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 2017-03-22.

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
74%
15505
40%
45274
32%
15466
81%
15466
64%
19668

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%
717
34%
2327
29%
716
72%
716
49%
1052
January16th to endNight
60%
768
40%
2355
29%
768
74%
768
49%
1105
February1st to 15thNight
64%
698
39%
2107
31%
697
77%
697
55%
972
February16th to endNight
62%
632
39%
1895
36%
632
72%
632
54%
888
March1st to 15thNight
65%
720
37%
2142
32%
720
76%
720
59%
941
March16th to endNight
69%
732
38%
1973
28%
732
78%
732
63%
916
April1st to 15thNight
61%
659
40%
1649
21%
659
71%
659
63%
812
April16th to endNight
69%
655
41%
1645
21%
655
76%
655
74%
739
May1st to 15thNight
72%
494
46%
1484
31%
494
79%
494
78%
554
May16th to endNight
77%
514
38%
1541
30%
513
81%
513
78%
589
June1st to 15thNight
81%
495
37%
1485
31%
495
83%
495
76%
578
June16th to endNight
85%
495
35%
1485
32%
495
86%
495
83%
558
July1st to 15thNight
88%
465
34%
1395
31%
465
88%
465
70%
578
July16th to endNight
87%
522
36%
1467
30%
489
88%
489
63%
641
August1st to 15thNight
92%
651
41%
1635
27%
648
93%
648
79%
740
August16th to endNight
91%
700
42%
1750
29%
700
92%
700
76%
812
September1st to 15thNight
92%
660
42%
1730
34%
660
93%
660
77%
769
September16th to endNight
89%
656
48%
1815
43%
656
93%
656
84%
725
October1st to 15thNight
76%
660
45%
1815
35%
660
85%
660
71%
788
October16th to endNight
79%
704
45%
2128
41%
704
86%
704
70%
858
November1st to 15thNight
75%
700
40%
2275
36%
700
87%
700
67%
876
November16th to endNight
74%
720
43%
2340
40%
720
84%
720
61%
953
December1st to 15thNight
67%
720
36%
2340
31%
720
78%
720
50%
1059
December16th to endNight
58%
768
36%
2496
29%
768
71%
768
44%
1165

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%74%
45606
Night
111212235%75%
45474
TransparencyDay
12%2314%28%39%
45301
Night
11%2414%29%36%
45280
SeeingDay
313%27%33%17%4
5120
Night
1414%32%33%12%
15516

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
2312313346%66%
1611
16th to endDay
23331435%6%65%
1866
February1st to 15thDay
1213213337%67%
1751
16th to endDay
111232446%7%63%
1579
March1st to 15thDay
111113447%72%
1818
16th to endDay
12313336%72%
2045
April1st to 15thDay
122212346%70%
1969
16th to endDay
11111235%81%
1983
May1st to 15thDay
1111125%82%
2136
16th to endDay
111123383%
2221
June1st to 15thDay
11113384%
2145
16th to endDay
11111287%
2145
July1st to 15thDay
2112212345%72%
2145
16th to endDay
221222345%5%67%
2285
August1st to 15thDay
1221233476%
1984
16th to endDay
211212235%76%
2100
September1st to 15thDay
11111233477%
1900
16th to endDay
111111286%
1815
October1st to 15thDay
11111223479%
1815
16th to endDay
121123480%
1741
November1st to 15thDay
111212325%77%
1584
16th to endDay
2111112346%71%
1620
December1st to 15thDay
221233235%9%61%
1620
16th to endDay
2214314347%63%
1728
January1st to 15thNight
1213323347%65%
2327
16th to endNight
3213313435%66%
2355
February1st to 15thNight
1212214245%70%
2101
16th to endNight
12122145%6%7%63%
1895
March1st to 15thNight
1112213348%70%
2142
16th to endNight
12213247%71%
1973
April1st to 15thNight
22213235%75%
1649
16th to endNight
11122384%
1645
May1st to 15thNight
123484%
1484
16th to endNight
1113484%
1540
June1st to 15thNight
1132286%
1485
16th to endNight
111288%
1485
July1st to 15thNight
1112212235%76%
1485
16th to endNight
122212345%73%
1575
August1st to 15thNight
111223481%
1644
16th to endNight
1111123380%
1750
September1st to 15thNight
111122482%
1730
16th to endNight
111290%
1815
October1st to 15thNight
11121123479%
1815
16th to endNight
111112481%
2128
November1st to 15thNight
11111223479%
2275
16th to endNight
211212335%75%
2340
December1st to 15thNight
2212323448%64%
2340
16th to endNight
3313223346%65%
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
17%35%18%31%24%
1612
16th to endDay
19%2419%30%23%
1866
February1st to 15thDay
16%25%18%29%27%
1751
16th to endDay
18%35%20%33%18%
1579
March1st to 15thDay
10%2320%33%28%
1818
16th to endDay
12%3423%32%24%
2045
April1st to 15thDay
15%1316%38%25%
1969
16th to endDay
7%1217%34%37%
1983
May1st to 15thDay
7%1112%34%41%
2136
16th to endDay
6%2213%34%40%
2224
June1st to 15thDay
6%118%20%61%
2145
16th to endDay
7%1311%74%
2145
July1st to 15thDay
14%328%20%51%
2006
16th to endDay
15%46%14%22%36%
2130
August1st to 15thDay
9%2210%21%53%
1969
16th to endDay
11%239%26%46%
2100
September1st to 15thDay
10%337%21%52%
1900
16th to endDay
8%115%26%58%
1815
October1st to 15thDay
9%3210%32%42%
1815
16th to endDay
8%1310%27%47%
1741
November1st to 15thDay
11%1314%33%34%
1584
16th to endDay
13%1415%31%33%
1620
December1st to 15thDay
18%37%22%25%22%
1620
16th to endDay
19%38%25%25%17%
1728
January1st to 15thNight
17%35%17%28%27%
2327
16th to endNight
18%35%19%25%27%
2355
February1st to 15thNight
16%2419%28%28%
2112
16th to endNight
16%35%22%30%21%
1895
March1st to 15thNight
13%2418%33%27%
2142
16th to endNight
11%36%19%35%23%
1973
April1st to 15thNight
13%25%20%33%25%
1649
16th to endNight
6%2216%38%33%
1645
May1st to 15thNight
41117%36%38%
1485
16th to endNight
5%1315%43%30%
1541
June1st to 15thNight
6%2111%20%58%
1485
16th to endNight
5%5%15%72%
1485
July1st to 15thNight
10%137%20%57%
1395
16th to endNight
12%3416%27%35%
1467
August1st to 15thNight
6%2111%25%52%
1635
16th to endNight
8%228%30%46%
1750
September1st to 15thNight
7%248%22%53%
1730
16th to endNight
416%27%60%
1815
October1st to 15thNight
9%2211%35%38%
1815
16th to endNight
8%148%26%49%
2128
November1st to 15thNight
9%1312%37%34%
2275
16th to endNight
12%2317%30%34%
2340
December1st to 15thNight
17%38%17%27%25%
2340
16th to endNight
19%310%20%27%19%
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
10%13%25%42%8%
90
16th to endDay
5%25%27%28%10%2
234
February1st to 15thDay
217%35%27%13%3
266
16th to endDay
5%30%25%23%13%
238
March1st to 15thDay
322%27%27%15%3
270
16th to endDay
316%38%27%12%2
250
April1st to 15thDay
10%23%32%20%10%2
209
16th to endDay
326%35%24%8%1
210
May1st to 15thDay
317%32%33%9%3
228
16th to endDay
115%31%35%9%6%
266
June1st to 15thDay
210%34%30%16%4
255
16th to endDay
36%29%33%18%8%
255
July1st to 15thDay
19%50%19%9%
245
16th to endDay
1218%45%21%11%
271
August1st to 15thDay
321%42%23%8%
255
16th to endDay
2119%40%25%11%
268
September1st to 15thDay
2321%48%20%2
255
16th to endDay
310%20%35%23%5%
255
October1st to 15thDay
112%34%35%14%1
255
16th to endDay
210%24%30%28%2
179
November1st to 15thDay
20%13%25%32%8%
90
16th to endDay
321%24%31%18%1
90
December1st to 15thDay
415%16%31%30%2
90
16th to endDay
317%29%32%17%
96
January1st to 15thNight
28%20%34%23%11%
720
16th to endNight
47%20%32%25%8%
768
February1st to 15thNight
27%19%36%25%8%
704
16th to endNight
26%24%38%20%7%
632
March1st to 15thNight
28%19%35%26%7%
720
16th to endNight
16%18%37%26%9%
732
April1st to 15thNight
18%24%33%25%6%
659
16th to endNight
8%19%34%25%11%
655
May1st to 15thNight
6%18%34%32%7%
495
16th to endNight
316%38%33%7%
515
June1st to 15thNight
114%41%35%6%
495
16th to endNight
11%37%42%7%
495
July1st to 15thNight
2330%50%12%
465
16th to endNight
2328%51%13%
522
August1st to 15thNight
1226%50%19%
651
16th to endNight
2116%49%28%
700
September1st to 15thNight
225%50%20%
660
16th to endNight
116%28%43%18%
656
October1st to 15thNight
1215%33%35%11%
660
16th to endNight
1410%29%36%17%
704
November1st to 15thNight
5%15%31%33%12%
700
16th to endNight
25%13%33%29%15%
720
December1st to 15thNight
25%19%34%28%9%
720
16th to endNight
412%20%31%24%6%
768
Page generated at 2017-03-23 04:36:11. Version ac04

Copyright 2017 A. Danko


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