San Angelo State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the San Angelo State Park clear sky chart from 2005-11-05 to 2019-06-10.

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%
17819
31%
53936
20%
17777
62%
17777
44%
27721

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 15thNight
42%
1047
34%
2717
14%
1045
55%
1045
45%
1531
January16th to endNight
40%
924
38%
2716
18%
924
57%
924
45%
1373
February1st to 15thNight
36%
823
32%
2469
15%
819
52%
819
40%
1313
February16th to endNight
29%
736
31%
2206
10%
736
46%
736
36%
1184
March1st to 15thNight
33%
774
31%
2454
13%
774
49%
774
36%
1329
March16th to endNight
33%
672
30%
2464
16%
672
52%
672
38%
1158
April1st to 15thNight
29%
629
32%
2140
13%
629
54%
629
39%
1060
April16th to endNight
34%
624
32%
2079
15%
624
58%
624
45%
983
May1st to 15thNight
38%
629
28%
1893
17%
629
54%
629
41%
1017
May16th to endNight
46%
657
27%
1972
18%
657
62%
657
46%
1015
June1st to 15thNight
61%
612
26%
1836
20%
612
72%
612
58%
848
June16th to endNight
72%
585
27%
1755
28%
585
74%
585
55%
832
July1st to 15thNight
78%
555
25%
1665
25%
555
82%
555
50%
839
July16th to endNight
86%
612
33%
1758
39%
579
88%
579
61%
790
August1st to 15thNight
86%
575
31%
1908
38%
572
88%
572
53%
859
August16th to endNight
80%
621
27%
2070
31%
621
82%
621
43%
1039
September1st to 15thNight
74%
585
25%
2096
29%
585
77%
585
34%
1140
September16th to endNight
67%
582
30%
2145
28%
582
73%
582
35%
1111
October1st to 15thNight
64%
585
36%
2145
32%
585
71%
585
45%
979
October16th to endNight
57%
747
38%
2411
24%
747
68%
747
48%
1149
November1st to 15thNight
55%
1025
33%
2665
16%
1025
62%
1025
52%
1421
November16th to endNight
48%
1050
35%
2730
16%
1050
58%
1050
48%
1501
December1st to 15thNight
44%
1050
35%
2730
16%
1050
55%
1050
43%
1560
December16th to endNight
40%
1120
32%
2912
13%
1120
51%
1120
41%
1690

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
8%313323346%57%
54568
Night
7%313323347%60%
54137
Cloud CoverDay
8%313323346%57%
54566
Night
7%312323347%60%
54137
TransparencyDay
27%39%22%24%12%
54268
Night
23%39%22%25%15%
53940
SeeingDay
9%5%22%33%23%6%
7669
Night
8%5%29%38%16%
17826

By Month

Percentage Cloud Cover SW (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 15thDay
11%414422235%57%
1881
16th to endDay
8%312224346%60%
2223
February1st to 15thDay
7%314314335%59%
2050
16th to endDay
10%5%12323235%58%
1840
March1st to 15thDay
11%5%13324335%54%
2166
16th to endDay
7%423323236%60%
2464
April1st to 15thDay
6%213323347%61%
2464
16th to endDay
8%413312345%60%
2486
May1st to 15thDay
9%424424346%52%
2717
16th to endDay
9%42432335%7%52%
2846
June1st to 15thDay
322323448%64%
2653
16th to endDay
5%323325%46%8%55%
2535
July1st to 15thDay
6%2135%45%5%6%8%49%
2535
16th to endDay
3212335%5%5%9%57%
2649
August1st to 15thDay
211332435%8%62%
2294
16th to endDay
6%325%5%46%5%6%9%45%
2484
September1st to 15thDay
10%4245%345%5%8%44%
2194
16th to endDay
11%3145%24446%50%
2145
October1st to 15thDay
8%413313335%61%
2145
16th to endDay
8%21321222468%
2148
November1st to 15thDay
7%412213336%62%
1853
16th to endDay
6%41331223464%
1890
December1st to 15thDay
12%5%13412335%55%
1890
16th to endDay
10%6%23313335%54%
2016
January1st to 15thNight
9%413212336%60%
2717
16th to endNight
7%313222245%64%
2716
February1st to 15thNight
9%413312236%60%
2462
16th to endNight
9%413323246%58%
2206
March1st to 15thNight
10%5%13323345%56%
2454
16th to endNight
6%313213347%61%
2464
April1st to 15thNight
6%313323446%61%
2140
16th to endNight
6%212213336%65%
2079
May1st to 15thNight
6%32322446%7%55%
1892
16th to endNight
431221336%9%58%
1971
June1st to 15thNight
21122346%8%65%
1836
16th to endNight
21122135%5%8%64%
1755
July1st to 15thNight
42232446%11%58%
1755
16th to endNight
221222336%11%61%
1867
August1st to 15thNight
11232345%8%64%
1919
16th to endNight
42123235%6%12%54%
2070
September1st to 15thNight
8%31343446%8%51%
2096
16th to endNight
9%324323348%53%
2145
October1st to 15thNight
8%311212236%64%
2145
16th to endNight
7%31221223368%
2411
November1st to 15thNight
6%31221224466%
2665
16th to endNight
7%312322335%63%
2730
December1st to 15thNight
11%413222246%57%
2730
16th to endNight
9%5%23323346%56%
2912

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 15thDay
11%414423235%57%
1881
16th to endDay
8%312223345%61%
2223
February1st to 15thDay
7%314323436%59%
2050
16th to endDay
10%5%22313335%58%
1840
March1st to 15thDay
11%5%23324345%54%
2166
16th to endDay
7%413323336%60%
2462
April1st to 15thDay
6%213213347%61%
2464
16th to endDay
8%323312345%60%
2486
May1st to 15thDay
10%42442435%5%52%
2717
16th to endDay
9%42432345%7%52%
2846
June1st to 15thDay
4112313448%64%
2653
16th to endDay
6%312325%36%8%55%
2535
July1st to 15thDay
6%224435%5%6%7%49%
2535
16th to endDay
32123345%6%9%58%
2649
August1st to 15thDay
211332435%8%63%
2294
16th to endDay
5%4145%45%6%6%9%45%
2484
September1st to 15thDay
11%3245%35%5%5%7%45%
2194
16th to endDay
11%315%5%34445%50%
2145
October1st to 15thDay
9%313323235%60%
2145
16th to endDay
8%21221223468%
2148
November1st to 15thDay
8%413213336%62%
1853
16th to endDay
7%313222335%64%
1890
December1st to 15thDay
12%6%13313326%55%
1890
16th to endDay
9%6%24324335%54%
2016
January1st to 15thNight
9%323212336%60%
2717
16th to endNight
8%312222236%64%
2716
February1st to 15thNight
9%413312235%60%
2462
16th to endNight
10%412223346%58%
2206
March1st to 15thNight
10%5%13313345%56%
2454
16th to endNight
6%312313337%61%
2464
April1st to 15thNight
6%312413346%60%
2140
16th to endNight
6%212213345%65%
2079
May1st to 15thNight
7%31322446%6%56%
1892
16th to endNight
5%21222246%10%58%
1971
June1st to 15thNight
211121346%9%64%
1836
16th to endNight
21122135%5%8%64%
1755
July1st to 15thNight
421232446%10%58%
1755
16th to endNight
211221436%11%62%
1867
August1st to 15thNight
11232345%8%64%
1919
16th to endNight
42123335%7%10%54%
2070
September1st to 15thNight
8%41343446%7%51%
2096
16th to endNight
9%414323347%53%
2145
October1st to 15thNight
9%211212246%64%
2145
16th to endNight
7%31221233368%
2411
November1st to 15thNight
6%312212245%66%
2665
16th to endNight
8%312313335%63%
2730
December1st to 15thNight
11%323223336%57%
2730
16th to endNight
9%423323345%56%
2912

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 15thDay
30%25%21%26%13%
1882
16th to endDay
25%25%16%33%16%
2223
February1st to 15thDay
28%16%19%23%21%
2051
16th to endDay
30%2317%28%17%
1840
March1st to 15thDay
32%25%17%26%16%
2166
16th to endDay
26%37%24%23%15%
2464
April1st to 15thDay
24%28%18%25%20%
2464
16th to endDay
27%26%17%26%19%
2486
May1st to 15thDay
33%39%19%19%14%
2717
16th to endDay
30%39%23%22%9%
2850
June1st to 15thDay
19%410%28%28%9%
2653
16th to endDay
25%413%26%22%7%
2535
July1st to 15thDay
29%6%16%30%13%3
2396
16th to endDay
19%5%17%36%18%2
2495
August1st to 15thDay
19%5%14%31%25%3
2281
16th to endDay
32%6%16%24%17%3
2484
September1st to 15thDay
36%5%11%23%17%5%
2194
16th to endDay
34%47%19%23%9%
2145
October1st to 15thDay
25%310%24%24%11%
2145
16th to endDay
21%25%16%33%21%
2148
November1st to 15thDay
24%28%27%23%14%
1853
16th to endDay
23%25%17%30%21%
1890
December1st to 15thDay
32%16%18%26%14%
1890
16th to endDay
32%25%21%27%10%
2016
January1st to 15thNight
26%25%17%29%18%
2717
16th to endNight
23%1417%31%21%
2716
February1st to 15thNight
27%17%15%23%23%
2472
16th to endNight
28%25%16%27%20%
2206
March1st to 15thNight
30%26%18%23%18%
2454
16th to endNight
23%311%23%23%15%
2464
April1st to 15thNight
23%39%20%20%21%
2140
16th to endNight
21%39%22%26%16%
2079
May1st to 15thNight
25%412%21%21%13%
1893
16th to endNight
21%5%15%25%22%9%
1973
June1st to 15thNight
15%315%29%27%7%
1836
16th to endNight
16%415%28%26%8%
1755
July1st to 15thNight
20%416%34%18%4
1665
16th to endNight
13%319%34%25%3
1758
August1st to 15thNight
16%313%30%28%5%
1908
16th to endNight
22%5%16%27%21%5%
2070
September1st to 15thNight
29%6%13%22%21%6%
2096
16th to endNight
30%310%23%21%11%
2145
October1st to 15thNight
21%313%25%23%13%
2145
16th to endNight
21%2416%31%23%
2411
November1st to 15thNight
21%27%26%24%17%
2665
16th to endNight
23%2416%29%23%
2730
December1st to 15thNight
29%17%20%24%16%
2730
16th to endNight
29%25%20%27%15%
2912

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 15thDay
15%431%35%12%1
180
16th to endDay
5%11%37%29%11%4
192
February1st to 15thDay
15%5%43%25%9%1
180
16th to endDay
16%6%42%27%6%
159
March1st to 15thDay
18%8%40%22%10%
180
16th to endDay
49%35%31%15%3
192
April1st to 15thDay
6%16%41%27%6%
343
16th to endDay
8%14%39%26%8%1
378
May1st to 15thDay
12%8%34%34%8%1
614
16th to endDay
11%7%31%33%13%1
677
June1st to 15thDay
3118%50%22%3
616
16th to endDay
3112%38%35%7%
570
July1st to 15thDay
5%17%38%35%11%
550
16th to endDay
2232%47%14%
570
August1st to 15thDay
4131%45%16%
359
16th to endDay
9%17%28%37%15%
396
September1st to 15thDay
6%2327%37%22%
229
16th to endDay
19%16%26%31%15%
180
October1st to 15thDay
8%18%42%33%5%
180
16th to endDay
17%122%25%25%7%
192
November1st to 15thDay
18%5%25%32%12%5%
180
16th to endDay
11%13%27%23%16%7%
180
December1st to 15thDay
22%5%23%35%10%2
180
16th to endDay
18%11%36%22%11%
192
January1st to 15thNight
11%5%34%36%11%
1050
16th to endNight
8%8%37%35%8%
924
February1st to 15thNight
12%8%39%31%7%
824
16th to endNight
12%11%44%29%1
736
March1st to 15thNight
13%9%40%31%5%
774
16th to endNight
5%11%47%30%4
672
April1st to 15thNight
6%10%51%28%3
629
16th to endNight
5%7%49%31%6%
624
May1st to 15thNight
8%6%42%36%5%
630
16th to endNight
5%439%37%12%
659
June1st to 15thNight
2230%51%13%
612
16th to endNight
2217%55%20%1
585
July1st to 15thNight
6%8%49%32%2
555
16th to endNight
2356%35%1
612
August1st to 15thNight
1443%45%4
575
16th to endNight
5%6%39%44%3
621
September1st to 15thNight
8%16%38%41%3
585
16th to endNight
11%11%43%31%
582
October1st to 15thNight
9%221%44%22%
585
16th to endNight
8%425%40%18%2
747
November1st to 15thNight
8%5%26%40%17%
1025
16th to endNight
9%6%32%35%14%1
1050
December1st to 15thNight
14%5%32%37%9%
1050
16th to endNight
12%9%33%37%7%
1120
Page generated at 2019-06-10 18:29:47. Version ac04

Copyright 2019 A. Danko


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