South Llano River State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Llano River State Park clear sky chart from 2005-11-06 to 2024-01-22.

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%
23833
28%
74463
18%
23779
59%
23779
38%
40017

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
38%
947
32%
2458
13%
946
49%
946
42%
1424
January11th to 20thNight
36%
912
30%
2432
12%
912
49%
912
39%
1408
January21st to endNight
32%
800
35%
2400
15%
800
49%
800
33%
1365
February1st to 10thNight
33%
720
30%
2160
13%
720
49%
720
35%
1190
February11th to 20thNight
28%
704
25%
2098
10%
700
41%
700
33%
1180
February21st to endNight
23%
592
31%
1776
7%
592
43%
592
31%
986
March1st to 10thNight
25%
674
28%
2114
7%
674
43%
674
31%
1190
March11th to 20thNight
31%
540
25%
1980
13%
540
47%
540
28%
1098
March21st to endNight
25%
594
29%
2178
13%
594
47%
594
34%
1092
April1st to 10thNight
25%
540
29%
1958
12%
540
49%
540
34%
1000
April11th to 20thNight
23%
533
28%
1777
11%
533
45%
533
32%
972
April21st to endNight
24%
540
31%
1777
11%
540
50%
540
38%
923
May1st to 10thNight
30%
540
29%
1620
15%
540
47%
540
38%
905
May11th to 20thNight
40%
531
23%
1593
17%
531
51%
531
35%
934
May21st to endNight
41%
583
23%
1745
13%
582
56%
582
36%
1027
June1st to 10thNight
60%
540
24%
1620
19%
540
72%
540
55%
763
June11th to 20thNight
58%
540
28%
1620
23%
540
70%
540
55%
763
June21st to endNight
67%
540
26%
1620
26%
540
73%
540
46%
844
July1st to 10thNight
74%
525
18%
1575
18%
525
76%
525
36%
916
July11th to 20thNight
80%
522
33%
1566
33%
522
86%
522
59%
724
July21st to endNight
86%
591
29%
1673
33%
558
89%
558
60%
764
August1st to 10thNight
88%
537
30%
1779
36%
534
90%
534
62%
722
August11th to 20thNight
80%
534
27%
1778
34%
534
81%
534
37%
951
August21st to endNight
78%
594
23%
1980
25%
594
80%
594
38%
1051
September1st to 10thNight
75%
540
24%
1966
28%
540
78%
540
36%
1034
September11th to 20thNight
73%
540
23%
1980
27%
540
74%
540
30%
1109
September21st to endNight
70%
540
28%
1980
27%
540
75%
540
36%
1015
October1st to 10thNight
75%
540
36%
1980
35%
540
80%
540
46%
899
October11th to 20thNight
56%
540
37%
1980
29%
540
66%
540
37%
987
October21st to endNight
47%
787
33%
2371
18%
787
57%
787
41%
1272
November1st to 10thNight
52%
836
31%
2316
16%
836
60%
836
45%
1278
November11th to 20thNight
48%
950
29%
2470
13%
950
56%
950
45%
1374
November21st to endNight
40%
950
30%
2470
13%
950
49%
950
36%
1509
December1st to 10thNight
46%
950
33%
2470
15%
950
56%
950
41%
1446
December11th to 20thNight
37%
949
29%
2900
13%
949
47%
949
31%
1777
December21st to endNight
37%
1038
20%
4303
13%
1026
49%
1026
30%
2125

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%2443445%7%53%
74932
Night
8%42342345%7%58%
75036
TransparencyDay
30%6%10%21%22%12%
74658
Night
26%5%11%22%22%14%
74831
SeeingDay
10%8%24%32%21%5%
13743
Night
10%7%31%38%13%1
23845

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
11%424323435%59%
1707
11th to 20thDay
12%6%24323446%54%
1762
21st to endDay
10%5%24424345%58%
1990
February1st to 10thDay
10%7%24424445%55%
1800
11th to 20thDay
12%6%2442445%6%52%
1749
21st to endDay
11%42332445%6%57%
1480
March1st to 10thDay
13%5%35%5%3345%6%48%
1844
11th to 20thDay
12%6%25%42435%6%52%
1980
21st to endDay
11%4235%23435%57%
2178
April1st to 10thDay
9%5%3442445%7%54%
1998
11th to 20thDay
11%5%245%24446%52%
2134
21st to endDay
9%5%25%434445%57%
2182
May1st to 10thDay
11%5%245%3446%8%48%
2340
11th to 20thDay
12%7%26%5%35%45%7%45%
2302
21st to endDay
10%6%35%5%45%5%6%8%44%
2531
June1st to 10thDay
4313435%46%8%58%
2340
11th to 20thDay
42144345%6%10%57%
2340
21st to endDay
6%3246%36%6%8%8%47%
2340
July1st to 10thDay
7%436%8%46%6%7%8%42%
2340
11th to 20thDay
32234345%7%8%59%
2340
21st to endDay
4213435%5%7%10%57%
2542
August1st to 10thDay
1213334449%65%
2149
11th to 20thDay
6%4245%45%6%6%8%50%
2123
21st to endDay
5%425%6%46%6%6%8%48%
2376
September1st to 10thDay
10%5%35%5%45%448%47%
1993
11th to 20thDay
11%5%36%6%446%6%8%44%
1980
21st to endDay
9%4235%3445%6%53%
1980
October1st to 10thDay
5%42443445%8%57%
1980
11th to 20thDay
11%5%25%423345%57%
1967
21st to endDay
11%423323335%62%
1980
November1st to 10thDay
12%6%23323346%56%
1759
11th to 20thDay
8%5%2432345%6%58%
1710
21st to endDay
12%6%25%423346%54%
1710
December1st to 10thDay
12%5%24314347%53%
1710
11th to 20thDay
11%6%25%5%34445%52%
2161
21st to endDay
10%6%2432233461%
3135
January1st to 10thNight
11%5%13323345%59%
2458
11th to 20thNight
10%5%23423346%58%
2432
21st to endNight
12%6%23423346%54%
2400
February1st to 10thNight
9%6%24423447%57%
2160
11th to 20thNight
13%6%1432335%6%55%
2098
21st to endNight
10%5%2332445%7%54%
1776
March1st to 10thNight
11%5%2342445%8%51%
2114
11th to 20thNight
11%424425%45%6%52%
1980
21st to endNight
7%42433335%8%58%
2178
April1st to 10thNight
6%4243345%5%8%58%
1958
11th to 20thNight
10%5%24424346%56%
1777
21st to endNight
9%414323346%61%
1777
May1st to 10thNight
7%42432445%10%54%
1620
11th to 20thNight
10%5%2442446%9%50%
1593
21st to endNight
8%425%43445%10%52%
1745
June1st to 10thNight
22133235%6%11%63%
1620
11th to 20thNight
21113245%6%9%66%
1620
21st to endNight
432342345%10%60%
1620
July1st to 10thNight
5%324435%6%7%12%50%
1620
11th to 20thNight
211222236%9%69%
1620
21st to endNight
211242336%10%66%
1772
August1st to 10thNight
2112222348%75%
1789
11th to 20thNight
44134345%8%10%55%
1778
21st to endNight
43245%25%5%7%10%54%
1980
September1st to 10thNight
6%42443447%9%54%
1966
11th to 20thNight
8%4235%346%6%7%50%
1980
21st to endNight
8%42342346%7%56%
1980
October1st to 10thNight
5%22321335%7%66%
1980
11th to 20thNight
11%423323345%60%
1980
21st to endNight
11%41431233463%
2371
November1st to 10thNight
10%423322346%62%
2316
11th to 20thNight
7%313424447%61%
2470
21st to endNight
12%5%24424447%53%
2470
December1st to 10thNight
11%5%23313446%58%
2470
11th to 20thNight
12%6%24434446%52%
3036
21st to endNight
10%5%24323336%60%
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
29%36%18%27%17%
1708
11th to 20thDay
32%35%16%27%17%
1762
21st to endDay
30%47%12%28%19%
1990
February1st to 10thDay
31%47%14%22%21%
1800
11th to 20thDay
34%47%18%21%17%
1759
21st to endDay
29%47%14%26%20%
1480
March1st to 10thDay
36%48%16%20%16%
1844
11th to 20thDay
35%48%16%19%19%
1980
21st to endDay
30%5%8%17%22%18%
2178
April1st to 10thDay
31%5%9%19%21%15%
1998
11th to 20thDay
34%5%6%17%22%15%
2134
21st to endDay
31%47%21%21%15%
2182
May1st to 10thDay
35%7%9%16%23%11%
2340
11th to 20thDay
38%6%10%21%21%5%
2306
21st to endDay
37%7%11%22%19%4
2531
June1st to 10thDay
24%6%13%31%23%4
2340
11th to 20thDay
23%7%13%28%23%7%
2340
21st to endDay
30%9%12%24%19%6%
2340
July1st to 10thDay
36%9%15%27%11%1
2276
11th to 20thDay
21%8%14%29%24%4
2271
21st to endDay
19%8%22%35%15%1
2401
August1st to 10thDay
17%5%13%40%24%2
2136
11th to 20thDay
31%9%13%29%14%4
2123
21st to endDay
32%8%15%26%15%4
2376
September1st to 10thDay
36%8%10%21%18%8%
1993
11th to 20thDay
38%8%10%20%19%5%
1980
21st to endDay
30%6%10%23%20%11%
1980
October1st to 10thDay
24%7%10%24%25%10%
1980
11th to 20thDay
30%5%8%15%24%19%
1967
21st to endDay
27%3417%28%20%
1980
November1st to 10thDay
30%48%22%22%13%
1759
11th to 20thDay
27%5%8%19%23%18%
1710
21st to endDay
34%35%18%25%15%
1710
December1st to 10thDay
32%47%19%27%11%
1710
11th to 20thDay
35%47%12%24%18%
2159
21st to endDay
28%3416%28%21%
3135
January1st to 10thNight
29%25%15%27%21%
2458
11th to 20thNight
30%35%19%24%19%
2432
21st to endNight
33%35%14%23%22%
2400
February1st to 10thNight
30%48%15%23%21%
2160
11th to 20thNight
32%36%18%22%19%
2098
21st to endNight
30%46%14%23%22%
1776
March1st to 10thNight
31%5%10%17%23%13%
2114
11th to 20thNight
32%6%8%15%20%19%
1980
21st to endNight
26%5%12%20%19%18%
2178
April1st to 10thNight
26%6%10%21%18%19%
1958
11th to 20thNight
30%5%10%18%19%18%
1777
21st to endNight
25%5%10%24%23%13%
1777
May1st to 10thNight
27%7%10%24%21%11%
1620
11th to 20thNight
31%7%13%26%18%6%
1594
21st to endNight
28%9%15%27%18%2
1746
June1st to 10thNight
14%7%18%35%24%3
1620
11th to 20thNight
15%7%16%32%24%7%
1620
21st to endNight
21%6%17%29%20%6%
1620
July1st to 10thNight
24%13%22%28%12%2
1575
11th to 20thNight
13%6%16%33%27%4
1566
21st to endNight
11%7%25%39%18%1
1673
August1st to 10thNight
10%5%17%41%25%2
1779
11th to 20thNight
24%9%17%31%17%3
1778
21st to endNight
24%9%20%27%16%4
1980
September1st to 10thNight
26%8%12%25%20%9%
1966
11th to 20thNight
29%9%16%22%18%5%
1980
21st to endNight
26%6%13%22%21%12%
1980
October1st to 10thNight
18%6%13%27%23%12%
1980
11th to 20thNight
27%49%18%24%18%
1980
21st to endNight
27%36%17%23%23%
2371
November1st to 10thNight
26%39%20%26%15%
2316
11th to 20thNight
23%5%9%22%23%18%
2470
21st to endNight
33%48%16%23%16%
2470
December1st to 10thNight
28%49%20%24%15%
2470
11th to 20thNight
35%45%15%19%21%
3037
21st to endNight
28%45%16%29%19%
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
12%16%41%23%7%1
270
11th to 20thDay
17%15%29%29%9%1
270
21st to endDay
10%16%43%24%7%
267
February1st to 10thDay
18%13%38%21%8%1
240
11th to 20thDay
22%13%40%22%3
240
21st to endDay
17%18%41%20%3
198
March1st to 10thDay
15%18%41%21%4
240
11th to 20thDay
15%17%40%18%9%
240
21st to endDay
16%18%45%14%6%1
264
April1st to 10thDay
16%18%40%23%2
258
11th to 20thDay
14%19%42%22%3
412
21st to endDay
10%19%42%22%5%
442
May1st to 10thDay
11%12%42%29%7%
603
11th to 20thDay
16%8%33%31%11%2
625
21st to endDay
11%8%28%39%12%1
679
June1st to 10thDay
4420%47%22%3
630
11th to 20thDay
3123%50%19%3
630
21st to endDay
4117%41%33%4
630
July1st to 10thDay
7%29%37%38%9%
621
11th to 20thDay
2445%42%7%
618
21st to endDay
315%38%42%12%
680
August1st to 10thDay
36%37%43%11%
447
11th to 20thDay
7%27%34%37%14%
437
21st to endDay
6%6%30%39%18%
495
September1st to 10thDay
11%426%36%22%
283
11th to 20thDay
7%17%24%41%20%
270
21st to endDay
14%2334%34%13%
270
October1st to 10thDay
6%312%35%36%7%
270
11th to 20thDay
11%421%39%21%3
270
21st to endDay
16%13%26%26%18%2
297
November1st to 10thDay
17%7%26%32%16%2
270
11th to 20thDay
15%12%29%24%13%7%
270
21st to endDay
19%18%31%21%10%1
270
December1st to 10thDay
14%8%29%35%10%3
270
11th to 20thDay
14%18%35%24%8%1
270
21st to endDay
14%13%37%27%9%
297
January1st to 10thNight
15%7%37%32%8%
950
11th to 20thNight
15%9%35%34%7%
912
21st to endNight
15%9%39%30%7%
800
February1st to 10thNight
14%11%38%32%4
720
11th to 20thNight
16%12%41%27%3
704
21st to endNight
13%16%46%23%1
592
March1st to 10thNight
15%13%45%24%3
674
11th to 20thNight
13%10%42%29%5%
540
21st to endNight
8%13%53%25%2
594
April1st to 10thNight
7%12%54%25%3
540
11th to 20thNight
10%14%50%24%2
533
21st to endNight
9%11%54%21%5%
540
May1st to 10thNight
7%10%50%29%4
540
11th to 20thNight
11%5%41%35%8%
531
21st to endNight
8%7%41%35%9%
584
June1st to 10thNight
2132%51%14%
540
11th to 20thNight
2137%50%10%
540
21st to endNight
3221%52%20%1
540
July1st to 10thNight
5%110%55%25%3
525
11th to 20thNight
3112%60%24%1
522
21st to endNight
117%60%29%2
591
August1st to 10thNight
115%63%27%2
537
11th to 20thNight
5%16%52%33%3
534
21st to endNight
418%46%36%5%
594
September1st to 10thNight
6%19%46%34%3
540
11th to 20thNight
9%18%43%37%2
540
21st to endNight
9%114%46%28%1
540
October1st to 10thNight
6%115%52%26%
540
11th to 20thNight
11%5%24%44%15%1
540
21st to endNight
11%9%30%33%16%1
787
November1st to 10thNight
12%427%40%15%1
836
11th to 20thNight
10%6%32%36%14%2
950
21st to endNight
13%9%33%33%11%1
950
December1st to 10thNight
14%7%30%40%9%
950
11th to 20thNight
17%10%33%35%6%
950
21st to endNight
12%10%37%34%7%
1045
Page generated at 2024-01-19 08:28:36. Version ac07

Copyright 2024 Attilla Danko


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