Big Thicket Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Thicket Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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
51%
23691
22%
74193
17%
23632
56%
23632
29%
45170

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
32%
950
24%
2458
10%
946
41%
946
28%
1629
January11th to 20thNight
33%
908
24%
2360
10%
908
40%
908
29%
1565
January21st to endNight
32%
990
23%
2574
9%
990
39%
990
26%
1769
February1st to 10thNight
29%
900
20%
2340
8%
900
36%
900
24%
1633
February11th to 20thNight
30%
646
20%
2041
10%
643
38%
643
22%
1335
February21st to endNight
24%
444
21%
1628
10%
444
35%
444
16%
1106
March1st to 10thNight
33%
540
21%
1980
14%
540
41%
540
19%
1276
March11th to 20thNight
32%
540
20%
1980
13%
540
42%
540
19%
1263
March21st to endNight
36%
594
21%
2178
16%
594
45%
594
24%
1298
April1st to 10thNight
35%
540
22%
1940
16%
540
45%
540
21%
1233
April11th to 20thNight
38%
533
24%
1775
16%
533
50%
533
25%
1080
April21st to endNight
40%
540
23%
1800
19%
540
48%
540
26%
1092
May1st to 10thNight
42%
540
18%
1800
17%
540
49%
540
24%
1127
May11th to 20thNight
50%
531
23%
1666
23%
531
56%
531
32%
991
May21st to endNight
64%
584
22%
1746
22%
582
68%
582
36%
1024
June1st to 10thNight
76%
540
21%
1620
22%
540
77%
540
40%
910
June11th to 20thNight
77%
540
20%
1620
22%
540
79%
540
41%
885
June21st to endNight
71%
540
16%
1620
19%
540
72%
540
29%
1017
July1st to 10thNight
74%
525
14%
1575
16%
525
74%
525
32%
960
July11th to 20thNight
81%
522
19%
1566
23%
522
81%
522
41%
856
July21st to endNight
81%
591
15%
1673
19%
558
82%
558
36%
960
August1st to 10thNight
88%
537
22%
1601
24%
534
88%
534
51%
788
August11th to 20thNight
85%
534
20%
1767
24%
534
85%
534
34%
988
August21st to endNight
75%
594
16%
1980
19%
594
76%
594
29%
1199
September1st to 10thNight
78%
540
18%
1847
21%
540
79%
540
32%
1041
September11th to 20thNight
70%
540
18%
1980
21%
540
70%
540
24%
1207
September21st to endNight
73%
540
28%
1980
31%
540
74%
540
33%
1055
October1st to 10thNight
72%
702
29%
2142
25%
702
73%
702
42%
1133
October11th to 20thNight
61%
720
33%
2160
23%
720
67%
720
39%
1206
October21st to endNight
55%
792
33%
2376
24%
792
61%
792
40%
1302
November1st to 10thNight
57%
740
28%
2220
23%
740
61%
740
38%
1244
November11th to 20thNight
51%
760
29%
2280
21%
760
57%
760
34%
1326
November21st to endNight
40%
760
27%
2280
18%
760
47%
760
28%
1452
December1st to 10thNight
40%
906
25%
2426
14%
906
46%
906
27%
1618
December11th to 20thNight
33%
948
23%
2873
9%
948
40%
948
22%
1920
December21st to endNight
34%
1040
14%
4341
10%
1026
39%
1026
16%
2682

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%6%45%5%6%8%39%
74984
Night
14%6%2443445%8%47%
74753
TransparencyDay
42%8%11%17%16%6%
74709
Night
36%6%13%19%17%8%
74548
SeeingDay
14%8%20%26%22%10%
13762
Night
15%6%22%32%22%3
23698

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
20%6%25%42445%5%43%
1707
11th to 20thDay
19%6%35%434345%46%
1629
21st to endDay
21%6%35%5%33346%42%
1782
February1st to 10thDay
24%7%45%5%3435%5%35%
1620
11th to 20thDay
25%8%35%423445%37%
1819
21st to endDay
25%8%35%5%33345%37%
1628
March1st to 10thDay
23%8%36%5%335%45%35%
1980
11th to 20thDay
19%8%36%5%35%346%37%
1980
21st to endDay
16%6%36%5%25%446%42%
2178
April1st to 10thDay
16%6%36%5%46%5%5%6%38%
2020
11th to 20thDay
19%7%35%6%345%46%37%
2134
21st to endDay
12%6%36%5%35%5%5%7%43%
2160
May1st to 10thDay
13%6%37%5%46%5%7%8%37%
2160
11th to 20thDay
11%5%25%6%45%6%7%8%41%
2224
21st to endDay
10%6%37%7%47%7%8%10%31%
2531
June1st to 10thDay
8%5%36%7%5%7%8%7%8%35%
2340
11th to 20thDay
6%5%35%7%49%8%8%10%35%
2340
21st to endDay
8%6%37%8%6%9%9%8%9%27%
2340
July1st to 10thDay
10%5%36%9%5%7%7%9%11%27%
2340
11th to 20thDay
8%5%36%8%47%8%9%12%31%
2340
21st to endDay
8%436%7%5%9%8%8%11%32%
2546
August1st to 10thDay
3326%7%48%7%9%13%36%
2328
11th to 20thDay
6%426%6%5%9%7%9%9%36%
2134
21st to endDay
11%426%7%5%8%7%7%9%34%
2376
September1st to 10thDay
9%5%27%7%47%7%6%9%37%
2106
11th to 20thDay
16%6%36%7%35%7%7%8%33%
1980
21st to endDay
12%5%15%5%36%5%6%7%44%
1978
October1st to 10thDay
8%433445%5%47%53%
1800
11th to 20thDay
11%4244345%5%7%50%
1800
21st to endDay
14%5%24423346%52%
1980
November1st to 10thDay
11%5%25%5%45%5%6%6%46%
1858
11th to 20thDay
14%5%36%43445%5%48%
1900
21st to endDay
17%7%36%5%4434444%
1900
December1st to 10thDay
18%7%25%5%34446%41%
1750
11th to 20thDay
17%7%46%6%3445%6%39%
2161
21st to endDay
18%6%25%43345%7%42%
3135
January1st to 10thNight
20%7%34423347%43%
2458
11th to 20thNight
22%5%35%322335%46%
2360
21st to endNight
20%7%35%5%23346%42%
2574
February1st to 10thNight
20%8%45%433346%40%
2340
11th to 20thNight
23%8%33422335%43%
2041
21st to endNight
25%8%35%433445%36%
1628
March1st to 10thNight
21%9%34433446%40%
1980
11th to 20thNight
18%7%35%5%34446%41%
1980
21st to endNight
17%6%24433347%46%
2178
April1st to 10thNight
16%7%35%5%3445%8%41%
1940
11th to 20thNight
18%425%42345%9%44%
1775
21st to endNight
14%7%345%345%5%7%45%
1800
May1st to 10thNight
14%6%25%4345%7%8%41%
1800
11th to 20thNight
12%5%2443445%7%49%
1665
21st to endNight
8%4144345%7%11%48%
1745
June1st to 10thNight
6%4233335%6%11%54%
1620
11th to 20thNight
5%324325%48%13%52%
1620
21st to endNight
8%424445%6%8%11%42%
1620
July1st to 10thNight
7%425%5%35%6%7%13%44%
1620
11th to 20thNight
432343346%12%55%
1620
21st to endNight
5%2235%36%5%8%13%49%
1772
August1st to 10thNight
21123235%6%14%60%
1611
11th to 20thNight
4313446%5%8%13%49%
1767
21st to endNight
8%4245%35%5%6%12%45%
1980
September1st to 10thNight
6%435%4346%6%11%48%
1847
11th to 20thNight
12%5%25%5%45%6%5%8%43%
1980
21st to endNight
9%5%24424447%56%
1980
October1st to 10thNight
6%31442445%6%60%
2142
11th to 20thNight
11%42332345%7%58%
2160
21st to endNight
12%6%23323335%59%
2376
November1st to 10thNight
11%42442435%7%55%
2220
11th to 20thNight
12%5%2442435%7%53%
2280
21st to endNight
16%7%35%5%3345%5%45%
2280
December1st to 10thNight
19%7%35%423446%43%
2426
11th to 20thNight
18%8%35%5%24345%43%
3036
21st to endNight
19%7%25%43345%5%42%
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
42%5%6%18%20%9%
1708
11th to 20thDay
43%46%15%22%10%
1629
21st to endDay
46%45%15%18%12%
1782
February1st to 10thDay
52%46%13%15%10%
1620
11th to 20thDay
50%5%6%13%17%9%
1829
21st to endDay
51%5%6%13%16%9%
1628
March1st to 10thDay
50%5%9%12%17%7%
1980
11th to 20thDay
49%48%11%19%9%
1980
21st to endDay
44%5%7%16%22%6%
2178
April1st to 10thDay
46%6%9%15%16%8%
2020
11th to 20thDay
47%5%9%14%14%10%
2134
21st to endDay
40%7%9%16%23%6%
2160
May1st to 10thDay
43%7%10%16%17%7%
2160
11th to 20thDay
38%8%10%24%18%3
2228
21st to endDay
46%10%13%18%11%2
2531
June1st to 10thDay
42%11%14%19%14%1
2340
11th to 20thDay
39%12%14%21%13%2
2340
21st to endDay
47%13%15%16%8%
2340
July1st to 10thDay
45%13%19%18%5%
2276
11th to 20thDay
41%14%21%18%6%
2271
21st to endDay
40%14%20%21%41
2405
August1st to 10thDay
34%13%19%25%9%
2314
11th to 20thDay
39%13%19%22%7%1
2134
21st to endDay
42%13%18%17%8%2
2376
September1st to 10thDay
41%12%13%17%12%4
2106
11th to 20thDay
46%9%14%14%14%4
1980
21st to endDay
38%6%13%19%15%9%
1978
October1st to 10thDay
31%6%11%19%22%12%
1800
11th to 20thDay
33%5%8%16%24%14%
1800
21st to endDay
34%46%14%25%16%
1980
November1st to 10thDay
37%6%9%18%20%11%
1858
11th to 20thDay
38%5%7%16%21%13%
1900
21st to endDay
44%46%17%19%9%
1900
December1st to 10thDay
45%5%8%18%17%7%
1750
11th to 20thDay
45%5%6%14%19%10%
2159
21st to endDay
41%5%6%15%24%9%
3135
January1st to 10thNight
43%37%15%22%10%
2458
11th to 20thNight
42%36%17%21%11%
2360
21st to endNight
46%36%15%18%13%
2574
February1st to 10thNight
46%5%7%12%18%12%
2340
11th to 20thNight
46%47%15%19%10%
2041
21st to endNight
50%5%6%13%13%13%
1628
March1st to 10thNight
47%5%8%14%17%10%
1980
11th to 20thNight
45%6%11%11%19%8%
1980
21st to endNight
39%5%12%16%21%8%
2178
April1st to 10thNight
44%5%8%18%15%9%
1940
11th to 20thNight
38%6%11%17%16%12%
1775
21st to endNight
39%5%9%20%20%7%
1800
May1st to 10thNight
40%7%13%16%17%8%
1800
11th to 20thNight
35%5%12%24%20%4
1666
21st to endNight
28%9%19%29%13%2
1746
June1st to 10thNight
24%10%20%30%16%1
1620
11th to 20thNight
23%9%18%33%15%2
1620
21st to endNight
32%12%21%25%9%
1620
July1st to 10thNight
32%10%28%25%5%
1575
11th to 20thNight
22%10%35%27%6%
1566
21st to endNight
23%13%32%26%6%
1673
August1st to 10thNight
15%9%32%35%8%
1601
11th to 20thNight
24%13%29%28%7%1
1767
21st to endNight
31%12%24%22%9%2
1980
September1st to 10thNight
28%10%23%23%13%4
1847
11th to 20thNight
38%8%18%17%14%5%
1980
21st to endNight
29%6%14%22%17%11%
1980
October1st to 10thNight
25%5%11%25%21%13%
2142
11th to 20thNight
27%6%8%21%23%15%
2160
21st to endNight
29%39%15%26%19%
2376
November1st to 10thNight
30%412%19%23%11%
2220
11th to 20thNight
32%5%10%18%24%11%
2280
21st to endNight
40%5%9%17%18%11%
2280
December1st to 10thNight
43%49%19%15%9%
2426
11th to 20thNight
44%46%11%21%14%
3037
21st to endNight
43%5%7%13%24%7%
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
26%14%37%16%7%1
270
11th to 20thDay
20%12%37%22%8%1
243
21st to endDay
23%22%33%17%5%
264
February1st to 10thDay
28%17%32%18%4
240
11th to 20thDay
33%18%28%19%3
240
21st to endDay
30%25%32%11%2
198
March1st to 10thDay
25%22%31%16%6%
240
11th to 20thDay
19%24%39%13%5%
240
21st to endDay
24%15%36%20%5%
264
April1st to 10thDay
18%19%33%25%5%
280
11th to 20thDay
25%16%24%21%13%1
412
21st to endDay
17%11%31%27%13%1
420
May1st to 10thDay
17%12%27%29%15%1
423
11th to 20thDay
12%6%26%35%18%3
547
21st to endDay
9%5%27%33%20%5%
679
June1st to 10thDay
8%313%37%28%12%
630
11th to 20thDay
7%216%34%30%10%
630
21st to endDay
10%313%27%30%17%
630
July1st to 10thDay
7%27%27%37%19%
621
11th to 20thDay
7%26%26%36%24%
618
21st to endDay
8%15%26%34%25%
684
August1st to 10thDay
41427%41%24%
626
11th to 20thDay
6%1314%47%29%
448
21st to endDay
11%26%19%32%29%
495
September1st to 10thDay
8%18%21%40%22%
396
11th to 20thDay
14%18%29%31%17%
270
21st to endDay
16%27%29%36%10%
270
October1st to 10thDay
7%316%42%24%8%
270
11th to 20thDay
13%318%37%19%9%
270
21st to endDay
20%8%25%30%13%3
297
November1st to 10thDay
14%6%24%34%20%2
270
11th to 20thDay
16%11%33%30%9%2
270
21st to endDay
23%17%30%20%8%2
270
December1st to 10thDay
20%9%31%24%12%3
270
11th to 20thDay
17%15%40%23%41
270
21st to endDay
21%16%38%18%5%2
297
January1st to 10thNight
23%10%31%28%8%
950
11th to 20thNight
23%9%30%30%8%
908
21st to endNight
22%11%30%31%6%
990
February1st to 10thNight
24%11%31%30%4
900
11th to 20thNight
30%8%31%26%6%
646
21st to endNight
28%9%36%25%2
444
March1st to 10thNight
25%9%30%32%4
540
11th to 20thNight
21%9%34%29%6%
540
21st to endNight
21%8%32%29%9%
594
April1st to 10thNight
17%10%36%30%7%
540
11th to 20thNight
21%9%28%31%12%
533
21st to endNight
17%7%33%32%10%
540
May1st to 10thNight
15%8%29%38%10%
540
11th to 20thNight
13%5%25%40%16%1
531
21st to endNight
7%421%40%26%3
584
June1st to 10thNight
5%28%40%41%3
540
11th to 20thNight
4110%44%36%4
540
21st to endNight
9%29%29%44%7%
540
July1st to 10thNight
6%26%30%47%10%
525
11th to 20thNight
25%32%47%13%
522
21st to endNight
5%1329%49%13%
591
August1st to 10thNight
3229%55%10%
537
11th to 20thNight
4323%56%14%
534
21st to endNight
7%2424%50%13%
594
September1st to 10thNight
7%1425%52%11%
540
11th to 20thNight
11%16%24%49%8%
540
21st to endNight
10%19%31%42%8%
540
October1st to 10thNight
8%212%34%40%5%
702
11th to 20thNight
11%419%39%24%3
720
21st to endNight
13%7%21%35%21%3
792
November1st to 10thNight
12%321%38%24%2
740
11th to 20thNight
14%8%24%38%16%
760
21st to endNight
18%7%30%29%14%1
760
December1st to 10thNight
21%8%26%31%13%1
906
11th to 20thNight
24%9%29%31%7%
950
21st to endNight
23%10%29%30%8%
1045
Page generated at 2024-01-09 06:14:42. Version ac07

Copyright 2024 Attilla Danko


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