This page made possible by the sponsorship of: Andy Schlei.

Mar Vista
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mar Vista 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
71%
24397
32%
74446
29%
24343
75%
24343
43%
39449

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
67%
756
28%
2646
29%
756
72%
756
39%
1325
January11th to 20thNight
69%
740
36%
2415
33%
740
77%
740
45%
1194
January21st to endNight
62%
792
39%
2383
34%
792
71%
792
43%
1258
February1st to 10thNight
67%
720
36%
2160
33%
720
73%
720
43%
1128
February11th to 20thNight
62%
700
33%
2098
30%
700
71%
700
43%
1117
February21st to endNight
59%
592
29%
1776
28%
592
66%
592
38%
975
March1st to 10thNight
59%
720
27%
2160
26%
720
66%
720
39%
1184
March11th to 20thNight
63%
720
25%
2097
23%
720
68%
720
36%
1223
March21st to endNight
64%
792
31%
1980
22%
792
69%
792
46%
1156
April1st to 10thNight
65%
720
30%
1800
20%
720
68%
720
43%
1074
April11th to 20thNight
66%
711
34%
1779
19%
711
71%
711
52%
981
April21st to endNight
65%
720
30%
1800
15%
720
70%
720
48%
1037
May1st to 10thNight
72%
689
26%
1769
16%
689
73%
689
46%
1022
May11th to 20thNight
69%
531
29%
1595
23%
531
70%
531
43%
886
May21st to endNight
71%
582
29%
1746
22%
582
73%
582
50%
893
June1st to 10thNight
70%
492
23%
1572
21%
492
71%
492
39%
885
June11th to 20thNight
80%
360
31%
1440
37%
360
80%
360
39%
660
June21st to endNight
76%
360
29%
1440
34%
360
76%
360
32%
716
July1st to 10thNight
81%
350
34%
1400
41%
350
81%
350
39%
653
July11th to 20thNight
84%
352
33%
1396
38%
352
84%
352
38%
651
July21st to endNight
79%
783
26%
1856
18%
740
79%
740
44%
1108
August1st to 10thNight
82%
716
32%
1780
21%
712
82%
712
54%
982
August11th to 20thNight
80%
712
35%
1780
22%
712
80%
712
51%
1002
August21st to endNight
82%
792
37%
1980
26%
792
82%
792
53%
1094
September1st to 10thNight
81%
720
36%
1800
29%
720
82%
720
53%
996
September11th to 20thNight
84%
720
42%
1916
39%
720
85%
720
58%
962
September21st to endNight
82%
720
40%
1980
38%
720
84%
720
56%
973
October1st to 10thNight
79%
720
37%
1980
36%
720
81%
720
53%
1009
October11th to 20thNight
76%
720
38%
2114
39%
720
79%
720
52%
1044
October21st to endNight
78%
792
41%
2389
42%
792
81%
792
55%
1120
November1st to 10thNight
76%
740
35%
2405
37%
740
80%
740
48%
1135
November11th to 20thNight
77%
760
38%
2470
40%
760
82%
760
50%
1143
November21st to endNight
71%
760
35%
2470
36%
760
76%
760
46%
1195
December1st to 10thNight
63%
760
33%
2470
30%
760
70%
760
39%
1290
December11th to 20thNight
62%
760
30%
2964
31%
759
69%
759
27%
1763
December21st to endNight
60%
823
20%
4640
30%
817
68%
817
20%
2615

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
4423323347%65%
74978
Night
6%5%24423447%59%
74827
TransparencyDay
22%25%20%28%24%
74705
Night
27%25%18%25%23%
74622
SeeingDay
5%6%20%37%25%7%
14487
Night
6%211%33%37%10%
24420

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
8%42443445%6%57%
1519
11th to 20thDay
7%423323446%61%
1651
21st to endDay
9%5%23322446%60%
1967
February1st to 10thDay
8%424323435%64%
1800
11th to 20thDay
7%21332435%7%63%
1750
21st to endDay
7%413422447%61%
1480
March1st to 10thDay
6%4244345%6%7%55%
1800
11th to 20thDay
6%42332346%10%56%
1857
21st to endDay
5%32232446%8%61%
2376
April1st to 10thDay
5%4134245%5%8%59%
2160
11th to 20thDay
331332335%7%67%
2129
21st to endDay
3313322438%68%
2160
May1st to 10thDay
342432345%9%62%
2188
11th to 20thDay
36%24322348%63%
2301
21st to endDay
45%23322447%65%
2530
June1st to 10thDay
5%6%24323348%60%
2382
11th to 20thDay
3423312337%68%
2520
21st to endDay
25%23323335%69%
2520
July1st to 10thDay
3314323347%67%
2520
11th to 20thDay
2313322345%72%
2511
21st to endDay
222232335%9%67%
2350
August1st to 10thDay
2312222336%73%
2149
11th to 20thDay
2312212337%75%
2122
21st to endDay
1212322346%74%
2376
September1st to 10thDay
2212222346%74%
2160
11th to 20thDay
2213213235%75%
2043
21st to endDay
2312313335%73%
1980
October1st to 10thDay
3313323246%71%
1980
11th to 20thDay
4212323245%73%
1841
21st to endDay
2213322446%71%
1965
November1st to 10thDay
2313323347%68%
1674
11th to 20thDay
431232335%6%68%
1710
21st to endDay
4313323449%62%
1710
December1st to 10thDay
7%43342445%6%57%
1710
11th to 20thDay
14%6%25%43436%7%46%
2169
21st to endDay
12%6%35%6%345%5%6%45%
2918
January1st to 10thNight
9%4233235%5%8%56%
2646
11th to 20thNight
6%424323348%61%
2415
21st to endNight
9%423323336%62%
2383
February1st to 10thNight
6%5%25%323436%61%
2160
11th to 20thNight
8%424423336%60%
2098
21st to endNight
9%4245%24335%59%
1776
March1st to 10thNight
7%6%25%424448%53%
2160
11th to 20thNight
8%5%25%6%345%5%7%51%
2097
21st to endNight
6%6%2332436%7%57%
1980
April1st to 10thNight
7%6%35%42435%6%56%
1800
11th to 20thNight
45%24322336%65%
1779
21st to endNight
35%3442445%8%58%
1800
May1st to 10thNight
46%3443345%8%56%
1769
11th to 20thNight
47%45%423347%56%
1594
21st to endNight
37%24213347%64%
1746
June1st to 10thNight
38%45%5%35%46%7%51%
1572
11th to 20thNight
36%35%3235%5%9%57%
1440
21st to endNight
18%26%5%345%5%8%51%
1440
July1st to 10thNight
3426%4245%48%58%
1440
11th to 20thNight
14246%345%6%9%56%
1444
21st to endNight
3435%6%345%5%10%52%
1965
August1st to 10thNight
24244236%5%8%60%
1790
11th to 20thNight
35%245%23449%59%
1780
21st to endNight
1425%4235%47%62%
1980
September1st to 10thNight
45%2332345%6%64%
1800
11th to 20thNight
2313313447%68%
1916
21st to endNight
2314323436%69%
1980
October1st to 10thNight
3423423446%66%
1980
11th to 20thNight
4423324445%66%
2114
21st to endNight
3313322346%70%
2389
November1st to 10thNight
2424224347%65%
2405
11th to 20thNight
3433323346%67%
2470
21st to endNight
442342445%7%61%
2470
December1st to 10thNight
6%5%26%433347%58%
2470
11th to 20thNight
15%7%35%423446%47%
3041
21st to endNight
14%6%25%5%25%5%5%6%45%
4738

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
29%25%21%23%21%
1519
11th to 20thDay
26%37%14%25%26%
1651
21st to endDay
28%25%20%17%28%
1967
February1st to 10thDay
25%2415%27%26%
1800
11th to 20thDay
22%25%20%27%25%
1760
21st to endDay
25%26%21%26%19%
1480
March1st to 10thDay
29%28%21%20%21%
1800
11th to 20thDay
25%210%22%25%17%
1857
21st to endDay
22%210%26%23%15%
2376
April1st to 10thDay
24%311%27%22%13%
2160
11th to 20thDay
18%27%26%29%18%
2132
21st to endDay
18%28%29%31%13%
2160
May1st to 10thDay
22%210%25%28%13%
2188
11th to 20thDay
23%26%27%30%12%
2304
21st to endDay
22%29%32%29%6%
2530
June1st to 10thDay
25%28%22%31%12%
2382
11th to 20thDay
19%15%15%35%25%
2520
21st to endDay
20%1210%33%33%
2520
July1st to 10thDay
20%1211%26%40%
2451
11th to 20thDay
17%15%19%33%25%
2436
21st to endDay
17%27%24%34%16%
2220
August1st to 10thDay
16%1115%34%33%
2135
11th to 20thDay
14%116%37%31%
2122
21st to endDay
14%2212%38%32%
2376
September1st to 10thDay
14%2212%35%36%
2160
11th to 20thDay
14%2115%34%34%
2043
21st to endDay
15%2117%36%28%
1980
October1st to 10thDay
18%1422%23%31%
1980
11th to 20thDay
16%1318%29%32%
1841
21st to endDay
16%2317%22%40%
1965
November1st to 10thDay
18%25%18%25%32%
1674
11th to 20thDay
19%25%17%20%37%
1710
21st to endDay
22%27%14%26%30%
1710
December1st to 10thDay
28%26%17%22%25%
1710
11th to 20thDay
38%27%15%22%16%
2168
21st to endDay
41%16%25%15%12%
2918
January1st to 10thNight
28%26%18%25%21%
2646
11th to 20thNight
24%37%17%21%29%
2415
21st to endNight
27%26%17%17%30%
2383
February1st to 10thNight
27%25%14%25%27%
2160
11th to 20thNight
28%2418%23%25%
2099
21st to endNight
31%26%16%25%21%
1776
March1st to 10thNight
31%27%20%22%19%
2160
11th to 20thNight
33%36%18%23%16%
2097
21st to endNight
28%310%23%23%14%
1980
April1st to 10thNight
31%29%26%19%13%
1800
11th to 20thNight
24%17%25%25%18%
1779
21st to endNight
27%28%24%26%12%
1800
May1st to 10thNight
28%210%23%25%11%
1769
11th to 20thNight
29%27%27%24%11%
1595
21st to endNight
23%29%33%26%7%
1746
June1st to 10thNight
31%310%21%25%10%
1572
11th to 20thNight
25%36%15%35%17%
1440
21st to endNight
31%238%29%26%
1440
July1st to 10thNight
26%3110%25%35%
1400
11th to 20thNight
24%4417%29%21%
1396
21st to endNight
30%35%23%26%13%
1856
August1st to 10thNight
23%2211%35%27%
1780
11th to 20thNight
25%211%35%27%
1780
21st to endNight
23%2112%33%29%
1980
September1st to 10thNight
24%227%32%33%
1800
11th to 20thNight
19%2212%33%33%
1916
21st to endNight
20%2116%34%28%
1980
October1st to 10thNight
22%1318%25%29%
1980
11th to 20thNight
22%2418%24%31%
2114
21st to endNight
19%2313%23%40%
2389
November1st to 10thNight
21%3417%22%34%
2405
11th to 20thNight
21%15%14%20%38%
2470
21st to endNight
24%26%18%21%30%
2470
December1st to 10thNight
29%26%14%21%28%
2470
11th to 20thNight
40%26%15%21%16%
3041
21st to endNight
42%17%22%16%12%
4738

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
15%6%22%37%19%2
180
11th to 20thDay
10%6%28%37%18%2
341
21st to endDay
9%11%27%38%14%2
457
February1st to 10thDay
10%6%29%32%18%5%
420
11th to 20thDay
9%13%29%33%13%3
415
21st to endDay
8%12%33%35%11%
346
March1st to 10thDay
10%13%34%28%14%1
420
11th to 20thDay
11%11%30%28%17%2
420
21st to endDay
8%15%31%33%12%2
462
April1st to 10thDay
7%10%28%33%17%5%
420
11th to 20thDay
312%37%33%11%4
412
21st to endDay
311%30%34%16%6%
420
May1st to 10thDay
410%30%38%15%3
423
11th to 20thDay
6%6%23%41%21%4
448
21st to endDay
5%5%28%39%18%5%
485
June1st to 10thDay
6%321%37%28%6%
450
11th to 20thDay
4316%40%29%8%
450
21st to endDay
3213%40%33%10%
450
July1st to 10thDay
26%39%41%12%
446
11th to 20thDay
2329%48%17%
444
21st to endDay
1337%41%18%
487
August1st to 10thDay
217%40%36%13%
447
11th to 20thDay
21437%43%12%
437
21st to endDay
217%39%39%13%
495
September1st to 10thDay
5%110%44%30%10%
450
11th to 20thDay
3216%45%28%8%
450
21st to endDay
2219%43%26%9%
450
October1st to 10thDay
2422%41%26%5%
450
11th to 20thDay
3224%43%22%6%
450
21st to endDay
46%21%37%25%7%
480
November1st to 10thDay
35%15%36%33%8%
270
11th to 20thDay
6%319%38%27%8%
270
21st to endDay
6%421%32%31%7%
270
December1st to 10thDay
9%418%40%27%3
270
11th to 20thDay
6%8%15%36%27%7%
270
21st to endDay
13%13%20%36%16%3
232
January1st to 10thNight
11%214%42%24%6%
760
11th to 20thNight
8%217%41%27%5%
740
21st to endNight
11%317%40%26%4
792
February1st to 10thNight
8%313%38%29%8%
720
11th to 20thNight
9%418%37%26%7%
704
21st to endNight
10%5%18%40%23%4
592
March1st to 10thNight
9%418%43%22%4
720
11th to 20thNight
9%414%37%30%7%
720
21st to endNight
8%5%17%40%26%4
792
April1st to 10thNight
9%313%41%29%5%
720
11th to 20thNight
6%416%37%32%5%
711
21st to endNight
5%416%35%33%8%
720
May1st to 10thNight
8%210%41%33%5%
689
11th to 20thNight
7%113%37%36%6%
531
21st to endNight
4117%35%37%5%
584
June1st to 10thNight
3113%34%43%6%
492
11th to 20thNight
41428%54%10%
360
21st to endNight
5%1426%54%11%
360
July1st to 10thNight
4111%65%19%
350
11th to 20thNight
317%64%26%
352
21st to endNight
4314%56%23%
783
August1st to 10thNight
41221%54%19%
716
11th to 20thNight
41313%56%23%
712
21st to endNight
2216%58%21%
792
September1st to 10thNight
7%1320%49%21%
720
11th to 20thNight
3427%53%13%
720
21st to endNight
215%29%50%13%
720
October1st to 10thNight
5%27%35%45%7%
720
11th to 20thNight
5%29%31%42%11%
720
21st to endNight
4210%32%39%14%
792
November1st to 10thNight
3310%35%37%12%
740
11th to 20thNight
5%18%38%36%12%
760
21st to endNight
6%213%40%32%7%
760
December1st to 10thNight
8%314%38%31%6%
760
11th to 20thNight
13%412%41%25%5%
760
21st to endNight
11%5%17%41%21%5%
836
Page generated at 2024-01-12 22:38:11. Version ac07

Copyright 2024 Attilla Danko


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