760
32%
1301
February11th to 20thNight
39%
741
28%
2258
15%
740
53%
740
33%
1230
February21st to endNight
39%
628
33%
1884
14%
628
58%
628
38%
998
March1st to 10thNight
45%
760
30%
2280
15%
760
58%
760
40%
1201
March11th to 20thNight
51%
760
29%
2103
16%
760
60%
760
41%
1192
March21st to endNight
44%
690
26%
2125
14%
690
56%
690
35%
1176
April1st to 10thNight
43%
540
26%
1800
16%
540
59%
540
36%
936
April11th to 20thNight
42%
533
25%
1777
18%
533
55%
533
33%
971
April21st to endNight
45%
540
23%
1800
17%
540
56%
540
30%
1034
May1st to 10thNight
48%
540
19%
1671
16%
540
54%
540
28%
1029
May11th to 20thNight
58%
531
17%
1418
14%
531
59%
531
30%
915
May21st to endNight
60%
584
20%
1552
13%
582
66%
582
41%
895
June1st to 10thNight
71%
540
24%
1440
20%
540
72%
540
47%
780
June11th to 20thNight
70%
540
27%
1440
20%
540
74%
540
52%
761
June21st to endNight
76%
540
27%
1440
22%
540
78%
540
53%
751
July1st to 10thNight
76%
525
21%
1400
18%
525
77%
525
42%
811
July11th to 20thNight
83%
522
29%
1392
25%
522
84%
522
54%
707
July21st to endNight
80%
591
25%
1530
24%
558
80%
558
42%
856
August1st to 10thNight
79%
537
19%
1602
19%
534
79%
534
39%
883
August11th to 20thNight
81%
534
30%
1758
34%
534
82%
534
47%
842
August21st to endNight
80%
594
31%
1980
36%
594
81%
594
44%
977
September1st to 10thNight
76%
540
31%
1800
34%
540
81%
540
43%
882
September11th to 20thNight
72%
540
38%
1810
36%
540
79%
540
49%
826
September21st to endNight
68%
540
33%
1980
30%
540
77%
540
43%
915
October1st to 10thNight
61%
716
28%
2156
19%
716
68%
716
43%
1132
October11th to 20thNight
62%
720
35%
2160
21%
720
71%
720
52%
1025
October21st to endNight
50%
835
33%
2419
16%
835
61%
835
40%
1323
November1st to 10thNight
56%
925
34%
2405
17%
925
65%
925
54%
1238
November11th to 20thNight
45%
950
37%
2470
17%
950
57%
950
48%
1305
November21st to endNight
51%
950
31%
2588
15%
950
63%
950
46%
1377
December1st to 10thNight
45%
950
29%
2660
14%
950
57%
950
41%
1389
December11th to 20thNight
43%
949
30%
3107
15%
949
55%
949
37%
1563
December21st to endNight
39%
1034
20%
4692
11%
1026
54%
1026
24%
2277

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
5%5%244345%6%8%54%
78836
Night
45%2442345%7%60%
81220
TransparencyDay
27%7%11%23%23%9%
78543
Night
24%5%11%25%25%10%
81035
SeeingDay
8%8%26%33%19%6%
14682
Night
6%9%24%41%17%3
24897

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
1426%5%3445%8%60%
2538
11th to 20thDay
1425%5%4445%8%58%
2613
21st to endDay
16%35%43346%7%58%
3146
February1st to 10thDay
26%38%4245%46%56%
1710
11th to 20thDay
143442446%10%59%
1806
21st to endDay
26%37%42345%6%59%
1570
March1st to 10thDay
35%35%42446%8%55%
1900
11th to 20thDay
5%8%344334410%52%
2075
21st to endDay
5%8%35%4235%6%10%49%
2385
April1st to 10thDay
6%6%2332336%10%56%
2160
11th to 20thDay
9%8%35%3245%5%9%46%
2131
21st to endDay
9%7%345%35%5%6%7%47%
2160
May1st to 10thDay
12%7%245%35%6%7%8%40%
2285
11th to 20thDay
15%9%24425%5%7%8%38%
2478
21st to endDay
9%5%24436%6%7%10%43%
2724
June1st to 10thDay
5%4135%35%6%7%11%49%
2520
11th to 20thDay
7%313436%7%7%8%52%
2520
21st to endDay
4313436%7%9%10%50%
2520
July1st to 10thDay
7%4145%36%7%8%10%47%
2520
11th to 20thDay
5%213436%5%8%10%52%
2520
21st to endDay
6%3245%46%6%8%10%46%
2694
August1st to 10thDay
5%325%5%47%7%9%10%44%
2328
11th to 20thDay
5%313435%6%7%9%55%
2140
21st to endDay
5%313435%6%8%9%51%
2376
September1st to 10thDay
5%3233345%5%7%61%
2160
11th to 20thDay
6%31332445%8%60%
2149
21st to endDay
7%413323345%65%
1980
October1st to 10thDay
6%7%2432345%6%60%
1800
11th to 20thDay
4323423335%69%
1800
21st to endDay
5%7%14312346%64%
1918
November1st to 10thDay
2413222447%68%
1673
11th to 20thDay
342332346%8%63%
1710
21st to endDay
35%4432336%7%60%
1587
December1st to 10thDay
1425%423449%62%
1520
11th to 20thDay
25%23323348%63%
1926
21st to endDay
29%36%5%33447%54%
2794
January1st to 10thNight
16%46%5%33347%57%
4417
11th to 20thNight
1323335%45%9%64%
4384
21st to endNight
28%36%5%2335%6%58%
4521
February1st to 10thNight
17%35%5%24447%58%
2470
11th to 20thNight
15%46%43445%6%58%
2258
21st to endNight
27%36%423346%61%
1884
March1st to 10thNight
36%3443345%9%58%
2280
11th to 20thNight
6%8%23323346%61%
2103
21st to endNight
5%8%2442335%7%56%
2125
April1st to 10thNight
47%2432345%6%60%
1800
11th to 20thNight
9%7%2432335%6%55%
1777
21st to endNight
12%8%24423448%50%
1800
May1st to 10thNight
12%6%335%3445%8%46%
1671
11th to 20thNight
17%6%2342345%8%46%
1417
21st to endNight
8%41333345%8%57%
1552
June1st to 10thNight
6%31242346%9%60%
1440
11th to 20thNight
6%3122235%5%7%64%
1440
21st to endNight
421332345%9%63%
1440
July1st to 10thNight
7%313325%5%6%10%55%
1440
11th to 20thNight
222232447%9%64%
1440
21st to endNight
6%324335%6%7%10%52%
1620
August1st to 10thNight
4314435%5%7%10%54%
1611
11th to 20thNight
5%21332445%9%61%
1758
21st to endNight
43134345%5%7%60%
1980
September1st to 10thNight
7%21332445%7%62%
1800
11th to 20thNight
7%211213248%67%
1810
21st to endNight
7%21332335%5%66%
1980
October1st to 10thNight
7%6%12323445%63%
2156
11th to 20thNight
4413322445%70%
2160
21st to endNight
6%7%24413346%60%
2419
November1st to 10thNight
25%1322335%6%69%
2405
11th to 20thNight
25%24322346%66%
2470
21st to endNight
36%3331336%6%63%
2588
December1st to 10thNight
25%2442335%8%63%
2660
11th to 20thNight
25%2443445%9%58%
3271
21st to endNight
38%35%5%2445%6%54%
4873

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
23%5%11%27%23%10%
2539
11th to 20thDay
24%6%14%30%18%8%
2613
21st to endDay
24%7%10%31%24%5%
3146
February1st to 10thDay
29%5%12%26%19%9%
1710
11th to 20thDay
22%5%10%27%29%7%
1816
21st to endDay
26%5%10%22%26%12%
1570
March1st to 10thDay
26%5%10%27%25%7%
1900
11th to 20thDay
29%6%11%25%24%4
2075
21st to endDay
30%7%13%25%19%6%
2385
April1st to 10thDay
25%6%12%26%21%10%
2160
11th to 20thDay
35%6%11%21%19%8%
2134
21st to endDay
34%8%12%24%20%2
2160
May1st to 10thDay
39%9%12%22%14%4
2285
11th to 20thDay
42%9%14%21%12%2
2482
21st to endDay
33%10%14%23%13%6%
2724
June1st to 10thDay
26%10%16%22%18%8%
2520
11th to 20thDay
26%9%11%17%22%14%
2520
21st to endDay
24%8%12%20%25%11%
2520
July1st to 10thDay
29%10%13%19%19%11%
2451
11th to 20thDay
23%10%12%21%22%12%
2445
21st to endDay
30%11%14%23%15%7%
2544
August1st to 10thDay
31%13%15%20%14%7%
2313
11th to 20thDay
23%8%12%21%24%11%
2140
21st to endDay
25%8%11%21%25%10%
2376
September1st to 10thDay
23%6%8%21%24%18%
2160
11th to 20thDay
21%6%9%21%27%15%
2149
21st to endDay
22%46%20%37%10%
1980
October1st to 10thDay
25%6%10%21%28%11%
1800
11th to 20thDay
20%48%23%32%14%
1800
21st to endDay
23%38%26%26%13%
1918
November1st to 10thDay
17%410%24%31%14%
1673
11th to 20thDay
19%49%28%33%8%
1710
21st to endDay
24%38%22%30%13%
1587
December1st to 10thDay
21%6%12%30%22%9%
1520
11th to 20thDay
20%5%10%28%30%7%
1924
21st to endDay
28%412%21%27%8%
2794
January1st to 10thNight
27%49%26%28%6%
4417
11th to 20thNight
17%5%14%29%25%11%
4384
21st to endNight
27%5%11%30%21%6%
4521
February1st to 10thNight
28%311%26%24%7%
2470
11th to 20thNight
27%47%28%25%8%
2258
21st to endNight
26%36%24%27%14%
1884
March1st to 10thNight
25%47%26%29%9%
2280
11th to 20thNight
26%6%9%23%30%6%
2103
21st to endNight
29%5%11%27%23%5%
2125
April1st to 10thNight
26%5%11%24%23%11%
1800
11th to 20thNight
31%5%10%25%22%8%
1777
21st to endNight
35%5%10%24%22%5%
1800
May1st to 10thNight
36%8%13%22%17%5%
1671
11th to 20thNight
37%8%17%22%14%3
1418
21st to endNight
26%8%17%26%16%8%
1552
June1st to 10thNight
21%7%17%31%15%9%
1440
11th to 20thNight
19%6%13%19%23%21%
1440
21st to endNight
17%7%11%22%30%13%
1440
July1st to 10thNight
24%9%13%22%22%10%
1400
11th to 20thNight
16%7%13%27%23%14%
1392
21st to endNight
23%9%18%27%16%6%
1530
August1st to 10thNight
24%9%18%26%15%8%
1602
11th to 20thNight
20%5%11%26%25%13%
1758
21st to endNight
22%6%12%24%26%11%
1980
September1st to 10thNight
22%6%9%22%23%19%
1800
11th to 20thNight
18%5%9%24%26%18%
1810
21st to endNight
21%48%21%32%13%
1980
October1st to 10thNight
23%6%12%20%27%13%
2156
11th to 20thNight
17%411%21%30%17%
2160
21st to endNight
27%37%23%28%12%
2419
November1st to 10thNight
17%49%25%29%16%
2405
11th to 20thNight
20%37%28%33%9%
2470
21st to endNight
23%39%22%31%12%
2588
December1st to 10thNight
21%413%25%26%10%
2660
11th to 20thNight
22%5%10%26%31%6%
3272
21st to endNight
28%5%12%23%24%9%
4873

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
411%24%41%14%4
270
11th to 20thDay
5%11%38%36%9%1
270
21st to endDay
410%34%35%16%1
297
February1st to 10thDay
5%21%36%31%5%2
270
11th to 20thDay
412%40%37%6%1
270
21st to endDay
6%15%38%36%4
225
March1st to 10thDay
5%13%35%32%13%3
270
11th to 20thDay
11%13%33%31%11%2
445
21st to endDay
11%18%37%25%8%1
491
April1st to 10thDay
9%20%31%28%10%1
420
11th to 20thDay
12%19%31%28%8%1
412
21st to endDay
13%13%34%27%11%2
420
May1st to 10thDay
15%8%29%34%12%2
531
11th to 20thDay
19%6%24%28%19%4
625
21st to endDay
10%7%27%28%23%5%
679
June1st to 10thDay
6%320%33%27%10%
630
11th to 20thDay
6%425%38%20%6%
630
21st to endDay
5%323%36%24%8%
630
July1st to 10thDay
8%214%29%34%12%
621
11th to 20thDay
5%116%33%34%11%
618
21st to endDay
6%313%30%35%14%
636
August1st to 10thDay
6%420%36%25%10%
447
11th to 20thDay
5%222%33%29%8%
437
21st to endDay
6%221%37%27%7%
495
September1st to 10thDay
6%322%34%27%8%
450
11th to 20thDay
6%323%36%25%7%
439
21st to endDay
7%324%33%24%10%
270
October1st to 10thDay
9%7%20%27%23%13%
270
11th to 20thDay
37%29%37%19%4
270
21st to endDay
8%10%31%33%15%3
297
November1st to 10thDay
39%28%38%19%4
270
11th to 20thDay
8%10%27%38%14%3
270
21st to endDay
7%10%29%39%12%3
270
December1st to 10thDay
6%16%32%34%10%3
270
11th to 20thDay
413%31%42%9%
270
21st to endDay
6%15%33%36%8%2
297
January1st to 10thNight
318%28%39%10%3
950
11th to 20thNight
321%35%30%10%2
917
21st to endNight
414%31%41%8%1
836
February1st to 10thNight
417%38%34%7%1
760
11th to 20thNight
316%34%38%8%
744
21st to endNight
5%13%35%43%4
628
March1st to 10thNight
411%33%42%8%1
760
11th to 20thNight
9%9%26%43%11%1
760
21st to endNight
10%9%31%43%6%1
690
April1st to 10thNight
8%9%33%43%6%
540
11th to 20thNight
13%7%31%37%10%1
533
21st to endNight
15%5%28%38%13%1
540
May1st to 10thNight
13%5%26%40%14%2
540
11th to 20thNight
20%313%42%18%4
531
21st to endNight
9%322%39%25%3
584
June1st to 10thNight
7%112%46%28%5%
540
11th to 20thNight
7%217%49%23%1
540
21st to endNight
4213%43%35%3
540
July1st to 10thNight
6%28%35%43%5%
525
11th to 20thNight
28%39%46%6%
522
21st to endNight
7%15%33%48%7%
591
August1st to 10thNight
6%18%40%41%5%
537
11th to 20thNight
418%45%36%6%
534
21st to endNight
5%17%43%36%9%
594
September1st to 10thNight
6%110%43%32%8%
540
11th to 20thNight
8%214%45%24%7%
540
21st to endNight
6%217%47%21%6%
540
October1st to 10thNight
10%422%41%19%5%
716
11th to 20thNight
6%6%22%47%15%3
720
21st to endNight
8%8%28%39%13%3
835
November1st to 10thNight
38%28%45%13%2
925
11th to 20thNight
5%14%31%41%8%2
950
21st to endNight
6%9%28%46%10%1
950
December1st to 10thNight
416%29%42%9%
950
11th to 20thNight
412%34%40%9%1
950
21st to endNight
6%16%31%37%9%2
1045
Page generated at 2024-03-24 21:37:03. Version ac07

Copyright © 2024 Attilla Danko.


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