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 2018-04-23.

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%
16255
32%
49604
24%
16214
71%
16214
44%
25407

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
51%
776
36%
2328
22%
776
65%
776
43%
1216
January16th to endNight
53%
832
39%
2496
25%
832
67%
832
45%
1260
February1st to 15thNight
56%
761
37%
2287
22%
756
71%
756
51%
1098
February16th to endNight
45%
684
35%
2050
18%
684
60%
684
48%
996
March1st to 15thNight
52%
780
33%
2321
19%
780
64%
780
45%
1171
March16th to endNight
51%
702
38%
2158
23%
702
65%
702
48%
1037
April1st to 15thNight
48%
584
36%
1948
22%
584
66%
584
42%
930
April16th to endNight
51%
558
37%
1859
28%
558
68%
558
50%
814
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
75%
537
26%
1980
28%
537
76%
537
30%
1122
October1st to 15thNight
73%
558
32%
1998
33%
558
75%
558
42%
958
October16th to endNight
73%
768
39%
2304
28%
768
79%
768
57%
1073
November1st to 15thNight
67%
852
37%
2372
23%
852
73%
852
60%
1120
November16th to endNight
63%
975
41%
2535
23%
975
72%
975
56%
1284
December1st to 15thNight
57%
975
36%
2535
20%
975
65%
975
48%
1410
December16th to endNight
49%
1007
39%
2671
20%
1007
61%
1007
48%
1409

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%
49871
Night
431332445%7%60%
49829
Cloud CoverDay
5%31332445%7%56%
49869
Night
431332445%7%60%
49829
TransparencyDay
24%5%8%17%24%18%
49591
Night
21%5%9%18%25%19%
49611
SeeingDay
6%7%22%31%24%8%
5927
Night
5%5%20%37%27%3
16265

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
45%13323247%60%
1940
16th to endDay
4322213435%65%
2080
February1st to 15thDay
221222445%5%66%
1900
16th to endDay
122223346%69%
1710
March1st to 15thDay
2324435%45%6%57%
1966
16th to endDay
2312323346%64%
2415
April1st to 15thDay
231231445%6%64%
2330
16th to endDay
2212212245%71%
2215
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
10%5%25%5%345%5%6%44%
1980
October1st to 15thDay
6%313323346%61%
1958
16th to endDay
322313235%71%
1920
November1st to 15thDay
3313212345%68%
1802
16th to endDay
432212135%71%
1755
December1st to 15thDay
5%323224346%62%
1755
16th to endDay
3322223447%63%
1914
January1st to 15thNight
4423324336%60%
2328
16th to endNight
5%313313346%63%
2496
February1st to 15thNight
2313323347%65%
2282
16th to endNight
2212324446%65%
2050
March1st to 15thNight
431322335%6%61%
2321
16th to endNight
3313322346%65%
2158
April1st to 15thNight
4313323346%64%
1948
16th to endNight
2212224245%70%
1859
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
7%5%14425%6%7%9%45%
1980
October1st to 15thNight
6%213312447%61%
1998
16th to endNight
2212212345%71%
2304
November1st to 15thNight
2312213245%70%
2372
16th to endNight
321231223471%
2535
December1st to 15thNight
4323424446%60%
2535
16th to endNight
3413223335%66%
2671

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
45%13323246%60%
1940
16th to endDay
3322313335%65%
2080
February1st to 15thDay
221222445%5%66%
1900
16th to endDay
1212223346%69%
1710
March1st to 15thDay
232443435%7%57%
1966
16th to endDay
2312313346%65%
2413
April1st to 15thDay
231231435%6%64%
2330
16th to endDay
2212212245%72%
2215
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
11%5%25%5%335%5%6%44%
1980
October1st to 15thDay
6%313223346%61%
1958
16th to endDay
322313235%71%
1920
November1st to 15thDay
4312312245%68%
1802
16th to endDay
432212135%71%
1755
December1st to 15thDay
4323224346%62%
1755
16th to endDay
3323223447%63%
1914
January1st to 15thNight
45%23324335%61%
2328
16th to endNight
5%223313346%63%
2496
February1st to 15thNight
2312323347%65%
2282
16th to endNight
222324446%65%
2050
March1st to 15thNight
431332345%7%61%
2321
16th to endNight
3213323346%65%
2158
April1st to 15thNight
4313323436%64%
1948
16th to endNight
2212223245%70%
1859
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
7%5%14425%6%7%9%45%
1980
October1st to 15thNight
6%21332345%7%60%
1998
16th to endNight
322212345%71%
2304
November1st to 15thNight
3212212246%71%
2372
16th to endNight
3212312235%71%
2535
December1st to 15thNight
4213324446%60%
2535
16th to endNight
3413213335%66%
2671

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
25%25%18%31%16%
1941
16th to endDay
20%35%14%34%21%
2080
February1st to 15thDay
16%46%15%26%29%
1901
16th to endDay
15%25%15%32%27%
1710
March1st to 15thDay
23%45%16%25%24%
1966
16th to endDay
19%35%12%30%28%
2415
April1st to 15thDay
19%46%9%29%30%
2330
16th to endDay
14%249%34%34%
2215
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
36%6%10%19%19%7%
1980
October1st to 15thDay
21%6%9%23%20%18%
1958
16th to endDay
16%2416%30%29%
1920
November1st to 15thDay
17%37%21%28%21%
1802
16th to endDay
17%25%17%32%25%
1755
December1st to 15thDay
22%35%18%32%17%
1755
16th to endDay
20%45%21%31%16%
1914
January1st to 15thNight
25%25%15%31%19%
2328
16th to endNight
22%3414%34%20%
2496
February1st to 15thNight
18%36%12%26%32%
2292
16th to endNight
19%36%10%31%29%
2050
March1st to 15thNight
21%35%16%26%26%
2321
16th to endNight
20%35%14%29%28%
2158
April1st to 15thNight
21%36%11%28%28%
1948
16th to endNight
16%35%12%26%35%
1859
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
31%7%15%21%17%6%
1980
October1st to 15thNight
21%5%12%24%18%17%
1998
16th to endNight
15%36%14%28%31%
2304
November1st to 15thNight
14%35%20%34%21%
2372
16th to endNight
17%2413%32%29%
2535
December1st to 15thNight
23%35%19%28%18%
2535
16th to endNight
21%2419%33%18%
2671

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
5%18%25%34%14%
135
16th to endDay
6%18%26%29%12%5%
144
February1st to 15thDay
27%28%29%29%1
135
16th to endDay
5%17%38%25%11%1
120
March1st to 15thDay
27%45%31%10%2
151
16th to endDay
315%43%25%9%2
352
April1st to 15thDay
416%43%25%8%
329
16th to endDay
221%44%25%6%1
288
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
15%212%30%30%8%
135
October1st to 15thDay
15%214%31%25%11%
135
16th to endDay
3224%26%27%16%
144
November1st to 15thDay
10%6%23%29%20%8%
135
16th to endDay
8%11%25%29%16%8%
135
December1st to 15thDay
11%5%27%40%14%1
135
16th to endDay
6%14%35%30%12%
144
January1st to 15thNight
6%5%30%37%17%2
780
16th to endNight
5%9%27%38%17%1
832
February1st to 15thNight
37%29%36%21%1
764
16th to endNight
48%38%37%10%
684
March1st to 15thNight
5%8%28%38%17%1
780
16th to endNight
39%31%39%14%1
702
April1st to 15thNight
5%9%32%39%11%
584
16th to endNight
37%32%44%11%
558
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
9%15%37%40%5%
537
October1st to 15thNight
7%111%41%34%3
558
16th to endNight
5%215%35%31%9%
768
November1st to 15thNight
5%220%36%30%5%
852
16th to endNight
5%6%19%38%26%4
975
December1st to 15thNight
6%5%25%40%18%2
975
16th to endNight
5%10%29%37%14%2
1007
Page generated at 2018-04-24 09:02:58. Version ac04

Copyright 2018 A. Danko


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