Mayborn Planetarium
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mayborn Planetarium clear sky chart from 2005-11-06 to 2024-01-27.

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
49%
23917
27%
74457
18%
23858
58%
23858
35%
41609

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
35%
949
31%
2458
12%
946
48%
946
39%
1456
January11th to 20thNight
35%
950
28%
2470
10%
950
45%
950
35%
1507
January21st to endNight
32%
977
30%
2617
12%
977
44%
977
32%
1622
February1st to 10thNight
30%
720
28%
2160
12%
720
42%
720
29%
1296
February11th to 20thNight
28%
704
24%
2098
9%
700
40%
700
30%
1248
February21st to endNight
21%
592
28%
1776
8%
592
39%
592
27%
1074
March1st to 10thNight
31%
554
25%
1994
12%
554
45%
554
24%
1166
March11th to 20thNight
32%
540
23%
1980
14%
540
45%
540
25%
1137
March21st to endNight
31%
594
26%
2178
16%
594
46%
594
28%
1183
April1st to 10thNight
30%
540
26%
1980
12%
540
49%
540
28%
1092
April11th to 20thNight
27%
533
22%
1949
14%
533
41%
533
25%
1116
April21st to endNight
30%
540
30%
1624
14%
540
50%
540
33%
952
May1st to 10thNight
34%
540
27%
1620
16%
540
49%
540
34%
940
May11th to 20thNight
41%
531
21%
1594
18%
531
50%
531
33%
960
May21st to endNight
47%
583
24%
1745
16%
582
60%
582
34%
1009
June1st to 10thNight
68%
540
24%
1620
23%
540
75%
540
47%
823
June11th to 20thNight
62%
540
26%
1620
26%
540
69%
540
50%
809
June21st to endNight
70%
540
24%
1620
28%
540
72%
540
41%
886
July1st to 10thNight
72%
525
20%
1575
21%
525
76%
525
38%
884
July11th to 20thNight
82%
522
29%
1566
33%
522
85%
522
57%
731
July21st to endNight
85%
591
28%
1673
31%
558
89%
558
56%
793
August1st to 10thNight
89%
537
35%
1601
38%
534
91%
534
66%
691
August11th to 20thNight
76%
534
29%
1693
32%
534
77%
534
40%
911
August21st to endNight
81%
594
24%
2078
28%
594
83%
594
41%
1043
September1st to 10thNight
74%
540
23%
1980
26%
540
77%
540
34%
1051
September11th to 20thNight
72%
540
22%
1980
25%
540
73%
540
30%
1133
September21st to endNight
73%
540
31%
1980
32%
540
77%
540
41%
963
October1st to 10thNight
74%
540
37%
1980
36%
540
79%
540
46%
890
October11th to 20thNight
54%
674
34%
2114
22%
674
64%
674
40%
1128
October21st to endNight
47%
792
33%
2376
20%
792
55%
792
39%
1304
November1st to 10thNight
54%
740
31%
2220
20%
740
61%
740
39%
1236
November11th to 20thNight
49%
892
29%
2412
16%
892
56%
892
40%
1386
November21st to endNight
39%
950
28%
2470
13%
950
47%
950
32%
1575
December1st to 10thNight
43%
950
32%
2470
15%
950
52%
950
37%
1506
December11th to 20thNight
36%
948
27%
2879
12%
948
45%
948
27%
1806
December21st to endNight
37%
1041
18%
4307
12%
1026
46%
1026
26%
2302

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
11%5%2443445%7%51%
75028
Night
11%42442345%7%55%
75046
TransparencyDay
33%6%10%21%21%9%
74753
Night
30%5%11%21%21%12%
74841
SeeingDay
12%7%22%29%23%7%
13862
Night
13%6%27%36%16%1
23925

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
13%423324446%55%
1707
11th to 20thDay
18%5%23223346%52%
1710
21st to endDay
15%5%23424435%53%
1899
February1st to 10thDay
18%6%25%41333451%
1800
11th to 20thDay
16%7%35%423445%48%
1749
21st to endDay
19%6%23323345%50%
1480
March1st to 10thDay
18%6%26%43435%5%43%
1963
11th to 20thDay
15%5%35%434445%47%
1980
21st to endDay
13%6%35%424345%52%
2178
April1st to 10thDay
13%7%45%5%2445%6%45%
1980
11th to 20thDay
15%6%35%6%335%5%6%45%
1958
21st to endDay
13%435%5%2445%6%50%
2330
May1st to 10thDay
12%5%36%5%35%5%5%6%45%
2340
11th to 20thDay
12%7%36%5%35%45%8%42%
2302
21st to endDay
13%6%37%6%46%7%6%8%36%
2531
June1st to 10thDay
5%3135%45%47%9%54%
2340
11th to 20thDay
5%4245%35%5%6%9%54%
2340
21st to endDay
7%4246%45%6%6%9%47%
2340
July1st to 10thDay
9%435%5%5%5%7%7%10%41%
2340
11th to 20thDay
4213335%5%7%10%58%
2340
21st to endDay
3323435%5%6%10%57%
2546
August1st to 10thDay
221233345%8%68%
2328
11th to 20thDay
7%4135%45%5%6%9%51%
2203
21st to endDay
5%314435%7%7%9%50%
2276
September1st to 10thDay
10%4246%45%45%8%48%
1980
11th to 20thDay
11%5%35%5%35%45%8%46%
1980
21st to endDay
7%315%5%3445%8%54%
1980
October1st to 10thDay
6%41442445%6%59%
1980
11th to 20thDay
11%5%23423246%59%
1828
21st to endDay
13%5%1432323461%
1980
November1st to 10thDay
14%5%25%324345%53%
1858
11th to 20thDay
9%5%25%434446%56%
1766
21st to endDay
17%6%34423345%50%
1710
December1st to 10thDay
15%5%24423445%52%
1710
11th to 20thDay
15%7%35%434445%46%
2161
21st to endDay
15%6%24322345%55%
3135
January1st to 10thNight
15%413322346%57%
2458
11th to 20thNight
15%5%23323345%55%
2470
21st to endNight
15%5%35%423345%52%
2617
February1st to 10thNight
15%6%34423335%53%
2160
11th to 20thNight
18%5%24323335%52%
2098
21st to endNight
18%5%24323346%50%
1776
March1st to 10thNight
15%5%25%5%2345%7%46%
1994
11th to 20thNight
14%5%25%42445%6%48%
1980
21st to endNight
12%42442335%7%54%
2178
April1st to 10thNight
9%5%244245%5%6%52%
1980
11th to 20thNight
13%5%35%5%345%46%49%
1949
21st to endNight
12%5%3433435%7%52%
1624
May1st to 10thNight
10%4335%245%6%8%51%
1620
11th to 20thNight
11%5%2443446%10%47%
1593
21st to endNight
10%4245%3446%10%49%
1745
June1st to 10thNight
33133245%6%9%62%
1620
11th to 20thNight
321342436%10%61%
1620
21st to endNight
5%4135%25%5%6%9%55%
1620
July1st to 10thNight
5%3135%445%6%11%53%
1620
11th to 20thNight
211222346%9%67%
1620
21st to endNight
11133245%7%11%62%
1772
August1st to 10thNight
111111235%9%75%
1611
11th to 20thNight
5%425%423448%57%
1693
21st to endNight
5%2144345%7%10%55%
2078
September1st to 10thNight
8%3244345%6%8%53%
1980
11th to 20thNight
11%5%2443446%8%49%
1980
21st to endNight
8%3223235%6%8%59%
1980
October1st to 10thNight
6%312323346%66%
1980
11th to 20thNight
12%313323446%59%
2114
21st to endNight
14%42432233461%
2376
November1st to 10thNight
11%5%23323446%58%
2220
11th to 20thNight
6%6%24433445%59%
2412
21st to endNight
16%5%34423446%49%
2470
December1st to 10thNight
12%5%2433335%6%54%
2470
11th to 20thNight
14%7%35%434346%48%
3036
21st to endNight
17%7%1331223357%
4532

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
32%36%19%27%13%
1708
11th to 20thDay
35%46%18%25%13%
1710
21st to endDay
35%37%14%26%15%
1899
February1st to 10thDay
39%37%13%23%15%
1800
11th to 20thDay
40%36%18%21%12%
1759
21st to endDay
39%35%16%20%17%
1480
March1st to 10thDay
43%48%13%21%10%
1963
11th to 20thDay
39%6%8%13%21%13%
1980
21st to endDay
35%5%10%17%22%11%
2178
April1st to 10thDay
40%5%8%18%17%12%
1980
11th to 20thDay
40%48%17%18%12%
1958
21st to endDay
35%6%8%19%24%9%
2330
May1st to 10thDay
39%6%10%18%19%8%
2340
11th to 20thDay
41%6%11%20%18%4
2306
21st to endDay
44%8%12%20%15%2
2531
June1st to 10thDay
26%7%15%26%21%5%
2340
11th to 20thDay
27%6%13%29%18%6%
2340
21st to endDay
31%8%13%23%21%4
2340
July1st to 10thDay
35%10%16%26%11%2
2276
11th to 20thDay
19%8%17%28%24%4
2271
21st to endDay
20%7%19%36%17%1
2405
August1st to 10thDay
14%6%17%37%25%2
2314
11th to 20thDay
27%9%15%30%15%4
2203
21st to endDay
27%9%15%28%17%4
2276
September1st to 10thDay
33%7%11%22%18%9%
1980
11th to 20thDay
37%7%11%20%19%5%
1980
21st to endDay
28%5%10%22%22%13%
1980
October1st to 10thDay
25%5%11%23%22%14%
1980
11th to 20thDay
29%47%17%25%19%
1828
21st to endDay
29%35%17%27%20%
1980
November1st to 10thDay
34%5%9%20%23%10%
1858
11th to 20thDay
31%49%18%24%15%
1766
21st to endDay
39%45%18%21%14%
1710
December1st to 10thDay
36%49%20%22%10%
1710
11th to 20thDay
40%5%7%12%23%13%
2159
21st to endDay
33%36%15%28%15%
3135
January1st to 10thNight
31%36%19%25%17%
2458
11th to 20thNight
34%37%17%25%15%
2470
21st to endNight
36%45%15%22%19%
2617
February1st to 10thNight
37%36%13%22%18%
2160
11th to 20thNight
37%36%17%22%15%
2098
21st to endNight
38%46%15%18%19%
1776
March1st to 10thNight
38%5%10%12%24%11%
1994
11th to 20thNight
37%5%10%13%22%13%
1980
21st to endNight
32%6%10%19%22%12%
2178
April1st to 10thNight
33%5%9%21%18%15%
1980
11th to 20thNight
37%411%15%19%15%
1949
21st to endNight
33%5%10%20%23%9%
1624
May1st to 10thNight
30%7%12%22%21%8%
1620
11th to 20thNight
32%7%14%25%18%4
1594
21st to endNight
31%7%15%29%16%2
1746
June1st to 10thNight
19%7%16%31%22%4
1620
11th to 20thNight
19%6%15%33%21%7%
1620
21st to endNight
24%8%14%28%22%5%
1620
July1st to 10thNight
26%9%19%31%14%1
1575
11th to 20thNight
13%6%20%33%25%3
1566
21st to endNight
13%8%25%38%15%1
1673
August1st to 10thNight
8%6%18%40%25%3
1601
11th to 20thNight
25%6%16%31%16%5%
1693
21st to endNight
22%8%20%30%16%5%
2078
September1st to 10thNight
29%6%14%23%18%10%
1980
11th to 20thNight
33%7%15%21%17%7%
1980
21st to endNight
23%6%12%25%20%15%
1980
October1st to 10thNight
20%311%27%21%17%
1980
11th to 20thNight
28%39%16%22%22%
2114
21st to endNight
29%37%16%23%23%
2376
November1st to 10thNight
29%48%20%25%14%
2220
11th to 20thNight
28%5%8%19%24%16%
2412
21st to endNight
37%47%15%22%15%
2470
December1st to 10thNight
32%5%8%21%21%12%
2470
11th to 20thNight
39%36%12%23%17%
3037
21st to endNight
34%25%14%28%16%
4532

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
20%13%34%26%6%1
270
11th to 20thDay
23%14%33%20%7%1
270
21st to endDay
18%15%39%21%7%
282
February1st to 10thDay
23%14%35%23%4
240
11th to 20thDay
24%15%39%19%3
240
21st to endDay
28%19%35%16%3
198
March1st to 10thDay
21%19%35%23%3
240
11th to 20thDay
21%17%34%22%5%1
240
21st to endDay
17%16%39%22%6%
264
April1st to 10thDay
20%16%42%18%4
240
11th to 20thDay
19%14%36%22%7%1
236
21st to endDay
15%15%38%23%8%1
590
May1st to 10thDay
13%11%37%29%10%
603
11th to 20thDay
16%5%30%31%14%3
625
21st to endDay
16%5%23%35%17%4
679
June1st to 10thDay
6%216%39%27%10%
630
11th to 20thDay
6%117%47%25%5%
630
21st to endDay
6%213%36%33%9%
630
July1st to 10thDay
9%110%33%34%14%
621
11th to 20thDay
25%35%45%13%
618
21st to endDay
2435%45%14%
684
August1st to 10thDay
215%33%45%14%
626
11th to 20thDay
6%2433%40%15%
517
21st to endDay
6%15%23%40%26%
395
September1st to 10thDay
9%1221%42%25%
270
11th to 20thDay
6%7%20%46%20%
270
21st to endDay
13%25%29%36%15%
270
October1st to 10thDay
4313%38%32%11%
270
11th to 20thDay
12%5%25%29%25%5%
270
21st to endDay
26%10%22%21%18%4
297
November1st to 10thDay
19%7%31%27%12%4
270
11th to 20thDay
16%9%28%30%13%4
270
21st to endDay
21%13%31%23%10%1
270
December1st to 10thDay
18%7%31%26%12%5%
270
11th to 20thDay
20%13%39%21%7%
270
21st to endDay
20%10%38%22%8%1
297
January1st to 10thNight
17%8%36%31%8%
950
11th to 20thNight
19%10%32%31%8%
950
21st to endNight
17%11%35%29%7%
977
February1st to 10thNight
19%12%35%30%5%
720
11th to 20thNight
21%12%37%27%3
704
21st to endNight
22%12%42%22%3
592
March1st to 10thNight
18%11%38%28%5%
554
11th to 20thNight
16%9%38%30%6%
540
21st to endNight
12%12%42%31%3
594
April1st to 10thNight
11%9%48%30%3
540
11th to 20thNight
15%10%42%26%6%
533
21st to endNight
13%9%45%24%9%
540
May1st to 10thNight
12%9%43%31%6%
540
11th to 20thNight
13%5%36%33%12%1
531
21st to endNight
11%333%37%15%1
584
June1st to 10thNight
3221%47%24%3
540
11th to 20thNight
3226%51%17%1
540
21st to endNight
4117%47%27%3
540
July1st to 10thNight
5%112%46%31%4
525
11th to 20thNight
39%53%32%2
522
21st to endNight
217%53%34%3
591
August1st to 10thNight
15%54%35%4
537
11th to 20thNight
7%6%47%35%5%
534
21st to endNight
5%1444%40%6%
594
September1st to 10thNight
9%18%41%35%5%
540
11th to 20thNight
13%15%39%38%4
540
21st to endNight
9%112%39%37%3
540
October1st to 10thNight
7%12%49%26%4
540
11th to 20thNight
12%423%40%19%2
674
21st to endNight
14%8%27%31%18%1
792
November1st to 10thNight
14%426%40%16%1
740
11th to 20thNight
9%8%29%38%15%1
892
21st to endNight
19%9%29%31%12%1
950
December1st to 10thNight
15%8%31%36%10%1
950
11th to 20thNight
20%8%30%35%7%
950
21st to endNight
20%8%33%32%7%
1045
Page generated at 2024-01-24 08:37:30. Version ac07

Copyright 2024 Attilla Danko


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