Devils River State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Devils River State Natural Area clear sky chart from 2005-11-05 to 2017-09-18.

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
50%
15411
29%
46997
19%
15368
61%
15368
41%
25060

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
43%
853
29%
2284
15%
852
51%
852
39%
1358
January16th to endNight
42%
768
33%
2304
18%
768
56%
768
37%
1282
February1st to 15thNight
40%
704
32%
2107
15%
698
55%
698
40%
1102
February16th to endNight
28%
632
31%
1894
9%
632
47%
632
41%
981
March1st to 15thNight
32%
674
31%
2114
13%
674
49%
674
38%
1113
March16th to endNight
29%
576
27%
2112
15%
576
46%
576
34%
1103
April1st to 15thNight
25%
539
30%
1819
12%
539
48%
539
37%
947
April16th to endNight
27%
540
32%
1800
13%
540
53%
540
40%
919
May1st to 15thNight
30%
539
24%
1676
13%
539
46%
539
35%
937
May16th to endNight
40%
561
25%
1684
15%
561
55%
561
35%
991
June1st to 15thNight
60%
540
24%
1620
20%
540
68%
540
58%
755
June16th to endNight
62%
540
24%
1620
23%
540
68%
540
43%
879
July1st to 15thNight
73%
510
22%
1530
24%
510
75%
510
41%
849
July16th to endNight
80%
564
30%
1695
34%
531
85%
531
50%
818
August1st to 15thNight
88%
539
30%
1789
37%
536
89%
536
53%
798
August16th to endNight
78%
573
26%
1910
29%
573
80%
573
37%
1023
September1st to 15thNight
79%
540
22%
1929
27%
540
80%
540
36%
1044
September16th to endNight
68%
501
25%
1848
26%
501
71%
501
32%
1005
October1st to 15thNight
60%
495
35%
1815
30%
495
69%
495
43%
850
October16th to endNight
59%
588
37%
1996
26%
588
68%
588
49%
907
November1st to 15thNight
54%
875
31%
2275
15%
875
62%
875
50%
1245
November16th to endNight
51%
900
35%
2340
17%
900
58%
900
49%
1266
December1st to 15thNight
49%
900
31%
2340
18%
900
55%
900
40%
1400
December16th to endNight
40%
960
30%
2496
14%
960
50%
960
39%
1488

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
9%423323446%53%
47778
Night
7%313323347%58%
47209
Cloud CoverDay
9%423323446%53%
47776
Night
7%313323347%58%
47209
TransparencyDay
30%5%10%20%20%11%
47486
Night
25%5%11%21%21%15%
47004
SeeingDay
10%422%38%20%3
5331
Night
9%431%40%12%
15418

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
12%5%24323325%54%
1664
16th to endDay
9%422323335%59%
1920
February1st to 15thDay
7%5%23213235%60%
1750
16th to endDay
7%422323345%60%
1580
March1st to 15thDay
13%6%23213335%54%
1845
16th to endDay
12%5%23222346%56%
2112
April1st to 15thDay
10%424323346%56%
2126
16th to endDay
9%424223346%56%
2160
May1st to 15thDay
12%5%2442345%8%48%
2271
16th to endDay
13%5%24324446%46%
2430
June1st to 15thDay
6%312323449%58%
2340
16th to endDay
8%3235%35%47%8%47%
2340
July1st to 15thDay
8%4345%25%5%6%6%46%
2340
16th to endDay
6%2133245%6%9%53%
2354
August1st to 15thDay
321342445%9%58%
2160
16th to endDay
7%3245%35%6%7%8%46%
2292
September1st to 15thDay
10%5%25%5%45%6%6%7%39%
2030
16th to endDay
9%5%244345%46%49%
1837
October1st to 15thDay
10%41431345%5%56%
1815
16th to endDay
8%31221223466%
1861
November1st to 15thDay
10%313312446%57%
1583
16th to endDay
10%5%14212225%60%
1620
December1st to 15thDay
15%5%14323336%50%
1620
16th to endDay
12%6%34312346%52%
1728
January1st to 15thNight
11%5%24323245%55%
2284
16th to endNight
11%422322336%56%
2304
February1st to 15thNight
7%5%13213246%60%
2102
16th to endNight
8%312323346%60%
1894
March1st to 15thNight
10%5%12212346%58%
2114
16th to endNight
8%314313346%58%
2112
April1st to 15thNight
8%21332335%8%57%
1819
16th to endNight
6%323222236%63%
1800
May1st to 15thNight
8%424323446%55%
1676
16th to endNight
8%42442345%8%52%
1683
June1st to 15thNight
21111345%12%64%
1620
16th to endNight
42133345%5%10%55%
1620
July1st to 15thNight
5%21342445%9%55%
1620
16th to endNight
321221345%8%63%
1812
August1st to 15thNight
111221345%9%66%
1800
16th to endNight
6%21332447%11%52%
1910
September1st to 15thNight
431443446%8%52%
1929
16th to endNight
7%4145%1436%9%50%
1848
October1st to 15thNight
7%212313346%64%
1815
16th to endNight
5%31221233469%
1996
November1st to 15thNight
7%2221333466%
2275
16th to endNight
8%312212335%65%
2340
December1st to 15thNight
12%5%1322235%8%53%
2340
16th to endNight
10%5%23313336%55%
2496

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%5%24323235%54%
1664
16th to endDay
10%322323345%59%
1920
February1st to 15thDay
7%6%2322333460%
1750
16th to endDay
7%423312345%60%
1580
March1st to 15thDay
13%5%23312336%54%
1845
16th to endDay
12%422312336%56%
2110
April1st to 15thDay
10%324323337%55%
2126
16th to endDay
9%423314346%56%
2160
May1st to 15thDay
11%5%2441345%7%48%
2271
16th to endDay
13%6%24324446%46%
2430
June1st to 15thDay
5%31232345%8%59%
2340
16th to endDay
8%323435%46%8%47%
2340
July1st to 15thDay
8%435%5%25%5%5%6%46%
2340
16th to endDay
6%2133345%7%8%53%
2354
August1st to 15thDay
32134245%5%8%58%
2160
16th to endDay
7%3245%45%6%7%8%46%
2292
September1st to 15thDay
10%5%35%5%35%6%7%7%39%
2030
16th to endDay
8%5%25%434447%49%
1837
October1st to 15thDay
9%413323445%56%
1815
16th to endDay
7%213212335%65%
1861
November1st to 15thDay
9%413223347%56%
1583
16th to endDay
10%5%23322325%60%
1620
December1st to 15thDay
15%6%13323335%51%
1620
16th to endDay
12%6%24312346%52%
1728
January1st to 15thNight
10%5%24313245%56%
2284
16th to endNight
11%413312337%55%
2304
February1st to 15thNight
7%5%13312246%60%
2102
16th to endNight
8%312313346%60%
1894
March1st to 15thNight
10%5%13212346%58%
2114
16th to endNight
8%323323346%58%
2112
April1st to 15thNight
7%31332336%7%57%
1819
16th to endNight
6%413312236%63%
1800
May1st to 15thNight
8%424322347%55%
1676
16th to endNight
9%42432345%8%51%
1683
June1st to 15thNight
21121345%12%63%
1620
16th to endNight
5%2123245%5%10%55%
1620
July1st to 15thNight
5%21432446%10%54%
1620
16th to endNight
311221346%9%62%
1812
August1st to 15thNight
111222345%9%66%
1800
16th to endNight
5%21332347%12%51%
1910
September1st to 15thNight
431343446%9%52%
1929
16th to endNight
8%31442346%9%50%
1848
October1st to 15thNight
7%213212335%64%
1815
16th to endNight
5%31221333469%
1996
November1st to 15thNight
7%31231233466%
2275
16th to endNight
7%312212335%65%
2340
December1st to 15thNight
12%5%2221235%8%52%
2340
16th to endNight
10%5%23312345%55%
2496

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
33%2418%24%15%
1665
16th to endDay
27%38%15%28%17%
1920
February1st to 15thDay
28%26%17%22%21%
1751
16th to endDay
26%36%15%29%17%
1580
March1st to 15thDay
32%37%17%17%20%
1845
16th to endDay
31%38%18%20%18%
2112
April1st to 15thDay
30%47%16%21%19%
2126
16th to endDay
29%48%19%18%19%
2160
May1st to 15thDay
33%5%10%18%20%10%
2271
16th to endDay
37%5%9%20%18%7%
2434
June1st to 15thDay
23%5%13%27%22%8%
2340
16th to endDay
32%7%13%21%19%4
2340
July1st to 15thDay
34%6%14%25%14%2
2201
16th to endDay
22%9%21%29%16%
2208
August1st to 15thDay
21%7%16%32%20%1
2147
16th to endDay
31%9%17%23%14%2
2292
September1st to 15thDay
40%8%13%19%14%3
2030
16th to endDay
34%5%12%18%20%8%
1837
October1st to 15thDay
29%6%9%23%20%10%
1815
16th to endDay
22%36%13%31%22%
1861
November1st to 15thDay
30%38%23%19%14%
1583
16th to endDay
29%26%12%23%25%
1620
December1st to 15thDay
37%26%16%24%11%
1620
16th to endDay
34%37%17%25%11%
1728
January1st to 15thNight
32%25%16%23%19%
2284
16th to endNight
30%36%14%24%21%
2304
February1st to 15thNight
26%37%14%22%26%
2112
16th to endNight
24%37%16%27%19%
1894
March1st to 15thNight
27%39%16%19%22%
2114
16th to endNight
27%5%11%17%20%18%
2112
April1st to 15thNight
25%5%11%17%17%22%
1819
16th to endNight
25%39%23%19%18%
1800
May1st to 15thNight
30%5%11%20%19%13%
1677
16th to endNight
29%7%14%20%21%7%
1685
June1st to 15thNight
13%5%17%28%26%7%
1620
16th to endNight
23%7%15%26%21%6%
1620
July1st to 15thNight
24%8%15%28%20%3
1530
16th to endNight
15%8%20%33%20%1
1695
August1st to 15thNight
14%6%17%32%26%2
1789
16th to endNight
24%9%19%27%16%3
1910
September1st to 15thNight
26%8%17%24%17%5%
1929
16th to endNight
30%6%15%22%15%10%
1848
October1st to 15thNight
22%312%28%20%12%
1815
16th to endNight
18%37%14%30%24%
1996
November1st to 15thNight
22%36%23%26%16%
2275
16th to endNight
22%38%16%20%29%
2340
December1st to 15thNight
30%39%17%21%16%
2340
16th to endNight
30%36%16%24%17%
2496

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
12%432%37%13%
90
16th to endDay
8%13%34%29%14%
96
February1st to 15thDay
10%7%31%27%21%2
90
16th to endDay
9%8%46%28%6%
81
March1st to 15thDay
22%432%28%10%2
90
16th to endDay
6%5%34%42%9%2
96
April1st to 15thDay
8%11%49%26%3
245
16th to endDay
7%10%42%30%9%
270
May1st to 15thDay
16%6%42%28%4
408
16th to endDay
16%5%32%35%9%
517
June1st to 15thDay
6%120%55%14%1
495
16th to endDay
8%118%42%26%3
495
July1st to 15thDay
10%110%49%25%2
475
16th to endDay
5%6%41%39%6%
403
August1st to 15thDay
4243%37%11%
315
16th to endDay
6%18%43%31%8%
332
September1st to 15thDay
5%5%31%47%8%
185
16th to endDay
9%1428%41%15%
96
October1st to 15thDay
6%18%53%26%3
90
16th to endDay
15%315%39%22%3
96
November1st to 15thDay
23%6%26%27%13%2
90
16th to endDay
25%10%26%21%12%4
90
December1st to 15thDay
18%6%24%30%13%6%
90
16th to endDay
20%7%34%28%8%1
96
January1st to 15thNight
13%6%32%38%8%
857
16th to endNight
13%6%33%36%9%
768
February1st to 15thNight
11%8%36%33%8%
704
16th to endNight
11%9%49%27%2
632
March1st to 15thNight
14%6%44%29%5%
674
16th to endNight
8%11%49%27%2
576
April1st to 15thNight
7%8%57%23%2
539
16th to endNight
5%8%57%25%2
540
May1st to 15thNight
8%8%50%29%3
540
16th to endNight
8%5%42%35%7%
563
June1st to 15thNight
234%56%5%
540
16th to endNight
328%51%15%
540
July1st to 15thNight
6%14%57%18%1
510
16th to endNight
310%62%22%
564
August1st to 15thNight
2258%32%2
539
16th to endNight
5%8%54%29%2
573
September1st to 15thNight
5%7%51%32%3
540
16th to endNight
9%13%45%28%1
501
October1st to 15thNight
7%127%47%15%
495
16th to endNight
6%327%44%16%1
588
November1st to 15thNight
8%428%39%17%1
875
16th to endNight
9%5%30%38%14%1
900
December1st to 15thNight
15%5%27%40%10%
900
16th to endNight
13%7%34%36%6%
960
Page generated at 2017-09-19 06:32:26. Version ac04

Copyright 2017 A. Danko


Devils River State Natural Area Clear Sky Chart | Charts Home