Yucca Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yucca Valley clear sky chart from 2005-11-05 to 2018-11-30.

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
75%
17765
40%
51797
32%
17726
82%
17726
65%
22385

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
62%
777
34%
2522
30%
776
72%
776
48%
1157
January16th to endNight
61%
832
41%
2551
30%
832
75%
832
51%
1188
February1st to 15thNight
65%
758
39%
2287
31%
757
78%
757
55%
1041
February16th to endNight
62%
684
41%
2051
36%
684
73%
684
55%
946
March1st to 15thNight
65%
780
36%
2321
31%
780
76%
780
58%
1024
March16th to endNight
68%
832
39%
2240
28%
832
78%
832
63%
1039
April1st to 15thNight
62%
779
40%
1949
20%
779
72%
779
63%
956
April16th to endNight
68%
766
42%
1924
21%
766
76%
766
73%
868
May1st to 15thNight
73%
584
44%
1754
31%
584
79%
584
76%
667
May16th to endNight
77%
610
40%
1829
31%
609
81%
609
79%
694
June1st to 15thNight
82%
585
37%
1755
31%
585
84%
585
79%
670
June16th to endNight
86%
585
37%
1755
33%
585
87%
585
84%
657
July1st to 15thNight
89%
555
34%
1665
30%
555
89%
555
72%
674
July16th to endNight
88%
612
36%
1737
30%
579
88%
579
63%
762
August1st to 15thNight
93%
758
40%
1904
26%
755
93%
755
80%
858
August16th to endNight
92%
828
43%
2070
30%
828
92%
828
77%
948
September1st to 15thNight
92%
780
43%
2044
35%
780
93%
780
78%
902
September16th to endNight
89%
776
49%
2145
44%
776
93%
776
85%
849
October1st to 15thNight
77%
780
46%
2145
36%
780
86%
780
73%
919
October16th to endNight
80%
832
45%
2515
42%
832
87%
832
70%
1006
November1st to 15thNight
76%
820
42%
2665
38%
820
86%
820
66%
1038
November16th to endNight
74%
840
42%
2730
40%
840
84%
840
59%
1140
December1st to 15thNight
66%
780
36%
2535
31%
780
77%
780
51%
1132
December16th to endNight
59%
832
38%
2704
30%
832
72%
832
45%
1250

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
112212335%75%
52500
Night
111212235%76%
51997
TransparencyDay
11%2313%28%40%
52195
Night
11%2414%30%37%
51803
SeeingDay
212%25%33%19%6%
7429
Night
1414%32%34%12%
17776

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
2312323346%66%
1746
16th to endDay
223314347%65%
2022
February1st to 15thDay
1213213337%69%
1901
16th to endDay
11232446%7%64%
1709
March1st to 15thDay
111113447%71%
1969
16th to endDay
2313347%72%
2333
April1st to 15thDay
122212346%71%
2329
16th to endDay
1111236%79%
2308
May1st to 15thDay
1111125%82%
2526
16th to endDay
111122383%
2637
June1st to 15thDay
11112385%
2535
16th to endDay
1111288%
2535
July1st to 15thDay
2112213345%70%
2535
16th to endDay
211222346%6%65%
2675
August1st to 15thDay
111212335%76%
2297
16th to endDay
111212235%76%
2484
September1st to 15thDay
1111233477%
2246
16th to endDay
111111287%
2145
October1st to 15thDay
1111222480%
2145
16th to endDay
121123480%
2058
November1st to 15thDay
1112212325%75%
1854
16th to endDay
111222235%7%69%
1884
December1st to 15thDay
121233235%9%63%
1755
16th to endDay
2214314347%64%
1872
January1st to 15thNight
1223323448%64%
2522
16th to endNight
2213313446%66%
2551
February1st to 15thNight
1212213345%71%
2281
16th to endNight
12112135%6%7%64%
2051
March1st to 15thNight
11221345%8%69%
2321
16th to endNight
12213247%71%
2240
April1st to 15thNight
22212236%74%
1949
16th to endNight
11123482%
1924
May1st to 15thNight
111123484%
1754
16th to endNight
113485%
1828
June1st to 15thNight
1121287%
1755
16th to endNight
111289%
1755
July1st to 15thNight
111112235%77%
1755
16th to endNight
111212445%72%
1845
August1st to 15thNight
11123481%
1913
16th to endNight
1111123381%
2070
September1st to 15thNight
111122483%
2044
16th to endNight
111191%
2145
October1st to 15thNight
11111122481%
2145
16th to endNight
111112482%
2515
November1st to 15thNight
11111223478%
2665
16th to endNight
212212336%72%
2730
December1st to 15thNight
2212323348%65%
2535
16th to endNight
2313223346%64%
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
18%35%19%30%22%
1747
16th to endDay
18%2420%31%22%
2022
February1st to 15thDay
15%2417%30%29%
1901
16th to endDay
17%35%19%33%20%
1709
March1st to 15thDay
11%3321%32%27%
1969
16th to endDay
11%3422%33%23%
2333
April1st to 15thDay
14%1315%36%27%
2329
16th to endDay
7%1216%33%37%
2308
May1st to 15thDay
7%1111%35%41%
2526
16th to endDay
7%1212%34%41%
2640
June1st to 15thDay
6%117%20%62%
2535
16th to endDay
6%310%77%
2535
July1st to 15thDay
14%329%18%51%
2396
16th to endDay
16%46%15%22%33%
2520
August1st to 15thDay
10%2210%21%53%
2282
16th to endDay
10%239%26%46%
2484
September1st to 15thDay
10%337%21%53%
2246
16th to endDay
7%11428%57%
2145
October1st to 15thDay
8%229%31%44%
2145
16th to endDay
8%139%28%48%
2058
November1st to 15thDay
12%1314%33%34%
1854
16th to endDay
13%1416%31%31%
1884
December1st to 15thDay
17%26%21%25%26%
1755
16th to endDay
19%37%23%26%19%
1872
January1st to 15thNight
18%35%19%28%24%
2522
16th to endNight
17%35%19%26%26%
2551
February1st to 15thNight
15%2418%28%30%
2292
16th to endNight
15%3421%32%22%
2051
March1st to 15thNight
13%25%19%33%25%
2321
16th to endNight
11%26%19%36%22%
2240
April1st to 15thNight
12%25%19%33%26%
1949
16th to endNight
6%2215%39%33%
1924
May1st to 15thNight
5%1116%37%37%
1755
16th to endNight
5%1214%41%34%
1829
June1st to 15thNight
5%2110%20%60%
1755
16th to endNight
5%5%13%75%
1755
July1st to 15thNight
9%138%19%57%
1665
16th to endNight
12%35%19%26%33%
1737
August1st to 15thNight
6%2110%27%52%
1904
16th to endNight
8%129%30%47%
2070
September1st to 15thNight
6%248%22%54%
2044
16th to endNight
315%28%60%
2145
October1st to 15thNight
8%1211%34%41%
2145
16th to endNight
8%238%27%50%
2515
November1st to 15thNight
10%1312%38%33%
2665
16th to endNight
12%2417%31%31%
2730
December1st to 15thNight
16%37%16%27%28%
2535
16th to endNight
19%39%18%28%20%
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
10%10%20%37%18%2
135
16th to endDay
422%26%28%13%4
294
February1st to 15thDay
216%33%27%14%6%
326
16th to endDay
5%29%24%25%14%
290
March1st to 15thDay
323%26%28%14%3
330
16th to endDay
219%36%27%11%2
352
April1st to 15thDay
6%21%30%21%16%3
329
16th to endDay
227%30%25%11%2
318
May1st to 15thDay
315%30%31%12%6%
348
16th to endDay
114%31%32%12%7%
394
June1st to 15thDay
29%29%31%17%9%
375
16th to endDay
25%24%32%22%12%
375
July1st to 15thDay
215%44%22%14%
365
16th to endDay
2115%42%23%14%
391
August1st to 15thDay
1218%40%25%10%
359
16th to endDay
1118%39%27%12%
396
September1st to 15thDay
1321%46%23%2
375
16th to endDay
29%23%33%26%5%
375
October1st to 15thDay
113%33%35%15%1
375
16th to endDay
29%21%28%31%6%
290
November1st to 15thDay
114%17%30%30%6%
180
16th to endDay
115%20%29%25%7%
178
December1st to 15thDay
218%17%28%30%2
135
16th to endDay
315%20%27%27%5%
144
January1st to 15thNight
27%19%35%24%11%
780
16th to endNight
46%20%32%27%8%
832
February1st to 15thNight
27%18%35%26%9%
764
16th to endNight
26%25%37%21%6%
684
March1st to 15thNight
28%19%36%26%7%
780
16th to endNight
17%18%36%26%9%
832
April1st to 15thNight
18%23%33%26%6%
779
16th to endNight
18%19%34%25%10%
766
May1st to 15thNight
6%17%35%32%7%
585
16th to endNight
217%38%33%7%
611
June1st to 15thNight
113%39%37%7%
585
16th to endNight
9%35%44%9%
585
July1st to 15thNight
1328%50%14%
555
16th to endNight
2328%50%14%
612
August1st to 15thNight
1225%50%21%
758
16th to endNight
2117%48%28%
828
September1st to 15thNight
226%50%19%
780
16th to endNight
16%29%43%18%
776
October1st to 15thNight
1315%35%34%9%
780
16th to endNight
1410%28%37%17%
832
November1st to 15thNight
5%14%34%34%11%
820
16th to endNight
25%13%32%31%14%
840
December1st to 15thNight
26%18%33%28%9%
780
16th to endNight
412%19%30%26%7%
832
Page generated at 2018-12-01 08:35:34. Version ac04

Copyright 2018 A. Danko


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