Davis Mountains State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Davis Mountains State Park clear sky chart from 2005-11-05 to 2017-09-16.

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
62%
15395
32%
47047
23%
15354
71%
15354
44%
24158

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
50%
716
35%
2148
20%
716
64%
716
42%
1135
January16th to endNight
51%
768
38%
2304
24%
768
65%
768
44%
1174
February1st to 15thNight
55%
701
36%
2107
21%
696
70%
696
50%
1016
February16th to endNight
43%
632
35%
1894
18%
632
59%
632
49%
912
March1st to 15thNight
52%
720
34%
2142
20%
720
64%
720
46%
1072
March16th to endNight
51%
648
38%
1992
23%
648
65%
648
48%
958
April1st to 15thNight
47%
539
34%
1798
21%
539
65%
539
42%
865
April16th to endNight
50%
540
36%
1800
27%
540
68%
540
50%
790
May1st to 15thNight
50%
539
28%
1799
22%
539
64%
539
43%
875
May16th to endNight
63%
561
26%
1757
25%
561
71%
561
40%
933
June1st to 15thNight
75%
540
25%
1620
23%
540
80%
540
49%
808
June16th to endNight
78%
540
25%
1620
25%
540
80%
540
43%
871
July1st to 15thNight
78%
510
19%
1685
23%
510
78%
510
37%
927
July16th to endNight
82%
564
22%
1771
26%
531
83%
531
35%
979
August1st to 15thNight
85%
539
23%
1789
30%
536
86%
536
41%
920
August16th to endNight
81%
573
21%
1910
24%
573
81%
573
29%
1141
September1st to 15thNight
77%
540
20%
1811
23%
540
77%
540
31%
1055
September16th to endNight
76%
495
25%
1826
28%
495
77%
495
31%
1021
October1st to 15thNight
73%
511
33%
1831
34%
511
75%
511
42%
881
October16th to endNight
72%
704
37%
2112
27%
704
78%
704
56%
992
November1st to 15thNight
66%
785
38%
2185
24%
785
72%
785
60%
1028
November16th to endNight
61%
900
38%
2340
21%
900
70%
900
54%
1207
December1st to 15thNight
56%
900
37%
2340
21%
900
65%
900
48%
1288
December16th to endNight
48%
930
38%
2466
18%
930
60%
930
47%
1310

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
5%31332445%7%56%
47670
Night
431332445%7%59%
47272
Cloud CoverDay
5%31332445%7%56%
47668
Night
431332445%7%59%
47272
TransparencyDay
24%5%8%17%24%18%
47390
Night
22%5%9%18%24%19%
47054
SeeingDay
6%7%20%30%26%8%
5243
Night
5%5%21%37%27%3
15405

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
5%5%13323246%60%
1790
16th to endDay
4323213445%63%
1920
February1st to 15thDay
221212445%5%67%
1750
16th to endDay
222222346%70%
1580
March1st to 15thDay
232442435%6%59%
1815
16th to endDay
2312323346%65%
2229
April1st to 15thDay
2312325%45%6%63%
2150
16th to endDay
2212212246%71%
2160
May1st to 15thDay
3212223447%63%
2151
16th to endDay
5%2122235%5%8%61%
2354
June1st to 15thDay
11123245%7%8%62%
2340
16th to endDay
5%323435%6%7%9%47%
2340
July1st to 15thDay
9%4245%38%7%8%8%37%
2169
16th to endDay
6%4245%48%8%8%9%34%
2277
August1st to 15thDay
6%3145%37%8%9%11%37%
2160
16th to endDay
8%6%25%7%47%7%7%9%33%
2292
September1st to 15thDay
12%5%25%6%47%6%7%7%35%
2148
16th to endDay
9%5%25%5%345%5%6%45%
1823
October1st to 15thDay
6%313323346%61%
1795
16th to endDay
422313236%69%
1760
November1st to 15thDay
431321233468%
1660
16th to endDay
5%3231213470%
1620
December1st to 15thDay
4323224246%63%
1620
16th to endDay
3322223447%62%
1767
January1st to 15thNight
4423324335%60%
2148
16th to endNight
5%213313347%61%
2304
February1st to 15thNight
2313323346%65%
2102
16th to endNight
3212324346%66%
1894
March1st to 15thNight
431322335%6%62%
2142
16th to endNight
2313322336%66%
1992
April1st to 15thNight
4313324346%63%
1798
16th to endNight
2212224235%70%
1800
May1st to 15thNight
4213323445%62%
1799
16th to endNight
5%213325%5%6%7%56%
1756
June1st to 15thNight
21134246%8%9%57%
1620
16th to endNight
42124346%8%9%51%
1620
July1st to 15thNight
42135%25%6%8%10%49%
1785
16th to endNight
4214425%6%7%13%46%
1891
August1st to 15thNight
33124346%8%15%46%
1800
16th to endNight
5%3145%46%5%8%11%43%
1910
September1st to 15thNight
8%4134246%7%12%44%
1811
16th to endNight
6%5%14425%6%7%8%47%
1826
October1st to 15thNight
6%213312446%61%
1831
16th to endNight
3212212335%70%
2112
November1st to 15thNight
232212245%71%
2185
16th to endNight
421332223470%
2340
December1st to 15thNight
4322424346%62%
2340
16th to endNight
341321333465%
2466

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
5%5%13323236%60%
1790
16th to endDay
4322313345%64%
1920
February1st to 15thDay
221122345%5%67%
1750
16th to endDay
1212212346%70%
1580
March1st to 15thDay
232443435%6%59%
1815
16th to endDay
2312313346%65%
2227
April1st to 15thDay
231231435%6%63%
2150
16th to endDay
2212212245%72%
2160
May1st to 15thDay
3212324447%64%
2151
16th to endDay
5%1122235%5%8%61%
2354
June1st to 15thDay
11123236%7%8%61%
2340
16th to endDay
5%323435%6%7%9%48%
2340
July1st to 15thDay
9%4246%37%8%7%8%37%
2169
16th to endDay
6%425%6%48%8%8%9%34%
2277
August1st to 15thDay
6%3245%47%8%9%11%37%
2160
16th to endDay
8%5%35%6%5%7%6%7%9%33%
2292
September1st to 15thDay
12%5%25%5%47%6%6%8%35%
2148
16th to endDay
10%5%25%5%335%5%6%45%
1823
October1st to 15thDay
6%313223346%61%
1795
16th to endDay
322313235%70%
1760
November1st to 15thDay
431231224468%
1660
16th to endDay
5%32212135%70%
1620
December1st to 15thDay
4323214345%63%
1620
16th to endDay
3323223447%62%
1767
January1st to 15thNight
4423324345%60%
2148
16th to endNight
5%22331335%6%61%
2304
February1st to 15thNight
2312224346%65%
2102
16th to endNight
3212324346%66%
1894
March1st to 15thNight
4313223347%62%
2142
16th to endNight
2323323346%66%
1992
April1st to 15thNight
4213323336%63%
1798
16th to endNight
2212223245%70%
1800
May1st to 15thNight
4213423446%62%
1799
16th to endNight
5%212325%45%8%56%
1756
June1st to 15thNight
21133246%8%9%57%
1620
16th to endNight
4112435%6%8%10%51%
1620
July1st to 15thNight
4213435%6%7%10%49%
1785
16th to endNight
4313435%6%7%12%46%
1891
August1st to 15thNight
3212435%6%8%16%46%
1800
16th to endNight
5%3145%45%6%8%11%43%
1910
September1st to 15thNight
8%4134246%6%12%44%
1811
16th to endNight
6%414425%6%7%8%47%
1826
October1st to 15thNight
6%21331335%6%61%
1831
16th to endNight
322212335%71%
2112
November1st to 15thNight
3212213245%71%
2185
16th to endNight
4212312235%70%
2340
December1st to 15thNight
4213323346%62%
2340
16th to endNight
341321333466%
2466

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
26%35%17%30%17%
1791
16th to endDay
21%35%14%32%21%
1920
February1st to 15thDay
16%46%14%26%31%
1751
16th to endDay
15%2415%34%27%
1580
March1st to 15thDay
22%35%16%26%24%
1815
16th to endDay
19%25%11%29%30%
2229
April1st to 15thDay
20%46%9%29%30%
2150
16th to endDay
14%249%34%34%
2160
May1st to 15thDay
19%45%12%25%31%
2151
16th to endDay
18%5%8%17%23%25%
2357
June1st to 15thDay
15%5%11%20%26%20%
2340
16th to endDay
27%7%12%20%20%11%
2340
July1st to 15thDay
37%9%13%22%14%1
2040
16th to endDay
37%11%16%25%8%1
2134
August1st to 15thDay
33%10%17%25%12%1
2147
16th to endDay
42%10%15%17%11%2
2292
September1st to 15thDay
41%10%13%18%12%3
2148
16th to endDay
35%6%10%19%19%7%
1823
October1st to 15thDay
21%6%9%23%21%18%
1795
16th to endDay
17%2416%29%29%
1760
November1st to 15thDay
17%36%19%28%23%
1660
16th to endDay
18%25%15%32%26%
1620
December1st to 15thDay
21%35%18%31%18%
1620
16th to endDay
20%45%21%32%15%
1767
January1st to 15thNight
26%35%15%29%20%
2148
16th to endNight
22%3415%33%19%
2304
February1st to 15thNight
18%36%11%26%33%
2112
16th to endNight
19%25%10%32%30%
1894
March1st to 15thNight
21%35%15%27%26%
2142
16th to endNight
20%2414%28%29%
1992
April1st to 15thNight
22%36%11%28%27%
1798
16th to endNight
16%35%12%25%35%
1800
May1st to 15thNight
21%45%15%21%30%
1800
16th to endNight
23%7%10%17%18%22%
1758
June1st to 15thNight
17%7%14%23%24%12%
1620
16th to endNight
23%7%16%20%19%12%
1620
July1st to 15thNight
24%9%17%30%15%2
1685
16th to endNight
25%10%19%30%12%1
1771
August1st to 15thNight
21%8%23%28%17%
1789
16th to endNight
31%11%16%25%12%2
1910
September1st to 15thNight
29%10%19%23%12%5%
1811
16th to endNight
30%7%15%20%18%7%
1826
October1st to 15thNight
22%5%11%23%19%17%
1831
16th to endNight
16%35%13%28%31%
2112
November1st to 15thNight
14%26%18%34%22%
2185
16th to endNight
18%2413%30%30%
2340
December1st to 15thNight
22%35%19%28%19%
2340
16th to endNight
22%2418%34%17%
2466

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
8%20%34%25%11%
90
16th to endDay
9%26%26%23%9%5%
96
February1st to 15thDay
410%23%24%35%2
90
16th to endDay
8%18%28%27%14%2
81
March1st to 15thDay
443%33%13%3
105
16th to endDay
315%46%21%10%3
288
April1st to 15thDay
418%44%22%9%
269
16th to endDay
221%42%25%6%1
270
May1st to 15thDay
315%40%33%6%
288
16th to endDay
4435%36%15%2
441
June1st to 15thDay
1112%43%34%6%
495
16th to endDay
5%16%35%41%9%
495
July1st to 15thDay
8%332%36%17%
314
16th to endDay
7%1428%40%18%
327
August1st to 15thDay
8%219%45%22%
315
16th to endDay
11%1426%37%17%
332
September1st to 15thDay
9%26%31%35%15%
303
16th to endDay
11%29%29%33%13%
92
October1st to 15thDay
18%216%24%25%12%
90
16th to endDay
5%320%28%23%18%
96
November1st to 15thDay
14%10%24%22%20%8%
90
16th to endDay
13%13%30%27%12%3
90
December1st to 15thDay
10%7%26%38%15%1
90
16th to endDay
8%17%35%29%9%
96
January1st to 15thNight
6%5%32%36%16%2
720
16th to endNight
6%9%28%38%16%1
768
February1st to 15thNight
38%29%35%20%1
704
16th to endNight
48%39%35%10%
632
March1st to 15thNight
49%29%36%18%1
720
16th to endNight
39%30%38%15%1
648
April1st to 15thNight
5%9%33%39%10%
539
16th to endNight
37%33%43%11%
540
May1st to 15thNight
5%5%33%42%12%1
540
16th to endNight
4424%46%20%
563
June1st to 15thNight
215%52%27%1
540
16th to endNight
5%17%47%36%2
540
July1st to 15thNight
45%37%49%3
510
16th to endNight
4234%52%4
564
August1st to 15thNight
220%65%9%
539
16th to endNight
5%125%60%6%
573
September1st to 15thNight
8%1224%55%7%
540
16th to endNight
8%15%36%42%5%
495
October1st to 15thNight
7%111%42%32%3
511
16th to endNight
5%315%34%31%9%
704
November1st to 15thNight
4222%34%29%5%
785
16th to endNight
5%6%20%38%25%3
900
December1st to 15thNight
6%5%26%39%18%3
900
16th to endNight
6%10%30%36%13%2
930
Page generated at 2017-09-17 11:05:42. Version ac04

Copyright 2017 A. Danko


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