Bryan College
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bryan College clear sky chart from 2005-11-06 to 2024-03-23.

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
48%
23954
22%
80020
16%
23853
55%
23853
25%
49576

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
25%
756
22%
4003
10%
737
39%
737
13%
2404
January11th to 20thNight
27%
756
25%
3958
11%
740
38%
740
12%
2417
January21st to endNight
29%
829
16%
4339
13%
814
42%
814
13%
2858
February1st to 10thNight
31%
760
22%
2280
12%
760
41%
760
25%
1478
February11th to 20thNight
23%
743
18%
2218
8%
739
32%
739
19%
1519
February21st to endNight
21%
628
20%
1884
9%
628
30%
628
19%
1320
March1st to 10thNight
33%
760
22%
2275
12%
760
43%
760
26%
1454
March11th to 20thNight
32%
760
21%
2090
11%
760
39%
760
26%
1389
March21st to endNight
36%
801
19%
2201
11%
801
43%
801
26%
1472
April1st to 10thNight
43%
594
27%
1854
19%
594
54%
594
34%
1049
April11th to 20thNight
42%
533
28%
1775
18%
533
56%
533
31%
1006
April21st to endNight
52%
540
26%
1670
18%
540
60%
540
32%
974
May1st to 10thNight
49%
540
22%
1620
12%
540
57%
540
32%
971
May11th to 20thNight
55%
531
19%
1593
14%
531
60%
531
28%
1002
May21st to endNight
66%
582
19%
1744
14%
582
68%
582
31%
1084
June1st to 10thNight
63%
540
18%
1620
15%
540
66%
540
28%
1028
June11th to 20thNight
77%
540
19%
1620
16%
540
79%
540
45%
862
June21st to endNight
74%
540
18%
1620
14%
540
76%
540
33%
968
July1st to 10thNight
68%
525
13%
1575
11%
525
69%
525
27%
1021
July11th to 20thNight
69%
522
16%
1566
14%
522
71%
522
33%
944
July21st to endNight
71%
591
17%
1672
16%
558
73%
558
31%
1045
August1st to 10thNight
72%
537
18%
1600
17%
534
74%
534
30%
982
August11th to 20thNight
67%
534
16%
1746
18%
534
68%
534
28%
1079
August21st to endNight
71%
594
19%
1980
23%
594
71%
594
27%
1230
September1st to 10thNight
67%
640
21%
1900
20%
640
68%
640
30%
1170
September11th to 20thNight
62%
720
22%
1980
18%
720
64%
720
30%
1288
September21st to endNight
61%
720
29%
1980
21%
720
67%
720
36%
1196
October1st to 10thNight
61%
720
33%
1980
28%
720
65%
720
41%
1132
October11th to 20thNight
51%
720
30%
2056
22%
720
60%
720
36%
1214
October21st to endNight
53%
792
32%
2456
28%
792
62%
792
34%
1416
November1st to 10thNight
52%
740
29%
2406
26%
740
60%
740
33%
1317
November11th to 20thNight
42%
760
29%
2470
20%
760
55%
760
32%
1414
November21st to endNight
41%
760
25%
2470
19%
760
52%
760
26%
1500
December1st to 10thNight
33%
760
21%
2470
15%
760
43%
760
20%
1661
December11th to 20thNight
39%
759
26%
2911
19%
758
48%
758
22%
1756
December21st to endNight
32%
827
13%
4438
12%
817
40%
817
11%
2956

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%6%36%5%35%5%6%8%39%
79114
Night
14%6%35%5%35%5%5%7%43%
80786
TransparencyDay
43%411%22%16%3
78837
Night
41%410%23%18%4
80582
SeeingDay
17%8%20%24%21%11%
13830
Night
16%7%21%32%20%4
23981

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
17%11%36%5%345%6%6%35%
2836
11th to 20thDay
20%7%47%6%34335%39%
2840
21st to endDay
23%10%35%423447%36%
3249
February1st to 10thDay
19%9%36%5%3445%6%36%
1900
11th to 20thDay
22%8%35%5%3446%5%36%
1848
21st to endDay
20%8%36%435%45%7%36%
1570
March1st to 10thDay
17%6%25%435%5%5%6%41%
1905
11th to 20thDay
20%6%46%5%2445%6%37%
2090
21st to endDay
16%6%46%5%36%5%6%7%36%
2200
April1st to 10thDay
12%435%5%35%6%6%7%44%
2120
11th to 20thDay
14%6%26%43445%6%45%
2134
21st to endDay
13%5%25%6%445%6%8%43%
2290
May1st to 10thDay
12%5%26%5%35%5%5%8%45%
2340
11th to 20thDay
12%7%37%5%35%6%6%8%38%
2301
21st to endDay
10%5%25%6%46%6%7%10%40%
2531
June1st to 10thDay
8%6%26%6%46%6%7%9%39%
2340
11th to 20thDay
5%3246%46%7%9%12%43%
2340
21st to endDay
7%5%346%46%7%7%11%39%
2340
July1st to 10thDay
8%6%36%7%6%9%7%8%10%31%
2340
11th to 20thDay
11%436%7%48%7%8%11%30%
2340
21st to endDay
7%5%37%8%5%8%8%8%10%31%
2547
August1st to 10thDay
9%5%26%8%5%8%8%10%10%30%
2327
11th to 20thDay
10%6%37%7%5%7%7%8%8%33%
2151
21st to endDay
12%6%25%6%47%6%8%9%33%
2376
September1st to 10thDay
11%5%35%6%45%7%6%8%39%
2040
11th to 20thDay
14%425%6%36%6%6%8%40%
1980
21st to endDay
13%424435%447%49%
1980
October1st to 10thDay
12%5%24424445%54%
1980
11th to 20thDay
13%5%13424346%54%
1903
21st to endDay
14%42442445%7%49%
1897
November1st to 10thDay
11%425%5%3443456%
1672
11th to 20thDay
14%425%5%2445%6%48%
1710
21st to endDay
16%6%25%424446%46%
1710
December1st to 10thDay
22%7%36%6%34445%36%
1710
11th to 20thDay
14%7%36%7%45%5%5%5%39%
2153
21st to endDay
19%8%37%5%3445%7%33%
3124
January1st to 10thNight
18%9%36%43445%6%39%
4109
11th to 20thNight
19%8%45%5%24446%38%
4120
21st to endNight
22%11%26%5%24445%35%
4404
February1st to 10thNight
16%6%35%5%35%45%6%41%
2280
11th to 20thNight
21%6%46%5%4444437%
2218
21st to endNight
23%8%46%43445%5%35%
1884
March1st to 10thNight
16%7%25%43445%6%43%
2275
11th to 20thNight
15%6%45%6%45%447%41%
2090
21st to endNight
13%7%36%6%45%45%7%41%
2201
April1st to 10thNight
12%42443346%7%51%
1854
11th to 20thNight
13%5%2442345%7%51%
1775
21st to endNight
11%425%5%345%5%8%49%
1670
May1st to 10thNight
10%5%25%5%346%6%7%47%
1620
11th to 20thNight
11%5%25%5%46%5%6%7%44%
1592
21st to endNight
8%6%245%36%5%7%9%44%
1744
June1st to 10thNight
7%5%36%5%47%6%6%8%43%
1620
11th to 20thNight
5%3133346%8%14%51%
1620
21st to endNight
5%325%5%46%7%6%12%45%
1620
July1st to 10thNight
10%6%35%6%46%6%9%11%35%
1620
11th to 20thNight
8%5%35%5%45%6%7%12%42%
1620
21st to endNight
6%6%25%5%5%6%7%8%13%37%
1771
August1st to 10thNight
6%425%6%5%5%5%9%11%41%
1611
11th to 20thNight
9%5%35%7%445%6%9%42%
1746
21st to endNight
10%425%6%37%6%7%11%38%
1980
September1st to 10thNight
9%5%36%5%35%5%6%9%43%
1900
11th to 20thNight
13%6%25%5%35%5%5%7%44%
1980
21st to endNight
10%5%25%42445%6%52%
1980
October1st to 10thNight
11%413423336%59%
1980
11th to 20thNight
13%42443445%6%52%
2056
21st to endNight
14%5%24333346%53%
2456
November1st to 10thNight
12%5%25%423346%54%
2406
11th to 20thNight
12%5%35%433347%51%
2470
21st to endNight
17%6%2442445%7%44%
2470
December1st to 10thNight
20%8%35%5%35%446%36%
2470
11th to 20thNight
16%6%26%434446%44%
3042
21st to endNight
20%7%36%6%46%6%6%7%29%
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
50%26%22%18%2
2837
11th to 20thDay
51%26%19%20%1
2840
21st to endDay
51%27%23%16%1
3249
February1st to 10thDay
50%37%20%17%3
1900
11th to 20thDay
51%37%20%16%4
1858
21st to endDay
50%29%16%17%6%
1570
March1st to 10thDay
44%310%19%18%6%
1905
11th to 20thDay
49%39%20%15%4
2090
21st to endDay
47%312%24%13%1
2200
April1st to 10thDay
38%411%25%19%3
2120
11th to 20thDay
40%28%20%24%5%
2134
21st to endDay
40%310%28%16%2
2290
May1st to 10thDay
39%412%28%14%3
2340
11th to 20thDay
44%6%15%22%13%1
2305
21st to endDay
39%6%15%24%15%2
2531
June1st to 10thDay
39%5%17%23%14%2
2340
11th to 20thDay
31%6%21%25%14%2
2340
21st to endDay
37%8%18%20%14%4
2340
July1st to 10thDay
44%7%16%18%12%3
2275
11th to 20thDay
43%7%20%17%10%4
2271
21st to endDay
43%7%18%23%9%1
2405
August1st to 10thDay
43%8%18%21%8%1
2314
11th to 20thDay
44%7%16%19%12%2
2151
21st to endDay
44%6%16%19%13%3
2376
September1st to 10thDay
41%5%13%19%16%5%
2040
11th to 20thDay
41%5%11%21%19%3
1980
21st to endDay
35%311%23%21%7%
1980
October1st to 10thDay
33%38%23%25%7%
1980
11th to 20thDay
33%28%24%25%8%
1903
21st to endDay
36%27%24%27%4
1897
November1st to 10thDay
33%38%23%27%6%
1672
11th to 20thDay
37%26%25%24%5%
1710
21st to endDay
41%27%26%19%4
1710
December1st to 10thDay
51%36%23%14%3
1710
11th to 20thDay
48%38%22%18%3
2150
21st to endDay
52%39%23%11%2
3124
January1st to 10thNight
48%25%26%18%2
4109
11th to 20thNight
49%26%20%18%5%
4120
21st to endNight
54%26%20%17%1
4404
February1st to 10thNight
45%210%23%17%3
2280
11th to 20thNight
51%27%20%15%5%
2219
21st to endNight
52%36%17%17%5%
1884
March1st to 10thNight
42%39%19%20%7%
2275
11th to 20thNight
45%39%22%17%4
2090
21st to endNight
45%39%25%15%2
2201
April1st to 10thNight
33%311%26%23%4
1854
11th to 20thNight
35%38%23%24%7%
1775
21st to endNight
35%412%30%17%2
1670
May1st to 10thNight
36%413%26%19%2
1620
11th to 20thNight
39%6%17%23%14%1
1593
21st to endNight
36%6%15%25%15%2
1745
June1st to 10thNight
37%8%14%26%13%3
1620
11th to 20thNight
23%6%24%31%14%2
1620
21st to endNight
32%8%18%25%13%4
1620
July1st to 10thNight
40%8%18%20%13%2
1575
11th to 20thNight
34%6%22%20%12%6%
1566
21st to endNight
35%8%20%24%11%2
1672
August1st to 10thNight
35%8%20%27%10%1
1600
11th to 20thNight
39%6%21%18%15%2
1746
21st to endNight
39%7%17%22%13%2
1980
September1st to 10thNight
37%6%15%22%16%5%
1900
11th to 20thNight
40%5%12%20%22%1
1980
21st to endNight
33%5%8%23%24%7%
1980
October1st to 10thNight
30%37%23%29%8%
1980
11th to 20thNight
35%38%24%23%8%
2056
21st to endNight
35%2324%27%8%
2456
November1st to 10thNight
33%27%24%25%9%
2406
11th to 20thNight
36%26%23%26%8%
2470
21st to endNight
41%26%25%22%4
2470
December1st to 10thNight
50%38%21%15%3
2470
11th to 20thNight
42%26%24%24%2
3044
21st to endNight
55%37%20%14%1
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
24%20%27%23%5%1
270
11th to 20thDay
26%20%31%14%6%2
270
21st to endDay
22%13%41%19%4
297
February1st to 10thDay
24%17%34%17%7%
270
11th to 20thDay
35%13%34%13%41
270
21st to endDay
37%18%32%10%4
225
March1st to 10thDay
25%16%33%18%7%1
275
11th to 20thDay
23%14%30%25%8%
460
21st to endDay
21%11%32%28%8%
470
April1st to 10thDay
16%16%21%31%13%3
420
11th to 20thDay
17%10%30%25%16%2
412
21st to endDay
16%7%30%29%14%5%
420
May1st to 10thDay
14%10%25%28%15%7%
423
11th to 20thDay
13%5%22%27%21%12%
447
21st to endDay
15%414%24%23%20%
485
June1st to 10thDay
12%314%27%28%16%
450
11th to 20thDay
6%411%25%30%25%
450
21st to endDay
10%311%27%27%21%
450
July1st to 10thDay
10%46%21%29%30%
445
11th to 20thDay
12%26%23%30%27%
444
21st to endDay
9%25%22%37%26%
488
August1st to 10thDay
11%37%22%35%21%
446
11th to 20thDay
13%26%27%36%14%
439
21st to endDay
14%26%20%35%23%
495
September1st to 10thDay
11%26%24%35%21%
450
11th to 20thDay
14%310%21%32%20%
450
21st to endDay
14%213%24%34%13%
450
October1st to 10thDay
13%418%23%29%12%
450
11th to 20thDay
14%9%22%28%22%5%
450
21st to endDay
19%6%22%30%19%4
412
November1st to 10thDay
19%5%25%29%17%5%
270
11th to 20thDay
13%12%33%33%8%1
270
21st to endDay
14%11%34%26%14%1
270
December1st to 10thDay
31%9%27%24%9%1
270
11th to 20thDay
17%16%30%25%11%1
270
21st to endDay
29%13%27%22%8%
297
January1st to 10thNight
24%11%36%25%5%
760
11th to 20thNight
23%13%31%26%6%
760
21st to endNight
21%11%34%32%2
836
February1st to 10thNight
20%11%33%31%5%
760
11th to 20thNight
26%14%33%25%2
743
21st to endNight
30%12%34%23%2
628
March1st to 10thNight
20%11%30%34%5%
760
11th to 20thNight
20%10%34%29%7%1
760
21st to endNight
17%11%30%34%8%1
801
April1st to 10thNight
14%8%30%37%10%1
594
11th to 20thNight
16%7%29%34%14%
533
21st to endNight
12%6%25%42%13%1
540
May1st to 10thNight
13%426%36%19%2
540
11th to 20thNight
13%5%18%34%23%6%
531
21st to endNight
11%211%32%37%6%
584
June1st to 10thNight
11%212%33%37%5%
540
11th to 20thNight
6%110%34%37%12%
540
21st to endNight
6%26%35%41%10%
540
July1st to 10thNight
12%35%24%43%12%
525
11th to 20thNight
11%25%26%42%14%
522
21st to endNight
7%27%24%48%12%
591
August1st to 10thNight
7%25%27%48%11%
537
11th to 20thNight
13%25%32%42%7%
534
21st to endNight
13%2328%45%10%
594
September1st to 10thNight
10%39%29%42%9%
640
11th to 20thNight
15%39%27%41%6%
720
21st to endNight
12%213%34%35%4
720
October1st to 10thNight
12%5%15%30%29%8%
720
11th to 20thNight
15%5%22%35%21%2
720
21st to endNight
17%5%18%41%15%3
792
November1st to 10thNight
14%7%19%37%20%3
740
11th to 20thNight
15%8%31%33%12%1
760
21st to endNight
19%9%26%33%12%1
760
December1st to 10thNight
24%12%26%31%7%
760
11th to 20thNight
20%8%28%36%8%
760
21st to endNight
27%9%25%33%6%
836
Page generated at 2024-03-19 23:31:04. Version ac07

Copyright © 2024 Attilla Danko.


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