Brazosport Planetarium
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brazosport Planetarium clear sky chart from 2005-11-06 to 2024-01-16.

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
55%
23609
22%
74326
18%
23550
60%
23550
29%
45068

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
37%
949
23%
2458
11%
946
45%
946
27%
1668
January11th to 20thNight
38%
930
22%
2418
9%
930
44%
930
28%
1613
January21st to endNight
36%
990
24%
2574
10%
990
43%
990
26%
1757
February1st to 10thNight
33%
801
20%
2241
9%
801
40%
801
23%
1564
February11th to 20thNight
37%
668
19%
2062
11%
664
43%
664
24%
1326
February21st to endNight
29%
444
21%
1628
11%
444
38%
444
17%
1077
March1st to 10thNight
40%
540
22%
1980
15%
540
49%
540
22%
1222
March11th to 20thNight
42%
540
18%
1980
14%
540
48%
540
20%
1257
March21st to endNight
46%
594
24%
2178
19%
594
56%
594
27%
1220
April1st to 10thNight
40%
540
22%
1980
18%
540
49%
540
23%
1213
April11th to 20thNight
43%
533
22%
1826
17%
533
52%
533
25%
1105
April21st to endNight
45%
540
23%
1800
20%
540
53%
540
25%
1096
May1st to 10thNight
48%
540
21%
1796
20%
540
54%
540
27%
1079
May11th to 20thNight
60%
531
24%
1594
24%
531
64%
531
36%
922
May21st to endNight
64%
583
23%
1746
25%
582
67%
582
36%
1004
June1st to 10thNight
79%
540
22%
1620
27%
540
79%
540
42%
869
June11th to 20thNight
79%
540
20%
1620
23%
540
81%
540
40%
890
June21st to endNight
73%
540
14%
1620
18%
540
73%
540
30%
1008
July1st to 10thNight
73%
525
14%
1575
17%
525
73%
525
30%
990
July11th to 20thNight
86%
522
19%
1566
23%
522
86%
522
43%
843
July21st to endNight
86%
591
19%
1673
21%
558
87%
558
40%
925
August1st to 10thNight
91%
537
24%
1601
26%
534
92%
534
51%
786
August11th to 20thNight
82%
534
22%
1707
26%
534
82%
534
38%
937
August21st to endNight
79%
594
18%
2041
21%
594
79%
594
32%
1151
September1st to 10thNight
77%
540
16%
1980
19%
540
77%
540
27%
1151
September11th to 20thNight
67%
540
19%
1980
22%
540
67%
540
23%
1249
September21st to endNight
74%
540
27%
1980
30%
540
74%
540
30%
1102
October1st to 10thNight
76%
623
30%
2063
29%
623
77%
623
40%
1063
October11th to 20thNight
68%
720
33%
2160
26%
720
71%
720
42%
1172
October21st to endNight
62%
792
33%
2376
25%
792
66%
792
38%
1310
November1st to 10thNight
66%
740
28%
2220
23%
740
67%
740
37%
1271
November11th to 20thNight
55%
760
27%
2280
20%
760
60%
760
32%
1367
November21st to endNight
48%
769
27%
2289
19%
769
55%
769
27%
1495
December1st to 10thNight
45%
950
25%
2470
14%
950
50%
950
28%
1660
December11th to 20thNight
37%
949
21%
2882
11%
948
41%
948
21%
1957
December21st to endNight
34%
1040
14%
4362
10%
1026
41%
1026
16%
2749

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
12%6%35%5%45%6%7%9%39%
74973
Night
12%5%25%5%3445%8%47%
74856
TransparencyDay
39%8%14%20%14%5%
74698
Night
36%6%13%21%16%8%
74651
SeeingDay
13%5%20%30%23%10%
13622
Night
15%418%31%27%5%
23617

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
19%6%35%5%35%5%5%6%39%
1707
11th to 20thDay
18%7%34333447%44%
1670
21st to endDay
19%8%35%5%3445%5%39%
1782
February1st to 10thDay
21%8%46%5%445%5%6%33%
1732
11th to 20thDay
22%8%35%43345%6%35%
1784
21st to endDay
20%8%46%43345%7%37%
1628
March1st to 10thDay
19%7%36%5%34447%37%
1980
11th to 20thDay
17%7%37%5%23347%41%
1980
21st to endDay
16%5%35%435%45%7%44%
2178
April1st to 10thDay
16%7%46%5%2446%8%37%
1980
11th to 20thDay
17%7%36%5%35%46%8%38%
2080
21st to endDay
11%6%35%5%35%5%5%8%44%
2160
May1st to 10thDay
11%6%36%5%45%6%6%8%41%
2160
11th to 20thDay
10%6%26%5%45%7%7%9%39%
2301
21st to endDay
9%5%36%7%47%8%9%12%30%
2531
June1st to 10thDay
5%425%6%46%7%8%10%43%
2340
11th to 20thDay
6%425%6%5%8%8%9%11%37%
2340
21st to endDay
8%5%25%7%6%8%9%9%14%28%
2340
July1st to 10thDay
10%5%35%7%46%8%10%12%31%
2340
11th to 20thDay
5%426%6%47%8%9%13%36%
2340
21st to endDay
5%435%7%47%7%9%12%36%
2546
August1st to 10thDay
3325%446%9%9%13%43%
2328
11th to 20thDay
4416%6%47%9%11%13%35%
2190
21st to endDay
8%436%7%5%8%8%10%11%31%
2309
September1st to 10thDay
8%6%36%8%5%7%8%7%9%33%
1980
11th to 20thDay
14%6%47%7%5%6%6%9%7%30%
1980
21st to endDay
9%6%36%5%46%5%6%7%43%
1980
October1st to 10thDay
5%5%245%45%5%6%9%49%
1877
11th to 20thDay
10%6%25%5%345%5%7%49%
1800
21st to endDay
11%424423447%53%
1980
November1st to 10thDay
9%6%25%446%6%6%9%43%
1858
11th to 20thDay
15%6%345%245%5%6%45%
1900
21st to endDay
17%5%36%6%345%5%6%40%
1886
December1st to 10thDay
17%6%25%4345%5%8%39%
1710
11th to 20thDay
14%6%36%5%445%6%8%40%
2161
21st to endDay
17%6%35%5%245%47%42%
3135
January1st to 10thNight
19%6%25%5%34345%44%
2458
11th to 20thNight
18%7%25%43433446%
2418
21st to endNight
19%6%35%434447%42%
2574
February1st to 10thNight
19%8%36%434447%37%
2241
11th to 20thNight
19%9%35%423437%43%
2062
21st to endNight
20%8%25%6%43445%38%
1628
March1st to 10thNight
17%9%35%423446%42%
1980
11th to 20thNight
15%8%35%5%35%45%7%40%
1980
21st to endNight
14%5%24424447%50%
2178
April1st to 10thNight
14%7%35%5%3445%7%42%
1980
11th to 20thNight
16%4245%2445%7%45%
1826
21st to endNight
12%6%35%6%36%5%5%7%43%
1800
May1st to 10thNight
12%6%26%4246%5%10%42%
1796
11th to 20thNight
9%4145%345%6%10%49%
1593
21st to endNight
7%5%35%4346%7%13%45%
1745
June1st to 10thNight
6%42443336%12%54%
1620
11th to 20thNight
5%4233345%9%12%49%
1620
21st to endNight
6%425%6%36%5%8%14%40%
1620
July1st to 10thNight
6%5%25%7%45%6%7%13%41%
1620
11th to 20thNight
3223335%5%6%13%55%
1620
21st to endNight
3223445%5%8%12%52%
1772
August1st to 10thNight
211232447%12%63%
1611
11th to 20thNight
44244245%7%13%52%
1707
21st to endNight
6%4245%345%6%12%49%
2041
September1st to 10thNight
6%425%6%346%8%13%44%
1980
11th to 20thNight
12%6%26%6%35%5%5%8%42%
1980
21st to endNight
8%425%5%3346%10%50%
1980
October1st to 10thNight
5%32442445%8%58%
2063
11th to 20thNight
9%41442435%7%59%
2160
21st to endNight
10%42442443459%
2376
November1st to 10thNight
9%4145%345%47%54%
2220
11th to 20thNight
13%5%245%3445%6%49%
2280
21st to endNight
14%6%26%5%345%45%45%
2289
December1st to 10thNight
18%7%345%2445%8%41%
2470
11th to 20thNight
16%8%36%5%3445%7%38%
3036
21st to endNight
16%7%37%5%34445%43%
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
46%5%6%16%19%8%
1708
11th to 20thDay
41%5%7%19%18%11%
1670
21st to endDay
47%46%17%16%10%
1782
February1st to 10thDay
51%6%7%14%13%10%
1732
11th to 20thDay
50%5%9%13%15%7%
1794
21st to endDay
47%7%10%14%14%8%
1628
March1st to 10thDay
46%7%11%15%16%5%
1980
11th to 20thDay
44%6%10%14%17%8%
1980
21st to endDay
39%7%13%15%20%7%
2178
April1st to 10thDay
44%7%11%18%14%7%
1980
11th to 20thDay
43%7%11%17%14%8%
2080
21st to endDay
37%7%12%22%17%6%
2160
May1st to 10thDay
37%9%14%20%14%6%
2160
11th to 20thDay
37%8%14%22%16%3
2305
21st to endDay
39%10%15%24%11%1
2531
June1st to 10thDay
29%9%18%29%16%
2340
11th to 20thDay
33%10%16%28%12%1
2340
21st to endDay
38%13%18%25%6%
2340
July1st to 10thDay
37%13%22%23%5%
2276
11th to 20thDay
33%11%29%22%6%
2271
21st to endDay
31%13%26%26%4
2405
August1st to 10thDay
24%11%26%32%7%
2314
11th to 20thDay
31%15%25%23%5%
2190
21st to endDay
39%13%20%21%6%1
2309
September1st to 10thDay
42%11%15%18%12%2
1980
11th to 20thDay
47%10%12%17%14%1
1980
21st to endDay
37%6%13%19%18%6%
1980
October1st to 10thDay
28%8%12%25%20%8%
1877
11th to 20thDay
32%6%8%22%18%12%
1800
21st to endDay
32%46%19%24%15%
1980
November1st to 10thDay
35%7%12%20%21%7%
1858
11th to 20thDay
40%5%10%17%17%11%
1900
21st to endDay
44%5%9%17%15%10%
1886
December1st to 10thDay
42%7%11%20%14%6%
1710
11th to 20thDay
41%6%10%16%18%10%
2159
21st to endDay
42%7%8%14%18%11%
3135
January1st to 10thNight
43%5%6%14%21%11%
2458
11th to 20thNight
43%47%15%20%13%
2418
21st to endNight
44%5%5%16%19%12%
2574
February1st to 10thNight
48%5%8%10%16%13%
2241
11th to 20thNight
44%48%16%17%12%
2062
21st to endNight
49%47%13%17%9%
1628
March1st to 10thNight
43%5%11%19%15%8%
1980
11th to 20thNight
44%6%12%13%16%8%
1980
21st to endNight
34%5%12%19%21%9%
2178
April1st to 10thNight
41%6%11%19%17%7%
1980
11th to 20thNight
38%6%11%19%14%12%
1826
21st to endNight
39%6%11%20%17%7%
1800
May1st to 10thNight
37%7%13%20%16%8%
1796
11th to 20thNight
30%6%14%27%19%3
1594
21st to endNight
30%6%20%29%13%1
1746
June1st to 10thNight
24%6%20%31%19%
1620
11th to 20thNight
25%8%17%34%15%2
1620
21st to endNight
33%10%24%24%9%
1620
July1st to 10thNight
35%9%25%26%5%
1575
11th to 20thNight
22%9%34%29%7%
1566
21st to endNight
23%9%29%33%4
1673
August1st to 10thNight
15%9%28%41%7%
1601
11th to 20thNight
24%10%29%32%6%
1707
21st to endNight
28%10%25%28%8%1
2041
September1st to 10thNight
31%11%22%20%12%4
1980
11th to 20thNight
41%7%14%22%13%2
1980
21st to endNight
31%7%14%22%19%6%
1980
October1st to 10thNight
25%6%12%27%19%11%
2063
11th to 20thNight
26%5%9%26%22%12%
2160
21st to endNight
29%46%17%26%18%
2376
November1st to 10thNight
30%6%12%23%21%9%
2220
11th to 20thNight
36%412%20%19%10%
2280
21st to endNight
41%6%8%20%17%8%
2289
December1st to 10thNight
42%5%10%21%14%8%
2470
11th to 20thNight
45%5%9%13%14%15%
3037
21st to endNight
44%6%5%15%21%9%
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
23%9%38%22%6%2
270
11th to 20thDay
22%11%33%27%7%1
257
21st to endDay
20%11%39%23%6%
264
February1st to 10thDay
28%12%34%18%7%1
240
11th to 20thDay
26%12%33%23%6%
240
21st to endDay
22%13%47%14%3
198
March1st to 10thDay
23%12%40%22%3
240
11th to 20thDay
18%14%46%18%31
240
21st to endDay
17%15%39%25%3
264
April1st to 10thDay
21%12%38%23%6%
240
11th to 20thDay
22%15%25%23%13%1
358
21st to endDay
15%6%35%30%13%1
420
May1st to 10thDay
17%5%32%30%14%1
423
11th to 20thDay
12%329%37%15%4
624
21st to endDay
8%324%43%19%3
679
June1st to 10thDay
7%313%42%26%10%
630
11th to 20thDay
9%112%43%26%9%
630
21st to endDay
10%38%34%31%13%
630
July1st to 10thDay
9%2431%34%20%
621
11th to 20thDay
41229%38%25%
618
21st to endDay
5%2331%39%21%
684
August1st to 10thDay
32225%44%25%
626
11th to 20thDay
4218%45%31%
504
21st to endDay
10%2317%38%30%
428
September1st to 10thDay
11%2325%41%17%
270
11th to 20thDay
12%1429%33%20%
270
21st to endDay
10%37%30%36%13%
270
October1st to 10thDay
6%110%45%28%9%
270
11th to 20thDay
10%216%35%27%10%
270
21st to endDay
16%6%26%31%18%2
297
November1st to 10thDay
11%321%41%17%5%
270
11th to 20thDay
20%6%26%31%15%3
270
21st to endDay
21%9%38%20%10%2
270
December1st to 10thDay
20%432%29%13%3
270
11th to 20thDay
20%11%36%25%9%
270
21st to endDay
20%8%41%19%11%2
297
January1st to 10thNight
23%6%28%31%11%
950
11th to 20thNight
22%7%27%34%9%1
930
21st to endNight
22%7%30%33%9%
990
February1st to 10thNight
25%7%28%33%7%
801
11th to 20thNight
23%9%26%33%10%
668
21st to endNight
23%10%32%29%6%
444
March1st to 10thNight
21%6%28%34%11%1
540
11th to 20thNight
19%5%27%39%9%1
540
21st to endNight
18%5%27%37%13%1
594
April1st to 10thNight
16%5%31%36%11%
540
11th to 20thNight
19%6%26%36%13%
533
21st to endNight
16%6%26%37%14%1
540
May1st to 10thNight
16%327%41%12%
540
11th to 20thNight
11%123%44%20%2
531
21st to endNight
8%316%42%28%2
584
June1st to 10thNight
7%1437%46%5%
540
11th to 20thNight
6%15%41%41%6%
540
21st to endNight
9%16%25%47%13%
540
July1st to 10thNight
7%1421%52%15%
525
11th to 20thNight
31115%58%23%
522
21st to endNight
42217%60%16%
591
August1st to 10thNight
1113%69%16%
537
11th to 20thNight
5%110%66%18%
534
21st to endNight
8%1116%56%18%
594
September1st to 10thNight
7%1214%58%18%
540
11th to 20thNight
15%1319%50%13%
540
21st to endNight
9%15%24%52%9%
540
October1st to 10thNight
6%18%35%40%10%
623
11th to 20thNight
10%213%39%30%5%
720
21st to endNight
12%416%40%25%4
792
November1st to 10thNight
11%215%39%28%5%
740
11th to 20thNight
16%419%38%21%2
760
21st to endNight
17%425%34%17%2
769
December1st to 10thNight
21%6%21%31%19%2
950
11th to 20thNight
24%6%25%34%11%
950
21st to endNight
21%8%29%31%11%1
1045
Page generated at 2024-01-13 18:28:29. Version ac07

Copyright 2024 Attilla Danko


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