This page made possible by the sponsorship of: Riverside Astronomical Society.

Landers
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Landers clear sky chart from 2005-11-06 to 2024-01-16.

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
72%
24771
40%
74440
31%
24725
81%
24725
65%
31525

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
62%
758
35%
2457
27%
756
74%
756
49%
1101
January11th to 20thNight
65%
740
39%
2405
31%
740
78%
740
52%
1058
January21st to endNight
55%
792
43%
2376
28%
792
73%
792
50%
1121
February1st to 10thNight
60%
720
40%
2160
29%
720
75%
720
55%
976
February11th to 20thNight
59%
700
40%
2098
29%
700
75%
700
56%
943
February21st to endNight
56%
592
40%
1776
33%
592
71%
592
57%
771
March1st to 10thNight
55%
720
35%
2160
25%
720
72%
720
52%
996
March11th to 20thNight
62%
720
38%
2043
29%
720
74%
720
63%
902
March21st to endNight
57%
792
39%
2116
21%
792
72%
792
60%
987
April1st to 10thNight
56%
720
39%
1800
18%
720
68%
720
61%
895
April11th to 20thNight
58%
711
42%
1779
18%
711
71%
711
68%
830
April21st to endNight
63%
705
45%
1785
21%
705
74%
705
76%
779
May1st to 10thNight
66%
540
44%
1620
28%
540
74%
540
78%
606
May11th to 20thNight
70%
531
44%
1595
29%
531
78%
531
77%
605
May21st to endNight
68%
582
41%
1746
28%
582
76%
582
80%
646
June1st to 10thNight
79%
540
38%
1620
30%
540
83%
540
80%
608
June11th to 20thNight
78%
540
39%
1620
32%
540
82%
540
84%
594
June21st to endNight
80%
540
37%
1620
31%
540
84%
540
79%
624
July1st to 10thNight
92%
525
37%
1575
33%
525
92%
525
81%
594
July11th to 20thNight
88%
522
35%
1566
31%
522
88%
522
67%
664
July21st to endNight
89%
591
38%
1674
31%
558
89%
558
61%
749
August1st to 10thNight
91%
691
38%
1756
25%
688
92%
688
78%
792
August11th to 20thNight
94%
712
42%
1780
27%
712
94%
712
81%
798
August21st to endNight
91%
792
45%
1980
32%
792
91%
792
80%
896
September1st to 10thNight
88%
720
42%
1840
32%
720
90%
720
76%
838
September11th to 20thNight
90%
720
48%
1980
42%
720
94%
720
89%
767
September21st to endNight
85%
720
48%
1980
40%
720
92%
720
86%
789
October1st to 10thNight
77%
720
44%
1980
34%
720
86%
720
75%
841
October11th to 20thNight
82%
720
51%
1980
42%
720
89%
720
80%
804
October21st to endNight
78%
792
45%
2497
41%
792
88%
792
75%
923
November1st to 10thNight
75%
740
42%
2405
38%
740
87%
740
72%
899
November11th to 20thNight
78%
760
44%
2470
41%
760
88%
760
69%
948
November21st to endNight
69%
760
41%
2470
35%
760
80%
760
58%
1038
December1st to 10thNight
67%
760
38%
2470
30%
760
78%
760
53%
1090
December11th to 20thNight
64%
759
37%
2894
28%
758
76%
758
43%
1269
December21st to endNight
56%
824
24%
4367
29%
817
69%
817
32%
1784

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
2112212346%77%
74888
Night
1112212346%78%
74947
TransparencyDay
11%35%14%27%41%
74615
Night
10%36%14%28%39%
74742
SeeingDay
410%24%34%21%6%
14416
Night
25%19%36%31%7%
24792

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 10thDay
321332335%7%69%
1708
11th to 20thDay
431221235%7%72%
1665
21st to endDay
2213323346%70%
1978
February1st to 10thDay
2212213346%74%
1800
11th to 20thDay
1112223346%73%
1750
21st to endDay
1212313346%74%
1480
March1st to 10thDay
221122446%9%69%
1800
11th to 20thDay
2212222447%72%
1916
21st to endDay
11221235%6%77%
2236
April1st to 10thDay
2222213236%75%
2160
11th to 20thDay
111212235%83%
2129
21st to endDay
1111111236%82%
2173
May1st to 10thDay
111111235%82%
2340
11th to 20thDay
11111213485%
2301
21st to endDay
11111232484%
2530
June1st to 10thDay
1111112235%84%
2340
11th to 20thDay
111112390%
2340
21st to endDay
111111222385%
2340
July1st to 10thDay
2112222245%79%
2340
11th to 20thDay
3113223346%73%
2340
21st to endDay
2213435%5%6%7%62%
2545
August1st to 10thDay
2112212345%77%
2168
11th to 20thDay
11122445%6%75%
2122
21st to endDay
211212346%78%
2376
September1st to 10thDay
31221234477%
2118
11th to 20thDay
11111122290%
1980
21st to endDay
2121222385%
1980
October1st to 10thDay
111221233481%
1980
11th to 20thDay
1121122386%
1980
21st to endDay
11111113486%
1854
November1st to 10thDay
111213235%81%
1674
11th to 20thDay
1111212346%77%
1710
21st to endDay
2112213346%75%
1710
December1st to 10thDay
32223243410%66%
1710
11th to 20thDay
231343345%10%62%
2169
21st to endDay
5%3133245%6%9%59%
3146
January1st to 10thNight
121332445%8%67%
2457
11th to 20thNight
22232345%6%72%
2405
21st to endNight
331332335%6%70%
2376
February1st to 10thNight
2212322336%74%
2160
11th to 20thNight
3212222445%73%
2098
21st to endNight
111221235%8%73%
1776
March1st to 10thNight
221232345%8%69%
2160
11th to 20thNight
111221235%7%73%
2043
21st to endNight
112223346%77%
2116
April1st to 10thNight
1112323346%75%
1800
11th to 20thNight
11111233482%
1779
21st to endNight
111111137%84%
1785
May1st to 10thNight
11112236%84%
1620
11th to 20thNight
1113225%85%
1594
21st to endNight
1111112489%
1746
June1st to 10thNight
11223487%
1620
11th to 20thNight
111122389%
1620
21st to endNight
1111122388%
1620
July1st to 10thNight
1111123485%
1620
11th to 20thNight
1112223346%76%
1620
21st to endNight
2112223446%72%
1773
August1st to 10thNight
2111112235%81%
1765
11th to 20thNight
111112235%83%
1780
21st to endNight
11111123483%
1980
September1st to 10thNight
111111124482%
1840
11th to 20thNight
111112391%
1980
21st to endNight
111112489%
1980
October1st to 10thNight
111112335%82%
1980
11th to 20thNight
11111111389%
1980
21st to endNight
1112235%85%
2497
November1st to 10thNight
1112335%83%
2405
11th to 20thNight
1111212345%81%
2470
21st to endNight
2112212346%74%
2470
December1st to 10thNight
321222345%8%69%
2470
11th to 20thNight
231233445%11%64%
3041
21st to endNight
22144235%6%8%62%
4521

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
16%5%7%21%33%18%
1709
11th to 20thDay
14%48%16%35%22%
1665
21st to endDay
17%45%21%31%21%
1978
February1st to 10thDay
14%46%15%30%31%
1800
11th to 20thDay
12%5%5%17%30%31%
1760
21st to endDay
12%5%7%17%33%26%
1480
March1st to 10thDay
12%5%6%18%34%25%
1800
11th to 20thDay
12%46%18%33%27%
1916
21st to endDay
9%37%24%33%25%
2236
April1st to 10thDay
14%35%17%34%28%
2160
11th to 20thDay
8%2313%33%41%
2132
21st to endDay
6%25%14%33%39%
2173
May1st to 10thDay
7%2413%32%41%
2340
11th to 20thDay
6%239%33%46%
2304
21st to endDay
6%2412%32%43%
2530
June1st to 10thDay
6%249%25%56%
2340
11th to 20thDay
3127%15%72%
2340
21st to endDay
9%1249%75%
2340
July1st to 10thDay
9%347%14%64%
2276
11th to 20thDay
13%36%14%23%41%
2271
21st to endDay
18%7%7%16%20%32%
2404
August1st to 10thDay
11%35%9%20%53%
2153
11th to 20thDay
9%36%12%20%50%
2122
21st to endDay
9%3410%23%51%
2376
September1st to 10thDay
11%46%8%15%56%
2118
11th to 20thDay
4116%23%65%
1980
21st to endDay
7%237%26%55%
1980
October1st to 10thDay
9%3411%26%48%
1980
11th to 20thDay
6%248%29%52%
1980
21st to endDay
6%238%27%54%
1854
November1st to 10thDay
8%3413%32%40%
1674
11th to 20thDay
9%3414%30%39%
1710
21st to endDay
12%36%14%33%32%
1710
December1st to 10thDay
17%47%20%26%26%
1710
11th to 20thDay
18%7%11%24%25%15%
2168
21st to endDay
20%8%10%25%26%12%
3146
January1st to 10thNight
15%5%8%20%32%20%
2457
11th to 20thNight
14%6%6%18%32%24%
2405
21st to endNight
17%48%20%28%24%
2376
February1st to 10thNight
15%35%17%26%33%
2160
11th to 20thNight
13%46%15%31%31%
2099
21st to endNight
11%5%8%18%31%28%
1776
March1st to 10thNight
15%5%6%20%31%24%
2160
11th to 20thNight
10%47%20%33%27%
2043
21st to endNight
10%47%17%39%22%
2116
April1st to 10thNight
13%46%20%32%26%
1800
11th to 20thNight
8%3413%33%39%
1779
21st to endNight
5%2414%37%39%
1785
May1st to 10thNight
425%16%34%40%
1620
11th to 20thNight
5%2313%33%43%
1595
21st to endNight
41416%37%38%
1746
June1st to 10thNight
5%239%26%55%
1620
11th to 20thNight
4227%18%67%
1620
21st to endNight
6%115%12%74%
1620
July1st to 10thNight
6%135%16%68%
1575
11th to 20thNight
10%46%13%23%44%
1566
21st to endNight
13%5%7%19%24%33%
1674
August1st to 10thNight
7%349%21%56%
1756
11th to 20thNight
6%2411%25%52%
1780
21st to endNight
7%238%26%55%
1980
September1st to 10thNight
7%35%8%19%57%
1840
11th to 20thNight
3137%22%65%
1980
21st to endNight
4127%25%61%
1980
October1st to 10thNight
7%2411%30%45%
1980
11th to 20thNight
6%138%29%54%
1980
21st to endNight
6%248%24%56%
2497
November1st to 10thNight
7%35%11%36%39%
2405
11th to 20thNight
8%3314%32%40%
2470
21st to endNight
13%37%14%31%31%
2470
December1st to 10thNight
15%47%19%26%29%
2470
11th to 20thNight
16%7%11%19%29%18%
3041
21st to endNight
18%7%11%24%26%13%
4521

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
7%14%26%36%15%2
270
11th to 20thDay
10%8%28%34%18%2
255
21st to endDay
7%19%29%30%13%2
460
February1st to 10thDay
7%13%31%28%16%4
420
11th to 20thDay
7%21%32%28%12%1
415
21st to endDay
7%23%32%27%11%
346
March1st to 10thDay
8%21%30%29%12%1
420
11th to 20thDay
8%17%29%31%14%2
420
21st to endDay
8%22%35%27%8%2
462
April1st to 10thDay
6%17%27%28%18%5%
420
11th to 20thDay
323%32%24%15%3
412
21st to endDay
420%26%30%14%6%
420
May1st to 10thDay
414%29%35%14%5%
423
11th to 20thDay
113%28%37%16%6%
448
21st to endDay
312%27%35%18%5%
485
June1st to 10thDay
27%23%37%24%6%
450
11th to 20thDay
16%24%35%25%10%
450
21st to endDay
2424%37%23%10%
450
July1st to 10thDay
1116%41%30%12%
446
11th to 20thDay
212%38%33%15%
444
21st to endDay
3213%38%29%15%
487
August1st to 10thDay
2215%42%27%12%
447
11th to 20thDay
113%40%32%14%
437
21st to endDay
1113%38%31%16%
495
September1st to 10thDay
2218%43%28%8%
450
11th to 20thDay
1422%40%29%5%
450
21st to endDay
28%21%32%29%7%
450
October1st to 10thDay
29%25%36%24%4
450
11th to 20thDay
15%24%41%26%3
450
21st to endDay
28%21%35%27%7%
337
November1st to 10thDay
39%20%33%31%4
270
11th to 20thDay
37%22%39%25%5%
270
21st to endDay
313%22%35%23%4
270
December1st to 10thDay
5%7%30%35%21%3
270
11th to 20thDay
413%25%36%19%4
270
21st to endDay
8%13%32%28%15%3
297
January1st to 10thNight
39%23%34%23%9%
760
11th to 20thNight
26%23%39%24%7%
740
21st to endNight
5%8%27%35%21%5%
792
February1st to 10thNight
38%24%34%24%7%
720
11th to 20thNight
49%27%34%21%5%
704
21st to endNight
38%30%37%17%5%
592
March1st to 10thNight
310%29%34%21%3
720
11th to 20thNight
19%24%33%24%8%
720
21st to endNight
211%28%34%21%4
792
April1st to 10thNight
28%29%34%22%5%
720
11th to 20thNight
210%28%34%22%5%
711
21st to endNight
110%25%33%25%7%
705
May1st to 10thNight
16%26%40%24%3
540
11th to 20thNight
15%22%38%29%5%
531
21st to endNight
17%23%40%26%4
584
June1st to 10thNight
317%46%32%2
540
11th to 20thNight
120%44%33%2
540
21st to endNight
116%42%36%5%
540
July1st to 10thNight
2439%48%7%
525
11th to 20thNight
26%39%47%7%
522
21st to endNight
21438%49%6%
591
August1st to 10thNight
115%35%46%12%
691
11th to 20thNight
1226%54%16%
712
21st to endNight
21326%49%19%
792
September1st to 10thNight
115%29%50%14%
720
11th to 20thNight
18%36%45%11%
720
21st to endNight
1111%35%41%11%
720
October1st to 10thNight
1218%38%36%5%
720
11th to 20thNight
2213%39%36%9%
720
21st to endNight
15%15%35%32%14%
792
November1st to 10thNight
1318%34%34%10%
740
11th to 20thNight
1415%40%31%10%
760
21st to endNight
3421%37%28%7%
760
December1st to 10thNight
35%22%40%24%6%
760
11th to 20thNight
4424%37%26%5%
760
21st to endNight
411%25%37%18%6%
836
Page generated at 2024-01-12 22:38:12. Version ac07

Copyright 2024 Attilla Danko


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