Blanco State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blanco 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
47%
23797
26%
74433
17%
23739
55%
23739
32%
43147

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
36%
949
31%
2458
12%
946
47%
946
36%
1471
January11th to 20thNight
33%
950
28%
2470
10%
950
44%
950
32%
1554
January21st to endNight
34%
865
31%
2465
12%
865
48%
865
29%
1513
February1st to 10thNight
28%
720
28%
2160
10%
720
43%
720
27%
1311
February11th to 20thNight
28%
704
23%
2098
10%
700
38%
700
27%
1275
February21st to endNight
19%
592
27%
1776
7%
592
36%
592
24%
1114
March1st to 10thNight
27%
586
24%
2026
10%
586
42%
586
22%
1246
March11th to 20thNight
32%
540
23%
1980
15%
540
43%
540
22%
1188
March21st to endNight
28%
594
25%
2178
14%
594
44%
594
25%
1232
April1st to 10thNight
28%
540
24%
1980
12%
540
46%
540
24%
1156
April11th to 20thNight
26%
533
22%
1919
11%
533
42%
533
23%
1157
April21st to endNight
28%
540
27%
1683
14%
540
46%
540
27%
1036
May1st to 10thNight
31%
540
26%
1620
17%
540
43%
540
28%
1003
May11th to 20thNight
39%
531
23%
1594
18%
531
49%
531
32%
976
May21st to endNight
44%
583
22%
1745
16%
582
56%
582
30%
1085
June1st to 10thNight
65%
540
25%
1620
23%
540
73%
540
46%
835
June11th to 20thNight
58%
540
24%
1620
23%
540
66%
540
46%
849
June21st to endNight
66%
540
23%
1620
25%
540
70%
540
39%
918
July1st to 10thNight
68%
525
16%
1575
18%
525
70%
525
33%
935
July11th to 20thNight
81%
522
27%
1566
29%
522
84%
522
48%
799
July21st to endNight
79%
591
25%
1673
27%
558
84%
558
51%
836
August1st to 10thNight
85%
537
29%
1632
32%
534
86%
534
61%
726
August11th to 20thNight
78%
534
25%
1778
29%
534
80%
534
38%
940
August21st to endNight
76%
594
21%
2056
24%
594
77%
594
35%
1123
September1st to 10thNight
73%
540
22%
1980
25%
540
74%
540
32%
1095
September11th to 20thNight
67%
540
22%
1980
23%
540
69%
540
27%
1164
September21st to endNight
67%
540
26%
1980
26%
540
71%
540
33%
1058
October1st to 10thNight
71%
540
33%
1980
36%
540
73%
540
39%
974
October11th to 20thNight
55%
620
32%
2060
23%
620
63%
620
33%
1167
October21st to endNight
47%
792
33%
2376
19%
792
56%
792
38%
1325
November1st to 10thNight
54%
740
29%
2220
19%
740
59%
740
34%
1313
November11th to 20thNight
48%
907
27%
2427
14%
907
54%
907
38%
1438
November21st to endNight
35%
950
27%
2470
11%
950
44%
950
31%
1595
December1st to 10thNight
42%
950
31%
2470
15%
950
50%
950
36%
1521
December11th to 20thNight
34%
949
26%
2893
12%
948
42%
948
24%
1872
December21st to endNight
36%
1039
18%
4305
12%
1026
45%
1026
24%
2347

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
11%6%25%5%3445%7%47%
74955
Night
12%6%24424447%52%
75010
TransparencyDay
38%39%21%19%10%
74680
Night
35%310%21%20%12%
74805
SeeingDay
14%8%22%31%21%5%
13728
Night
15%8%26%35%14%1
23806

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%7%23423445%54%
1707
11th to 20thDay
17%7%23422446%50%
1710
21st to endDay
14%6%24324336%53%
1940
February1st to 10thDay
17%6%35%32335%5%46%
1800
11th to 20thDay
16%7%35%323446%45%
1749
21st to endDay
18%5%2442334451%
1480
March1st to 10thDay
17%7%36%42445%6%41%
1934
11th to 20thDay
14%8%25%434445%46%
1980
21st to endDay
14%6%35%423446%48%
2178
April1st to 10thDay
13%8%36%5%35%446%44%
1980
11th to 20thDay
20%6%3443335%6%44%
1985
21st to endDay
14%6%25%434446%47%
2276
May1st to 10thDay
13%7%46%5%45%5%5%7%39%
2340
11th to 20thDay
14%9%46%6%46%446%38%
2302
21st to endDay
16%7%35%6%35%6%7%8%34%
2531
June1st to 10thDay
5%4245%37%6%6%9%48%
2340
11th to 20thDay
7%5%246%45%6%6%8%48%
2340
21st to endDay
7%5%36%7%5%7%5%7%10%39%
2340
July1st to 10thDay
10%5%36%7%47%6%7%8%37%
2340
11th to 20thDay
5%224436%5%8%10%51%
2340
21st to endDay
5%323435%6%7%11%52%
2546
August1st to 10thDay
2212435%4410%63%
2292
11th to 20thDay
6%425%6%35%46%8%51%
2123
21st to endDay
5%4247%46%7%7%11%43%
2300
September1st to 10thDay
10%6%36%6%45%5%46%45%
1980
11th to 20thDay
11%6%26%7%46%6%7%7%39%
1980
21st to endDay
8%425%5%345%6%7%49%
1980
October1st to 10thDay
7%5%24435%5%5%6%53%
1980
11th to 20thDay
13%5%244245%5%7%51%
1880
21st to endDay
11%325%423345%57%
1980
November1st to 10thDay
12%8%36%5%3346%6%45%
1858
11th to 20thDay
11%5%25%5%2445%6%50%
1748
21st to endDay
17%6%25%5%24446%47%
1710
December1st to 10thDay
13%7%35%324345%49%
1710
11th to 20thDay
14%8%25%5%3445%5%45%
2161
21st to endDay
14%7%2431333456%
3135
January1st to 10thNight
16%42322335%6%54%
2458
11th to 20thNight
15%6%24323345%53%
2470
21st to endNight
16%6%24423345%50%
2465
February1st to 10thNight
16%7%36%323346%49%
2160
11th to 20thNight
17%6%25%422335%50%
2098
21st to endNight
18%6%35%433345%47%
1776
March1st to 10thNight
16%8%25%434447%44%
2026
11th to 20thNight
16%7%35%433436%46%
1980
21st to endNight
14%6%3443345%6%49%
2178
April1st to 10thNight
10%8%35%43445%7%47%
1980
11th to 20thNight
16%7%26%5%23346%47%
1919
21st to endNight
16%6%34424336%48%
1683
May1st to 10thNight
12%6%35%4345%47%47%
1620
11th to 20thNight
12%6%35%5%2445%8%46%
1593
21st to endNight
13%6%244345%6%11%42%
1745
June1st to 10thNight
5%31333346%9%60%
1620
11th to 20thNight
432332445%9%60%
1620
21st to endNight
6%434425%36%11%52%
1620
July1st to 10thNight
9%5%25%5%25%5%6%11%46%
1620
11th to 20thNight
32124245%5%10%62%
1620
21st to endNight
431332445%12%59%
1772
August1st to 10thNight
1112323449%71%
1642
11th to 20thNight
5%414425%47%10%54%
1778
21st to endNight
5%4245%35%46%10%51%
2056
September1st to 10thNight
7%5%245%35%46%8%52%
1980
11th to 20thNight
9%6%36%5%35%46%8%45%
1980
21st to endNight
7%6%2443447%7%52%
1980
October1st to 10thNight
6%424424447%59%
1980
11th to 20thNight
13%5%24325%446%53%
2060
21st to endNight
15%5%1432222460%
2376
November1st to 10thNight
11%7%35%323346%53%
2220
11th to 20thNight
9%6%2442335%6%55%
2427
21st to endNight
17%6%24433345%47%
2470
December1st to 10thNight
13%6%34313347%52%
2470
11th to 20thNight
15%9%35%423335%47%
3036
21st to endNight
17%7%23223235%55%
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
34%2321%23%16%
1708
11th to 20thDay
39%35%15%22%17%
1710
21st to endDay
36%35%13%27%16%
1940
February1st to 10thDay
42%3413%22%16%
1800
11th to 20thDay
41%36%19%18%14%
1759
21st to endDay
39%15%18%19%17%
1480
March1st to 10thDay
46%29%14%19%12%
1934
11th to 20thDay
41%36%14%19%16%
1980
21st to endDay
38%38%19%20%12%
2178
April1st to 10thDay
43%27%19%17%11%
1980
11th to 20thDay
44%25%17%20%12%
1985
21st to endDay
42%3422%19%11%
2276
May1st to 10thDay
45%38%17%20%7%
2340
11th to 20thDay
48%37%19%18%4
2306
21st to endDay
47%5%10%22%15%1
2531
June1st to 10thDay
31%412%29%20%4
2340
11th to 20thDay
33%410%29%18%5%
2340
21st to endDay
41%6%10%23%17%4
2340
July1st to 10thDay
42%6%13%26%11%1
2276
11th to 20thDay
27%418%28%20%3
2271
21st to endDay
25%420%36%14%1
2405
August1st to 10thDay
19%415%41%21%1
2278
11th to 20thDay
30%316%33%13%4
2123
21st to endDay
34%6%15%28%13%4
2300
September1st to 10thDay
40%49%22%17%8%
1980
11th to 20thDay
43%5%10%20%17%5%
1980
21st to endDay
34%49%23%19%12%
1980
October1st to 10thDay
32%310%21%24%11%
1980
11th to 20thDay
35%37%16%21%18%
1880
21st to endDay
32%2316%26%20%
1980
November1st to 10thDay
41%26%21%19%11%
1858
11th to 20thDay
37%36%19%22%14%
1748
21st to endDay
42%35%15%21%14%
1710
December1st to 10thDay
39%27%20%23%9%
1710
11th to 20thDay
43%27%11%22%15%
2159
21st to endDay
35%2415%29%16%
3135
January1st to 10thNight
33%25%17%24%19%
2458
11th to 20thNight
37%3417%23%17%
2470
21st to endNight
39%2315%21%20%
2465
February1st to 10thNight
40%25%13%22%18%
2160
11th to 20thNight
40%25%17%19%17%
2098
21st to endNight
42%3415%18%18%
1776
March1st to 10thNight
43%38%16%20%11%
2026
11th to 20thNight
43%37%13%18%16%
1980
21st to endNight
38%39%18%18%14%
2178
April1st to 10thNight
38%48%18%17%14%
1980
11th to 20thNight
42%38%14%18%15%
1919
21st to endNight
40%38%20%19%10%
1683
May1st to 10thNight
40%39%21%18%10%
1620
11th to 20thNight
37%411%26%17%5%
1594
21st to endNight
38%5%14%27%15%1
1746
June1st to 10thNight
23%415%32%22%3
1620
11th to 20thNight
24%414%32%22%5%
1620
21st to endNight
29%5%17%29%15%3
1620
July1st to 10thNight
32%8%20%29%11%1
1575
11th to 20thNight
20%6%20%32%21%1
1566
21st to endNight
19%5%28%37%10%1
1673
August1st to 10thNight
13%423%40%19%1
1632
11th to 20thNight
27%6%21%31%12%3
1778
21st to endNight
30%5%21%29%12%3
2056
September1st to 10thNight
32%6%15%23%18%7%
1980
11th to 20thNight
37%5%15%23%15%5%
1980
21st to endNight
32%413%20%19%11%
1980
October1st to 10thNight
26%311%26%22%12%
1980
11th to 20thNight
34%38%16%20%19%
2060
21st to endNight
31%1417%24%22%
2376
November1st to 10thNight
35%36%20%23%13%
2220
11th to 20thNight
32%38%21%20%16%
2427
21st to endNight
41%27%16%20%15%
2470
December1st to 10thNight
35%28%20%22%12%
2470
11th to 20thNight
43%1412%20%19%
3037
21st to endNight
36%2314%30%15%
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
20%16%35%24%41
270
11th to 20thDay
25%14%31%23%7%1
270
21st to endDay
16%18%39%21%5%
267
February1st to 10thDay
26%16%31%23%4
240
11th to 20thDay
25%20%34%18%3
240
21st to endDay
27%19%39%15%
198
March1st to 10thDay
22%18%39%18%2
240
11th to 20thDay
20%16%38%20%6%
240
21st to endDay
18%20%39%17%5%1
264
April1st to 10thDay
19%17%43%18%3
240
11th to 20thDay
21%19%34%21%5%
263
21st to endDay
19%15%38%22%6%
536
May1st to 10thDay
15%15%36%28%6%
603
11th to 20thDay
20%8%29%32%8%2
625
21st to endDay
17%7%27%34%15%1
679
June1st to 10thDay
7%317%42%26%4
630
11th to 20thDay
9%117%48%21%3
630
21st to endDay
9%312%40%30%6%
630
July1st to 10thDay
9%211%35%33%9%
621
11th to 20thDay
5%16%37%45%7%
618
21st to endDay
316%37%43%11%
684
August1st to 10thDay
31439%42%11%
590
11th to 20thDay
8%1437%40%10%
437
21st to endDay
415%30%41%20%
419
September1st to 10thDay
10%15%26%42%16%
270
11th to 20thDay
6%2429%43%16%
270
21st to endDay
11%27%31%36%12%
270
October1st to 10thDay
6%117%36%29%9%
270
11th to 20thDay
11%428%34%20%4
270
21st to endDay
19%13%28%23%14%3
297
November1st to 10thDay
19%7%26%34%10%4
270
11th to 20thDay
23%11%24%28%11%3
270
21st to endDay
25%18%30%18%7%2
270
December1st to 10thDay
14%11%35%28%9%3
270
11th to 20thDay
19%17%33%23%7%
270
21st to endDay
19%14%35%25%6%1
297
January1st to 10thNight
19%11%32%32%7%1
950
11th to 20thNight
20%11%31%31%6%
950
21st to endNight
21%11%32%30%7%
865
February1st to 10thNight
22%13%33%26%6%
720
11th to 20thNight
23%12%36%26%3
704
21st to endNight
24%13%41%20%2
592
March1st to 10thNight
21%13%35%28%4
586
11th to 20thNight
20%12%32%32%4
540
21st to endNight
18%11%41%26%4
594
April1st to 10thNight
13%14%41%27%4
540
11th to 20thNight
19%12%38%28%2
533
21st to endNight
19%10%41%23%8%1
540
May1st to 10thNight
14%13%38%30%4
540
11th to 20thNight
14%6%36%34%8%1
531
21st to endNight
15%5%31%37%11%
584
June1st to 10thNight
6%321%49%21%1
540
11th to 20thNight
6%131%46%14%1
540
21st to endNight
7%416%49%21%4
540
July1st to 10thNight
10%310%46%27%4
525
11th to 20thNight
419%56%30%2
522
21st to endNight
5%19%51%30%3
591
August1st to 10thNight
119%53%33%4
537
11th to 20thNight
7%16%50%31%5%
534
21st to endNight
6%17%44%36%5%
594
September1st to 10thNight
9%19%43%33%5%
540
11th to 20thNight
12%211%37%36%4
540
21st to endNight
11%114%35%35%3
540
October1st to 10thNight
8%214%46%28%3
540
11th to 20thNight
14%5%21%40%18%2
620
21st to endNight
16%9%25%28%20%2
792
November1st to 10thNight
14%6%22%40%17%1
740
11th to 20thNight
13%8%26%37%15%1
907
21st to endNight
20%11%29%29%10%1
950
December1st to 10thNight
19%9%29%33%9%1
950
11th to 20thNight
23%10%29%32%7%
950
21st to endNight
20%10%30%33%7%
1045
Page generated at 2024-01-19 08:28:31. Version ac07

Copyright 2024 Attilla Danko


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