Oklahoma Christian University Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oklahoma Christian University Observatory clear sky chart from 2005-11-06 to 2024-03-06.

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
41%
24466
27%
79754
16%
24358
53%
24358
34%
43293

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
31%
943
28%
4009
11%
926
44%
926
23%
2292
January11th to 20thNight
30%
950
29%
3983
10%
930
43%
930
29%
1795
January21st to endNight
33%
1036
23%
4461
11%
1023
48%
1023
24%
2561
February1st to 10thNight
25%
890
24%
2410
8%
890
36%
890
30%
1501
February11th to 20thNight
26%
744
25%
2218
8%
740
39%
740
31%
1268
February21st to endNight
25%
628
28%
1884
9%
628
40%
628
27%
1123
March1st to 10thNight
30%
600
27%
2084
15%
600
45%
600
28%
1158
March11th to 20thNight
28%
540
25%
1980
13%
540
43%
540
27%
1098
March21st to endNight
25%
594
21%
2178
11%
594
40%
594
23%
1253
April1st to 10thNight
25%
540
26%
1980
12%
540
46%
540
30%
1005
April11th to 20thNight
22%
533
24%
1775
11%
533
40%
533
28%
976
April21st to endNight
32%
540
27%
1620
15%
540
50%
540
32%
935
May1st to 10thNight
27%
540
25%
1620
12%
540
45%
540
32%
963
May11th to 20thNight
37%
531
22%
1594
18%
531
46%
531
32%
959
May21st to endNight
46%
584
23%
1745
17%
582
58%
582
37%
988
June1st to 10thNight
60%
540
23%
1620
19%
540
67%
540
46%
827
June11th to 20thNight
51%
540
23%
1620
17%
540
61%
540
44%
859
June21st to endNight
62%
540
29%
1620
23%
540
69%
540
56%
766
July1st to 10thNight
71%
525
20%
1575
19%
525
74%
525
42%
860
July11th to 20thNight
77%
522
28%
1566
29%
522
81%
522
53%
758
July21st to endNight
79%
591
30%
1673
34%
558
82%
558
51%
825
August1st to 10thNight
74%
537
28%
1601
29%
534
79%
534
49%
806
August11th to 20thNight
67%
534
30%
1600
30%
534
73%
534
41%
873
August21st to endNight
78%
594
28%
1940
32%
594
81%
594
50%
904
September1st to 10thNight
64%
540
27%
1980
28%
540
70%
540
40%
952
September11th to 20thNight
56%
540
28%
1980
25%
540
65%
540
32%
1079
September21st to endNight
58%
540
34%
1980
28%
540
69%
540
42%
920
October1st to 10thNight
51%
558
34%
1998
25%
558
62%
558
39%
968
October11th to 20thNight
39%
720
34%
2160
15%
720
52%
720
42%
1133
October21st to endNight
38%
792
32%
2376
14%
792
52%
792
38%
1282
November1st to 10thNight
38%
820
33%
2300
13%
820
53%
820
47%
1189
November11th to 20thNight
36%
950
30%
2470
12%
950
48%
950
42%
1398
November21st to endNight
34%
950
31%
2470
13%
950
45%
950
37%
1473
December1st to 10thNight
36%
950
32%
2470
12%
950
49%
950
40%
1421
December11th to 20thNight
28%
949
31%
2860
10%
948
41%
948
30%
1693
December21st to endNight
31%
1041
20%
4354
11%
1026
46%
1026
23%
2432

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%5%25%43445%7%52%
78961
Night
9%5%2432345%7%56%
80622
TransparencyDay
32%5%11%25%22%6%
78686
Night
29%5%10%24%25%8%
80417
SeeingDay
12%10%28%30%17%4
14394
Night
11%10%33%33%11%1
24487

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
8%8%47%5%3445%6%47%
2847
11th to 20thDay
8%5%24323346%59%
2850
21st to endDay
16%9%45%312335%48%
3135
February1st to 10thDay
10%11%36%423445%48%
1786
11th to 20thDay
10%6%36%433445%51%
1849
21st to endDay
11%8%45%322346%51%
1570
March1st to 10thDay
10%6%345%34446%51%
1991
11th to 20thDay
15%8%34423445%48%
1980
21st to endDay
12%8%25%6%2445%7%44%
2178
April1st to 10thDay
8%425%5%345%5%7%53%
1980
11th to 20thDay
13%5%35%5%345%5%6%47%
2131
21st to endDay
15%6%25%42445%6%47%
2340
May1st to 10thDay
14%5%36%43445%7%45%
2340
11th to 20thDay
12%6%3443445%6%48%
2302
21st to endDay
9%6%26%6%5%5%6%6%8%41%
2531
June1st to 10thDay
6%4244345%6%10%51%
2340
11th to 20thDay
6%3144345%6%10%54%
2340
21st to endDay
43134245%6%8%60%
2340
July1st to 10thDay
6%3245%46%6%7%10%48%
2340
11th to 20thDay
42134245%6%10%58%
2340
21st to endDay
5%424435%5%7%11%52%
2546
August1st to 10thDay
4425%5%345%6%9%54%
2328
11th to 20thDay
7%424435%6%7%10%47%
2301
21st to endDay
4214435%5%7%8%56%
2410
September1st to 10thDay
10%414423447%56%
1980
11th to 20thDay
11%5%25%5%35%447%48%
1980
21st to endDay
8%31433445%6%59%
1980
October1st to 10thDay
8%423423345%61%
1944
11th to 20thDay
10%312322235%67%
1800
21st to endDay
12%5%2432333458%
1980
November1st to 10thDay
8%423323346%63%
1776
11th to 20thDay
7%5%13312335%66%
1710
21st to endDay
11%6%24323346%58%
1710
December1st to 10thDay
9%7%25%323347%55%
1710
11th to 20thDay
12%5%25%5%3445%5%51%
2161
21st to endDay
9%9%47%5%35%45%6%44%
3135
January1st to 10thNight
10%9%35%424345%51%
4108
11th to 20thNight
6%42342335%7%59%
4120
21st to endNight
17%8%34322245%52%
4532
February1st to 10thNight
13%8%35%423335%51%
2410
11th to 20thNight
12%6%35%333345%54%
2218
21st to endNight
11%7%44333445%53%
1884
March1st to 10thNight
8%5%344345%46%54%
2084
11th to 20thNight
16%6%23323335%54%
1980
21st to endNight
12%6%25%434446%50%
2178
April1st to 10thNight
10%413424447%57%
1980
11th to 20thNight
13%424423448%52%
1775
21st to endNight
12%6%23333347%54%
1620
May1st to 10thNight
11%5%2442445%8%50%
1620
11th to 20thNight
10%5%24335%5%6%8%49%
1593
21st to endNight
6%425%3345%7%10%51%
1745
June1st to 10thNight
6%31232346%9%60%
1620
11th to 20thNight
43143245%6%10%57%
1620
21st to endNight
421222345%10%66%
1620
July1st to 10thNight
4314435%47%11%53%
1620
11th to 20thNight
22133245%6%9%62%
1620
21st to endNight
42123325%6%11%61%
1772
August1st to 10thNight
1213425%6%8%10%57%
1611
11th to 20thNight
5%314435%6%6%9%54%
1600
21st to endNight
22134235%6%11%60%
1940
September1st to 10thNight
8%413323446%61%
1980
11th to 20thNight
10%5%25%424346%54%
1980
21st to endNight
6%42432335%6%63%
1980
October1st to 10thNight
7%32343345%5%61%
1998
11th to 20thNight
9%42332233464%
2160
21st to endNight
11%42331334462%
2376
November1st to 10thNight
7%412223345%66%
2300
11th to 20thNight
7%425%423335%63%
2470
21st to endNight
10%5%34323346%56%
2470
December1st to 10thNight
10%5%2332335%7%58%
2470
11th to 20thNight
9%6%345%34445%55%
3036
21st to endNight
13%7%25%423346%50%
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
38%48%22%23%4
2848
11th to 20thDay
26%312%26%27%5%
2850
21st to endDay
41%36%23%23%4
3135
February1st to 10thDay
40%39%22%21%5%
1786
11th to 20thDay
36%38%26%21%5%
1859
21st to endDay
36%46%20%25%9%
1570
March1st to 10thDay
36%37%21%21%12%
1991
11th to 20thDay
40%49%22%19%7%
1980
21st to endDay
39%6%11%23%17%4
2178
April1st to 10thDay
31%6%11%26%19%7%
1980
11th to 20thDay
37%6%10%21%18%7%
2131
21st to endDay
38%6%9%25%19%3
2340
May1st to 10thDay
38%6%11%21%20%3
2340
11th to 20thDay
37%6%13%28%15%1
2306
21st to endDay
40%8%14%24%13%2
2531
June1st to 10thDay
27%9%18%27%15%4
2340
11th to 20thDay
26%7%14%29%20%4
2340
21st to endDay
22%6%14%27%24%6%
2340
July1st to 10thDay
28%9%18%27%16%2
2276
11th to 20thDay
20%6%14%29%27%5%
2271
21st to endDay
25%7%14%32%21%1
2405
August1st to 10thDay
25%7%14%29%18%7%
2314
11th to 20thDay
31%7%15%26%19%2
2301
21st to endDay
23%7%14%30%20%6%
2410
September1st to 10thDay
28%410%25%23%10%
1980
11th to 20thDay
35%6%9%22%22%6%
1980
21st to endDay
25%6%8%24%31%6%
1980
October1st to 10thDay
26%5%10%23%27%8%
1944
11th to 20thDay
23%38%21%34%12%
1800
21st to endDay
32%38%24%22%11%
1980
November1st to 10thDay
24%48%26%28%10%
1776
11th to 20thDay
23%28%29%27%10%
1710
21st to endDay
29%37%25%25%10%
1710
December1st to 10thDay
32%410%27%24%3
1710
11th to 20thDay
36%38%20%27%6%
2159
21st to endDay
41%48%22%22%3
3135
January1st to 10thNight
36%5%6%23%25%5%
4108
11th to 20thNight
24%5%16%23%27%6%
4120
21st to endNight
38%37%20%26%6%
4532
February1st to 10thNight
37%48%22%23%6%
2410
11th to 20thNight
33%48%26%22%8%
2218
21st to endNight
35%45%19%24%13%
1884
March1st to 10thNight
33%47%20%22%14%
2084
11th to 20thNight
35%39%24%21%9%
1980
21st to endNight
36%6%12%23%18%5%
2178
April1st to 10thNight
27%5%10%23%23%12%
1980
11th to 20thNight
31%5%11%25%18%10%
1775
21st to endNight
32%410%26%23%4
1620
May1st to 10thNight
33%6%11%23%21%5%
1620
11th to 20thNight
33%7%13%26%18%3
1594
21st to endNight
28%7%18%29%16%3
1746
June1st to 10thNight
20%7%21%30%19%3
1620
11th to 20thNight
22%6%15%29%21%6%
1620
21st to endNight
15%6%12%32%26%9%
1620
July1st to 10thNight
24%8%16%31%19%3
1575
11th to 20thNight
16%7%11%28%31%7%
1566
21st to endNight
18%6%13%33%27%3
1673
August1st to 10thNight
19%7%15%29%24%6%
1601
11th to 20thNight
25%6%13%24%26%6%
1600
21st to endNight
17%6%15%29%25%8%
1940
September1st to 10thNight
25%39%26%25%12%
1980
11th to 20thNight
32%5%9%19%26%9%
1980
21st to endNight
22%49%25%31%9%
1980
October1st to 10thNight
24%412%21%26%12%
1998
11th to 20thNight
25%36%17%33%15%
2160
21st to endNight
27%37%23%27%13%
2376
November1st to 10thNight
22%39%23%31%13%
2300
11th to 20thNight
26%37%24%30%10%
2470
21st to endNight
31%36%21%28%11%
2470
December1st to 10thNight
28%410%27%25%7%
2470
11th to 20thNight
34%37%22%28%7%
3037
21st to endNight
35%48%23%22%8%
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
16%17%38%21%8%
270
11th to 20thDay
20%20%39%19%21
270
21st to endDay
14%19%41%21%41
297
February1st to 10thDay
20%19%41%17%4
270
11th to 20thDay
17%23%43%15%2
270
21st to endDay
24%25%37%12%2
225
March1st to 10thDay
16%23%38%18%4
255
11th to 20thDay
26%23%31%17%3
240
21st to endDay
20%23%38%15%4
264
April1st to 10thDay
17%20%38%21%5%
240
11th to 20thDay
19%19%40%19%3
409
21st to endDay
21%17%33%22%7%1
600
May1st to 10thDay
13%15%43%23%5%1
603
11th to 20thDay
16%11%32%26%14%2
625
21st to endDay
10%10%31%27%17%4
679
June1st to 10thDay
7%5%21%40%22%5%
630
11th to 20thDay
6%231%42%16%3
630
21st to endDay
3228%42%20%4
630
July1st to 10thDay
5%212%38%34%9%
621
11th to 20thDay
3114%43%33%6%
618
21st to endDay
7%16%39%36%10%
684
August1st to 10thDay
6%112%43%33%5%
626
11th to 20thDay
8%215%38%29%7%
615
21st to endDay
5%212%38%36%8%
529
September1st to 10thDay
8%310%35%33%10%
270
11th to 20thDay
7%314%36%31%8%
270
21st to endDay
10%5%17%40%21%6%
270
October1st to 10thDay
9%7%29%33%16%7%
270
11th to 20thDay
11%14%36%29%9%1
270
21st to endDay
22%11%33%23%8%3
297
November1st to 10thDay
13%15%36%27%7%2
270
11th to 20thDay
16%14%37%23%9%2
270
21st to endDay
17%21%36%21%4
270
December1st to 10thDay
13%16%41%21%9%
270
11th to 20thDay
19%16%39%17%9%
270
21st to endDay
18%23%36%20%3
297
January1st to 10thNight
11%13%40%29%6%1
950
11th to 20thNight
14%14%39%29%5%
950
21st to endNight
13%14%38%31%5%
1045
February1st to 10thNight
17%15%39%25%4
890
11th to 20thNight
16%16%40%24%3
744
21st to endNight
17%16%40%25%3
628
March1st to 10thNight
11%14%41%31%3
600
11th to 20thNight
20%11%38%27%3
540
21st to endNight
16%16%40%23%5%
594
April1st to 10thNight
12%17%43%22%6%
540
11th to 20thNight
16%15%44%22%4
533
21st to endNight
16%14%37%27%6%
540
May1st to 10thNight
10%11%47%25%7%
540
11th to 20thNight
13%8%38%25%15%1
531
21st to endNight
8%7%34%33%16%1
584
June1st to 10thNight
7%424%45%18%3
540
11th to 20thNight
5%435%44%11%1
540
21st to endNight
3230%45%19%2
540
July1st to 10thNight
6%116%46%28%3
525
11th to 20thNight
3115%53%26%2
522
21st to endNight
5%110%55%27%2
591
August1st to 10thNight
2116%52%26%3
537
11th to 20thNight
7%117%46%28%1
534
21st to endNight
3112%46%35%4
594
September1st to 10thNight
9%219%44%23%2
540
11th to 20thNight
12%222%38%23%3
540
21st to endNight
8%425%43%16%4
540
October1st to 10thNight
9%432%33%19%3
558
11th to 20thNight
13%8%38%31%10%1
720
21st to endNight
14%13%32%29%10%1
792
November1st to 10thNight
10%9%40%29%11%1
820
11th to 20thNight
10%13%38%30%9%
950
21st to endNight
14%14%35%30%7%
950
December1st to 10thNight
13%11%36%31%7%
950
11th to 20thNight
16%12%39%26%6%
950
21st to endNight
15%14%37%29%5%
1045
Page generated at 2024-03-03 05:28:57. Version ac07

Copyright © 2024 Attilla Danko.


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