Lyndon B. Johnson National Grasslands
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lyndon B. Johnson National Grasslands clear sky chart from 2005-11-06 to 2024-01-11.

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
47%
24042
30%
74218
19%
23986
58%
23986
39%
39791

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 10thNight
37%
948
33%
2458
12%
946
49%
946
43%
1393
January11th to 20thNight
35%
905
30%
2353
11%
905
47%
905
39%
1374
January21st to endNight
37%
990
35%
2574
13%
990
50%
990
39%
1501
February1st to 10thNight
30%
765
30%
2205
11%
765
45%
765
34%
1286
February11th to 20thNight
28%
704
25%
2098
9%
700
41%
700
31%
1227
February21st to endNight
21%
592
30%
1776
8%
592
39%
592
29%
1039
March1st to 10thNight
30%
566
27%
2006
13%
566
46%
566
26%
1137
March11th to 20thNight
31%
540
26%
1980
14%
540
46%
540
28%
1082
March21st to endNight
31%
594
26%
2178
14%
594
48%
594
31%
1144
April1st to 10thNight
27%
540
26%
1980
13%
540
46%
540
32%
1007
April11th to 20thNight
28%
533
27%
1859
15%
533
47%
533
32%
995
April21st to endNight
31%
540
30%
1620
15%
540
51%
540
37%
900
May1st to 10thNight
34%
540
28%
1620
15%
540
52%
540
35%
925
May11th to 20thNight
40%
531
21%
1594
15%
531
51%
531
34%
929
May21st to endNight
49%
583
24%
1745
18%
582
62%
582
39%
969
June1st to 10thNight
67%
540
23%
1620
21%
540
74%
540
46%
834
June11th to 20thNight
64%
540
27%
1620
26%
540
71%
540
52%
805
June21st to endNight
72%
540
29%
1620
29%
540
78%
540
54%
774
July1st to 10thNight
77%
525
23%
1575
25%
525
79%
525
45%
840
July11th to 20thNight
82%
522
34%
1566
36%
522
88%
522
63%
695
July21st to endNight
85%
591
34%
1673
39%
558
87%
558
56%
788
August1st to 10thNight
85%
537
37%
1601
40%
534
88%
534
62%
713
August11th to 20thNight
78%
534
36%
1600
40%
534
81%
534
48%
807
August21st to endNight
85%
594
30%
2043
37%
594
85%
594
48%
948
September1st to 10thNight
73%
540
26%
1980
31%
540
75%
540
38%
987
September11th to 20thNight
67%
540
25%
1980
28%
540
70%
540
31%
1098
September21st to endNight
73%
540
36%
1980
35%
540
79%
540
46%
889
October1st to 10thNight
64%
540
38%
1980
33%
540
73%
540
45%
898
October11th to 20thNight
50%
710
36%
2150
20%
710
61%
710
44%
1113
October21st to endNight
43%
792
34%
2376
19%
792
53%
792
40%
1268
November1st to 10thNight
47%
749
32%
2229
17%
749
59%
749
44%
1173
November11th to 20thNight
46%
950
31%
2470
15%
950
55%
950
47%
1336
November21st to endNight
34%
950
31%
2470
12%
950
47%
950
35%
1514
December1st to 10thNight
38%
950
34%
2470
14%
950
50%
950
41%
1431
December11th to 20thNight
34%
949
32%
2858
13%
948
45%
948
31%
1687
December21st to endNight
30%
1038
19%
4311
11%
1026
43%
1026
25%
2285

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
10%42443445%7%53%
74897
Night
9%424323447%58%
74824
TransparencyDay
30%5%9%24%23%8%
74622
Night
27%49%23%26%12%
74619
SeeingDay
11%7%24%29%22%7%
14039
Night
10%8%31%35%15%1
24053

By Month

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 10thDay
11%5%34423246%58%
1707
11th to 20thDay
12%5%23324345%57%
1620
21st to endDay
13%5%24333345%56%
1782
February1st to 10thDay
14%7%25%423346%51%
1768
11th to 20thDay
14%5%35%444345%49%
1749
21st to endDay
19%6%3332223453%
1480
March1st to 10thDay
17%5%1442345%7%48%
1952
11th to 20thDay
14%5%35%423345%52%
1980
21st to endDay
13%5%2432446%7%49%
2178
April1st to 10thDay
10%5%2442445%5%55%
1980
11th to 20thDay
12%5%25%43345%7%50%
2045
21st to endDay
11%4244345%46%51%
2340
May1st to 10thDay
12%5%24424447%51%
2340
11th to 20thDay
12%6%25%425%5%6%8%46%
2302
21st to endDay
11%6%35%6%35%6%7%9%40%
2531
June1st to 10thDay
5%3244346%7%9%53%
2340
11th to 20thDay
5%314435%5%7%9%55%
2340
21st to endDay
5%32334446%9%55%
2340
July1st to 10thDay
5%425%6%36%6%6%11%46%
2340
11th to 20thDay
4212435%5%5%8%62%
2340
21st to endDay
3223445%6%8%10%52%
2546
August1st to 10thDay
22135%35%5%5%8%60%
2328
11th to 20thDay
6%4246%46%5%6%9%49%
2301
21st to endDay
5%313335%6%7%10%54%
2306
September1st to 10thDay
9%423435%447%56%
1980
11th to 20thDay
11%5%25%5%46%5%6%6%46%
1980
21st to endDay
7%31442345%7%58%
1980
October1st to 10thDay
5%32343435%7%61%
1971
11th to 20thDay
10%323322345%64%
1800
21st to endDay
14%5%1332332362%
1980
November1st to 10thDay
11%5%23323335%60%
1845
11th to 20thDay
6%413333346%65%
1710
21st to endDay
14%5%2332334457%
1710
December1st to 10thDay
11%6%15%42345%6%52%
1710
11th to 20thDay
12%7%35%5%33336%50%
2161
21st to endDay
17%5%24324345%51%
3135
January1st to 10thNight
9%42432335%7%59%
2458
11th to 20thNight
11%5%23422235%60%
2353
21st to endNight
10%434324345%59%
2574
February1st to 10thNight
12%5%24423345%56%
2205
11th to 20thNight
13%5%34324346%53%
2098
21st to endNight
15%5%24322335%55%
1776
March1st to 10thNight
12%5%25%4245%5%8%48%
2006
11th to 20thNight
13%5%24323347%52%
1980
21st to endNight
10%424424347%56%
2178
April1st to 10thNight
8%4234245%6%8%54%
1980
11th to 20thNight
10%5%35%324347%54%
1859
21st to endNight
10%41442445%7%56%
1620
May1st to 10thNight
9%5%3442445%7%54%
1620
11th to 20thNight
9%5%245%34448%51%
1593
21st to endNight
8%3243245%6%10%53%
1745
June1st to 10thNight
32234245%7%10%59%
1620
11th to 20thNight
31133245%6%10%63%
1620
21st to endNight
321322336%9%66%
1620
July1st to 10thNight
43233345%6%11%55%
1620
11th to 20thNight
2112213349%71%
1620
21st to endNight
111233445%11%64%
1772
August1st to 10thNight
221221336%10%69%
1611
11th to 20thNight
5%3133235%6%10%59%
1600
21st to endNight
32233245%5%10%60%
2043
September1st to 10thNight
6%415%5%23348%59%
1980
11th to 20thNight
9%5%25%5%4445%7%50%
1980
21st to endNight
6%2122245%5%6%64%
1980
October1st to 10thNight
6%313323448%64%
1980
11th to 20thNight
10%32331233465%
2150
21st to endNight
14%41322223464%
2376
November1st to 10thNight
9%313313335%64%
2229
11th to 20thNight
5%41332335%5%64%
2470
21st to endNight
14%5%24333445%55%
2470
December1st to 10thNight
11%5%24323346%58%
2470
11th to 20thNight
11%6%24424445%53%
3036
21st to endNight
15%6%24323235%55%
4532

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 10thDay
31%37%20%31%9%
1708
11th to 20thDay
32%36%23%28%8%
1620
21st to endDay
32%3421%28%12%
1782
February1st to 10thDay
36%46%21%24%9%
1768
11th to 20thDay
39%36%21%21%10%
1759
21st to endDay
38%2315%26%16%
1480
March1st to 10thDay
37%46%19%21%13%
1952
11th to 20thDay
36%5%9%20%24%7%
1980
21st to endDay
34%5%10%22%21%8%
2178
April1st to 10thDay
33%49%24%18%12%
1980
11th to 20thDay
34%5%9%20%20%12%
2045
21st to endDay
33%5%9%24%24%5%
2340
May1st to 10thDay
34%5%10%24%20%7%
2340
11th to 20thDay
36%6%12%25%20%2
2306
21st to endDay
39%8%14%21%16%2
2531
June1st to 10thDay
27%6%17%29%18%3
2340
11th to 20thDay
25%8%12%29%22%5%
2340
21st to endDay
25%6%11%25%27%6%
2340
July1st to 10thDay
30%9%16%28%16%1
2276
11th to 20thDay
19%6%12%32%26%5%
2271
21st to endDay
23%7%15%34%20%1
2405
August1st to 10thDay
20%6%14%31%27%3
2314
11th to 20thDay
31%7%13%26%21%3
2301
21st to endDay
22%6%12%32%22%5%
2306
September1st to 10thDay
29%6%9%21%25%10%
1980
11th to 20thDay
37%8%9%18%21%7%
1980
21st to endDay
25%5%7%24%27%12%
1980
October1st to 10thDay
23%5%11%22%24%16%
1971
11th to 20thDay
24%36%18%30%18%
1800
21st to endDay
29%36%20%27%16%
1980
November1st to 10thDay
28%38%22%27%12%
1845
11th to 20thDay
21%49%22%31%13%
1710
21st to endDay
32%35%21%27%12%
1710
December1st to 10thDay
33%47%25%24%7%
1710
11th to 20thDay
39%36%16%26%11%
2159
21st to endDay
36%4423%24%9%
3135
January1st to 10thNight
27%36%21%31%12%
2458
11th to 20thNight
29%37%19%31%11%
2353
21st to endNight
30%3419%29%16%
2574
February1st to 10thNight
32%46%21%23%13%
2205
11th to 20thNight
34%47%18%26%11%
2098
21st to endNight
35%35%16%21%19%
1776
March1st to 10thNight
34%6%6%16%23%16%
2006
11th to 20thNight
33%48%20%24%10%
1980
21st to endNight
29%5%11%22%25%8%
2178
April1st to 10thNight
27%5%12%21%21%15%
1980
11th to 20thNight
30%5%9%20%20%15%
1859
21st to endNight
28%5%11%24%26%6%
1620
May1st to 10thNight
30%5%10%22%23%9%
1620
11th to 20thNight
32%6%16%23%20%4
1594
21st to endNight
26%7%17%27%21%2
1746
June1st to 10thNight
19%8%16%33%20%5%
1620
11th to 20thNight
17%7%14%33%23%8%
1620
21st to endNight
16%5%13%27%30%8%
1620
July1st to 10thNight
21%8%16%32%21%2
1575
11th to 20thNight
12%410%35%31%8%
1566
21st to endNight
15%5%14%37%26%3
1673
August1st to 10thNight
12%410%34%33%6%
1601
11th to 20thNight
21%5%13%30%26%6%
1600
21st to endNight
19%5%12%31%27%6%
2043
September1st to 10thNight
25%5%9%22%28%10%
1980
11th to 20thNight
33%5%11%19%21%11%
1980
21st to endNight
20%49%22%29%16%
1980
October1st to 10thNight
20%410%24%24%17%
1980
11th to 20thNight
25%38%14%29%22%
2150
21st to endNight
28%35%19%27%19%
2376
November1st to 10thNight
25%47%21%27%16%
2229
11th to 20thNight
22%47%22%30%15%
2470
21st to endNight
33%45%16%28%13%
2470
December1st to 10thNight
28%37%23%26%12%
2470
11th to 20thNight
34%35%16%29%13%
3037
21st to endNight
33%35%19%28%12%
4532

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 10thDay
17%12%38%27%6%
270
11th to 20thDay
17%15%32%26%7%3
240
21st to endDay
19%12%41%20%8%1
264
February1st to 10thDay
22%13%36%24%5%
240
11th to 20thDay
21%15%43%17%4
240
21st to endDay
28%17%38%13%4
198
March1st to 10thDay
20%20%33%20%7%
240
11th to 20thDay
20%21%36%17%6%
240
21st to endDay
14%18%46%16%5%1
264
April1st to 10thDay
14%16%38%23%8%2
240
11th to 20thDay
13%15%43%22%7%
323
21st to endDay
14%16%40%21%8%1
600
May1st to 10thDay
13%11%37%30%8%1
603
11th to 20thDay
15%8%31%30%14%2
625
21st to endDay
13%8%29%30%16%4
679
June1st to 10thDay
5%317%42%27%7%
630
11th to 20thDay
6%219%41%26%6%
630
21st to endDay
5%213%37%34%9%
630
July1st to 10thDay
6%17%36%36%14%
621
11th to 20thDay
316%30%47%13%
618
21st to endDay
216%30%45%17%
684
August1st to 10thDay
316%35%41%14%
626
11th to 20thDay
8%27%33%40%11%
615
21st to endDay
5%16%32%36%20%
425
September1st to 10thDay
7%421%46%21%
270
11th to 20thDay
5%29%25%39%21%
270
21st to endDay
13%29%29%33%14%
270
October1st to 10thDay
4220%33%31%10%
270
11th to 20thDay
10%9%29%30%20%1
270
21st to endDay
24%8%25%27%13%3
297
November1st to 10thDay
15%7%35%26%14%3
270
11th to 20thDay
11%10%30%34%9%4
270
21st to endDay
18%12%37%22%10%1
270
December1st to 10thDay
13%11%37%26%11%2
270
11th to 20thDay
14%11%41%26%8%
270
21st to endDay
19%11%38%23%9%
297
January1st to 10thNight
12%10%38%31%8%
950
11th to 20thNight
13%13%34%33%7%
905
21st to endNight
12%11%36%33%7%
990
February1st to 10thNight
14%12%40%29%4
765
11th to 20thNight
17%12%40%28%3
704
21st to endNight
18%16%43%21%2
592
March1st to 10thNight
14%14%39%29%4
566
11th to 20thNight
15%11%41%28%5%
540
21st to endNight
11%13%43%28%5%
594
April1st to 10thNight
10%13%46%26%4
540
11th to 20thNight
11%14%44%26%5%
533
21st to endNight
11%13%43%26%6%1
540
May1st to 10thNight
9%11%42%31%6%1
540
11th to 20thNight
10%5%41%31%12%2
531
21st to endNight
7%434%38%14%2
584
June1st to 10thNight
4122%49%21%3
540
11th to 20thNight
3128%52%16%
540
21st to endNight
2120%46%28%3
540
July1st to 10thNight
4210%46%34%4
525
11th to 20thNight
310%47%38%3
522
21st to endNight
27%47%41%3
591
August1st to 10thNight
217%51%35%3
537
11th to 20thNight
7%17%45%37%4
534
21st to endNight
316%46%40%5%
594
September1st to 10thNight
6%112%40%39%3
540
11th to 20thNight
10%111%42%32%3
540
21st to endNight
7%116%45%29%2
540
October1st to 10thNight
8%223%41%24%2
540
11th to 20thNight
11%6%29%38%15%1
710
21st to endNight
16%11%29%32%12%1
792
November1st to 10thNight
11%435%35%15%1
749
11th to 20thNight
8%10%34%36%11%1
950
21st to endNight
17%10%36%27%9%
950
December1st to 10thNight
13%10%36%35%6%
950
11th to 20thNight
17%10%36%31%6%
950
21st to endNight
16%11%39%29%6%
1045
Page generated at 2024-01-08 10:14:15. Version ac07

Copyright 2024 Attilla Danko


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