Hill Country State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hill Country State Natural Area clear sky chart from 2005-11-05 to 2018-03-21.

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
52%
16150
26%
49216
19%
16107
59%
16107
34%
28423

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
45%
970
28%
2522
14%
970
52%
970
35%
1565
January16th to endNight
43%
884
30%
2548
17%
884
53%
884
33%
1512
February1st to 15thNight
39%
764
29%
2287
15%
758
50%
758
32%
1301
February16th to endNight
31%
684
26%
2050
11%
684
44%
684
30%
1194
March1st to 15thNight
35%
648
27%
2208
15%
648
48%
648
28%
1274
March16th to endNight
34%
594
24%
2178
16%
594
46%
594
26%
1242
April1st to 15thNight
31%
539
24%
1964
15%
539
46%
539
28%
1097
April16th to endNight
31%
540
26%
1766
15%
540
47%
540
29%
1067
May1st to 15thNight
33%
539
21%
1620
14%
539
43%
539
29%
990
May16th to endNight
46%
562
24%
1684
20%
561
56%
561
31%
1048
June1st to 15thNight
66%
540
22%
1620
23%
540
72%
540
49%
819
June16th to endNight
64%
540
21%
1620
21%
540
69%
540
39%
931
July1st to 15thNight
73%
510
20%
1530
21%
510
76%
510
38%
872
July16th to endNight
79%
564
24%
1594
27%
531
83%
531
42%
877
August1st to 15thNight
86%
539
27%
1768
33%
536
86%
536
49%
839
August16th to endNight
73%
573
20%
1934
24%
573
75%
573
30%
1154
September1st to 15thNight
74%
540
19%
1980
23%
540
75%
540
30%
1140
September16th to endNight
64%
537
23%
1980
25%
537
65%
537
26%
1182
October1st to 15thNight
71%
540
32%
1980
32%
540
74%
540
39%
984
October16th to endNight
62%
725
38%
2261
28%
725
68%
725
48%
1106
November1st to 15thNight
54%
828
26%
2348
16%
828
59%
828
36%
1393
November16th to endNight
55%
975
32%
2535
17%
975
62%
975
43%
1458
December1st to 15thNight
48%
975
29%
2535
17%
975
52%
975
33%
1602
December16th to endNight
40%
1040
24%
2704
12%
1040
47%
1040
30%
1776

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%5%24424446%44%
49620
Night
12%423323346%52%
49417
Cloud CoverDay
14%5%24424447%45%
49618
Night
12%423323346%52%
49417
TransparencyDay
38%5%9%18%17%9%
49318
Night
31%5%11%20%18%12%
49222
SeeingDay
16%419%30%23%5%
5887
Night
15%5%22%37%18%1
16157

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
16%6%24313235%49%
1746
16th to endDay
15%5%22323335%52%
2038
February1st to 15thDay
16%6%24313335%48%
1900
16th to endDay
18%5%24313345%46%
1710
March1st to 15thDay
19%6%24312245%46%
2080
16th to endDay
19%5%23222345%47%
2173
April1st to 15thDay
16%5%24424346%46%
1980
16th to endDay
16%6%25%434346%43%
2193
May1st to 15thDay
17%6%25%5%3445%7%38%
2331
16th to endDay
19%6%35%5%2435%7%36%
2430
June1st to 15thDay
6%424435%5%6%9%45%
2340
16th to endDay
11%6%25%6%47%6%6%8%35%
2340
July1st to 15thDay
11%5%35%5%35%5%6%8%39%
2340
16th to endDay
8%325%5%36%6%6%10%40%
2466
August1st to 15thDay
3212425%5%6%11%53%
2178
16th to endDay
8%5%26%6%47%6%6%8%37%
2267
September1st to 15thDay
11%6%26%7%45%6%6%6%36%
1980
16th to endDay
12%5%25%5%3446%7%40%
1980
October1st to 15thDay
10%5%23334436%50%
1980
16th to endDay
9%31331333462%
1950
November1st to 15thDay
17%8%34323446%41%
1836
16th to endDay
14%5%2332322355%
1755
December1st to 15thDay
20%7%23323236%43%
1755
16th to endDay
18%7%23323325%46%
1872
January1st to 15thNight
16%5%23323335%52%
2522
16th to endNight
15%424313346%51%
2548
February1st to 15thNight
15%5%13312225%55%
2282
16th to endNight
15%5%14323337%49%
2050
March1st to 15thNight
15%5%24323245%49%
2208
16th to endNight
17%5%2231343451%
2178
April1st to 15thNight
15%5%22323336%51%
1964
16th to endNight
17%414413336%48%
1766
May1st to 15thNight
14%5%2342335%7%47%
1619
16th to endNight
14%42342335%9%46%
1683
June1st to 15thNight
42232335%8%62%
1620
16th to endNight
8%32332335%9%53%
1620
July1st to 15thNight
6%3235%3446%8%50%
1620
16th to endNight
6%213315%46%10%54%
1702
August1st to 15thNight
211332345%9%63%
1778
16th to endNight
7%314435%5%5%9%47%
1934
September1st to 15thNight
7%425%425%36%9%47%
1980
16th to endNight
10%6%25%5%2435%7%45%
1980
October1st to 15thNight
9%32322346%59%
1980
16th to endNight
7%312212235%66%
2261
November1st to 15thNight
12%5%23323345%53%
2348
16th to endNight
13%312212245%60%
2535
December1st to 15thNight
18%5%23213236%49%
2535
16th to endNight
17%7%2422333447%
2704

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
16%6%23313326%50%
1746
16th to endDay
15%422323236%52%
2038
February1st to 15thDay
16%5%24313335%49%
1900
16th to endDay
18%5%14314345%47%
1710
March1st to 15thDay
19%6%24312245%46%
2080
16th to endDay
20%5%23313335%47%
2171
April1st to 15thDay
16%5%14424436%46%
1980
16th to endDay
17%5%24434446%43%
2193
May1st to 15thDay
18%5%245%34447%38%
2331
16th to endDay
21%6%25%42345%7%36%
2430
June1st to 15thDay
7%424435%5%5%9%46%
2340
16th to endDay
13%5%35%6%37%5%6%8%35%
2340
July1st to 15thDay
11%5%35%5%35%5%6%7%40%
2340
16th to endDay
9%4246%37%5%5%10%40%
2466
August1st to 15thDay
32123345%6%11%54%
2178
16th to endDay
9%5%26%6%47%5%6%8%37%
2267
September1st to 15thDay
11%5%36%6%45%5%6%6%37%
1980
16th to endDay
13%5%35%5%345%5%7%40%
1980
October1st to 15thDay
11%5%23334346%51%
1980
16th to endDay
9%31332223462%
1950
November1st to 15thDay
18%7%2442335%5%42%
1836
16th to endDay
15%42321332355%
1755
December1st to 15thDay
20%6%24314235%44%
1755
16th to endDay
18%7%13323326%46%
1872
January1st to 15thNight
16%423322335%52%
2522
16th to endNight
15%424313245%51%
2548
February1st to 15thNight
16%41331223455%
2282
16th to endNight
16%5%23323337%50%
2050
March1st to 15thNight
15%5%24313245%50%
2208
16th to endNight
17%5%22313345%51%
2178
April1st to 15thNight
16%413313335%52%
1964
16th to endNight
18%413323435%49%
1766
May1st to 15thNight
14%5%2242435%7%47%
1619
16th to endNight
15%42341435%8%46%
1683
June1st to 15thNight
5%21221345%8%62%
1620
16th to endNight
8%32432335%10%53%
1620
July1st to 15thNight
6%3235%2446%8%51%
1620
16th to endNight
6%21332446%10%53%
1702
August1st to 15thNight
211331335%9%63%
1778
16th to endNight
8%414435%5%6%9%47%
1934
September1st to 15thNight
8%5%25%325%46%9%47%
1980
16th to endNight
11%6%245%2345%6%46%
1980
October1st to 15thNight
10%33313345%60%
1980
16th to endNight
8%312211235%66%
2261
November1st to 15thNight
13%423323345%53%
2348
16th to endNight
13%411212236%59%
2535
December1st to 15thNight
18%5%22213236%49%
2535
16th to endNight
18%6%3331333447%
2704

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
37%35%17%21%15%
1747
16th to endDay
35%36%15%24%15%
2038
February1st to 15thDay
39%35%14%18%18%
1901
16th to endDay
39%46%15%21%13%
1710
March1st to 15thDay
40%37%15%17%14%
2080
16th to endDay
39%47%17%18%12%
2173
April1st to 15thDay
39%48%14%18%15%
1980
16th to endDay
41%46%17%16%12%
2193
May1st to 15thDay
43%5%10%15%17%7%
2331
16th to endDay
46%5%9%17%16%3
2434
June1st to 15thDay
31%7%13%22%19%5%
2340
16th to endDay
44%7%11%19%14%2
2340
July1st to 15thDay
38%6%14%25%13%1
2201
16th to endDay
33%8%19%28%9%
2311
August1st to 15thDay
22%7%16%36%15%1
2164
16th to endDay
40%8%15%23%8%2
2267
September1st to 15thDay
42%8%12%16%16%2
1980
16th to endDay
41%6%10%17%15%8%
1980
October1st to 15thDay
33%5%11%19%21%9%
1980
16th to endDay
25%36%16%26%21%
1950
November1st to 15thDay
43%38%18%15%11%
1836
16th to endDay
35%3414%20%21%
1755
December1st to 15thDay
43%37%15%19%10%
1755
16th to endDay
41%37%15%22%10%
1872
January1st to 15thNight
35%26%16%19%19%
2522
16th to endNight
35%25%15%22%18%
2548
February1st to 15thNight
33%26%15%20%21%
2292
16th to endNight
35%37%15%21%16%
2050
March1st to 15thNight
35%48%15%18%16%
2208
16th to endNight
35%5%9%16%19%13%
2178
April1st to 15thNight
34%49%16%18%17%
1964
16th to endNight
37%410%18%15%13%
1766
May1st to 15thNight
35%6%12%18%15%11%
1620
16th to endNight
35%6%13%25%13%5%
1685
June1st to 15thNight
18%6%15%29%25%4
1620
16th to endNight
27%7%19%26%15%3
1620
July1st to 15thNight
27%8%19%30%13%1
1530
16th to endNight
21%10%24%31%11%1
1594
August1st to 15thNight
16%7%22%38%14%
1768
16th to endNight
32%9%21%24%10%2
1934
September1st to 15thNight
32%7%16%21%17%4
1980
16th to endNight
37%6%13%20%14%7%
1980
October1st to 15thNight
25%414%25%18%11%
1980
16th to endNight
21%36%16%29%23%
2261
November1st to 15thNight
32%410%20%19%12%
2348
16th to endNight
27%37%16%21%22%
2535
December1st to 15thNight
36%37%18%21%12%
2535
16th to endNight
40%36%14%20%14%
2704

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
22%9%28%32%7%
135
16th to endDay
18%11%31%28%9%
144
February1st to 15thDay
23%13%21%25%14%1
135
16th to endDay
29%10%31%23%5%
120
March1st to 15thDay
28%11%35%19%5%
135
16th to endDay
16%7%36%35%4
113
April1st to 15thDay
16%14%33%32%31
99
16th to endDay
16%9%40%28%5%
303
May1st to 15thDay
22%9%35%27%5%
468
16th to endDay
25%427%29%11%1
517
June1st to 15thDay
8%14%45%27%3
495
16th to endDay
14%111%36%30%6%
495
July1st to 15thDay
11%12%34%35%5%
475
16th to endDay
7%6%25%46%12%
515
August1st to 15thDay
4233%42%16%
333
16th to endDay
11%28%35%28%13%
307
September1st to 15thDay
6%224%51%15%
135
16th to endDay
12%6%21%45%14%
135
October1st to 15thDay
46%38%35%14%
135
16th to endDay
13%6%17%33%25%4
144
November1st to 15thDay
36%418%21%17%2
135
16th to endDay
18%9%28%22%16%3
135
December1st to 15thDay
27%6%22%22%16%5%
135
16th to endDay
30%7%28%26%6%
144
January1st to 15thNight
19%8%22%36%11%
975
16th to endNight
18%6%26%36%11%
884
February1st to 15thNight
20%10%25%32%10%
764
16th to endNight
21%8%36%30%3
684
March1st to 15thNight
18%7%34%33%5%
648
16th to endNight
18%8%36%31%5%
594
April1st to 15thNight
16%6%43%31%2
539
16th to endNight
17%6%42%26%6%
540
May1st to 15thNight
15%7%40%29%5%
540
16th to endNight
14%430%39%10%
563
June1st to 15thNight
423%52%17%
540
16th to endNight
7%119%47%22%1
540
July1st to 15thNight
6%10%46%34%
510
16th to endNight
6%448%37%3
564
August1st to 15thNight
2344%44%3
539
16th to endNight
8%17%38%40%4
573
September1st to 15thNight
9%6%40%37%5%
540
16th to endNight
13%110%38%32%3
537
October1st to 15thNight
10%112%43%29%3
540
16th to endNight
9%421%32%27%4
725
November1st to 15thNight
14%420%36%22%2
828
16th to endNight
16%5%19%38%19%2
975
December1st to 15thNight
21%7%20%35%14%1
975
16th to endNight
22%7%24%32%11%
1040
Page generated at 2018-03-22 10:34:25. Version ac04

Copyright 2018 A. Danko


Hill Country State Natural Area Clear Sky Chart |Charts Home