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 2005-11-05 to 2019-09-17.

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%
18523
33%
54702
30%
18474
77%
18474
47%
28170

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
71%
836
29%
2863
30%
836
77%
836
40%
1445
January16th to endNight
68%
896
35%
2764
33%
896
74%
896
43%
1437
February1st to 15thNight
69%
818
36%
2461
35%
816
75%
816
44%
1279
February16th to endNight
60%
736
28%
2207
27%
736
65%
736
35%
1251
March1st to 15thNight
67%
840
28%
2520
28%
840
71%
840
42%
1337
March16th to endNight
68%
896
28%
2331
22%
896
71%
896
43%
1353
April1st to 15thNight
64%
839
31%
2099
19%
839
70%
839
46%
1206
April16th to endNight
69%
832
31%
2080
16%
832
74%
832
51%
1147
May1st to 15thNight
72%
745
28%
2005
19%
745
73%
745
46%
1127
May16th to endNight
69%
657
28%
1973
22%
657
71%
657
49%
1021
June1st to 15thNight
76%
522
27%
1782
27%
522
77%
522
41%
919
June16th to endNight
79%
420
30%
1680
36%
420
79%
420
37%
778
July1st to 15thNight
84%
400
33%
1600
40%
400
84%
400
41%
721
July16th to endNight
79%
741
26%
1952
21%
698
79%
698
44%
1089
August1st to 15thNight
81%
825
35%
2060
23%
821
81%
821
55%
1116
August16th to endNight
83%
892
37%
2230
25%
892
83%
892
55%
1212
September1st to 15thNight
85%
840
38%
2120
30%
840
85%
840
57%
1132
September16th to endNight
85%
780
41%
2157
40%
780
86%
780
63%
999
October1st to 15thNight
81%
780
38%
2177
37%
780
83%
780
55%
1081
October16th to endNight
80%
832
41%
2506
43%
832
82%
832
54%
1178
November1st to 15thNight
80%
820
37%
2665
41%
820
84%
820
54%
1181
November16th to endNight
77%
840
36%
2730
38%
840
81%
840
49%
1268
December1st to 15thNight
68%
840
36%
2730
35%
840
74%
840
41%
1389
December16th to endNight
65%
896
33%
3010
32%
896
71%
896
39%
1504

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
4312312347%65%
55952
Night
4413323347%60%
54908
TransparencyDay
20%26%19%28%23%
55647
Night
24%25%18%26%23%
54714
SeeingDay
6%8%25%35%17%6%
8649
Night
6%37%31%38%12%
18536

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
7%42442334459%
1731
16th to endDay
9%422212336%59%
2159
February1st to 15thDay
7%313212345%62%
2051
16th to endDay
8%313313347%57%
1839
March1st to 15thDay
5%41332335%7%59%
2100
16th to endDay
431332445%9%56%
2592
April1st to 15thDay
4313323448%60%
2509
16th to endDay
2312312437%67%
2485
May1st to 15thDay
3413222348%61%
2603
16th to endDay
35%12212347%64%
2845
June1st to 15thDay
46%13312247%61%
2832
16th to endDay
2412212226%71%
2940
July1st to 15thDay
3313312347%66%
2940
16th to endDay
2212222347%68%
2795
August1st to 15thDay
1212112226%74%
2473
16th to endDay
111212246%74%
2676
September1st to 15thDay
122212245%74%
2499
16th to endDay
122212235%74%
2157
October1st to 15thDay
422312245%68%
2109
16th to endDay
212212346%71%
2068
November1st to 15thDay
3212212246%68%
1854
16th to endDay
4213323348%63%
1890
December1st to 15thDay
6%32331435%7%59%
1890
16th to endDay
8%214313346%60%
1915
January1st to 15thNight
7%423313447%56%
2863
16th to endNight
9%313312336%60%
2764
February1st to 15thNight
6%324313336%61%
2461
16th to endNight
11%414413336%54%
2207
March1st to 15thNight
6%414423348%56%
2520
16th to endNight
45%1343446%7%54%
2331
April1st to 15thNight
6%5%23313246%60%
2099
16th to endNight
3423323348%61%
2080
May1st to 15thNight
45%24322348%57%
2005
16th to endNight
35%24312347%61%
1972
June1st to 15thNight
25%3432446%8%53%
1782
16th to endNight
16%2442345%8%55%
1680
July1st to 15thNight
231442435%8%59%
1680
16th to endNight
34245%3445%10%52%
2069
August1st to 15thNight
242341235%8%60%
2070
16th to endNight
1413323449%61%
2230
September1st to 15thNight
2312223347%65%
2120
16th to endNight
1312212236%72%
2157
October1st to 15thNight
3212313436%66%
2177
16th to endNight
3312212236%69%
2506
November1st to 15thNight
1322212246%68%
2665
16th to endNight
4312213347%64%
2730
December1st to 15thNight
5%325%323336%59%
2730
16th to endNight
9%313312336%61%
3010

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
28%25%15%22%25%
1731
16th to endDay
28%26%18%17%27%
2159
February1st to 15thDay
24%2417%27%24%
2051
16th to endDay
27%26%22%28%12%
1839
March1st to 15thDay
24%19%22%22%19%
2100
16th to endDay
23%211%25%21%15%
2592
April1st to 15thDay
22%210%26%24%12%
2509
16th to endDay
17%29%26%28%16%
2485
May1st to 15thDay
22%210%23%26%14%
2603
16th to endDay
21%28%32%28%7%
2848
June1st to 15thDay
23%16%19%33%14%
2832
16th to endDay
17%1211%34%32%
2940
July1st to 15thDay
19%1213%29%32%
2791
16th to endDay
16%27%23%32%17%
2650
August1st to 15thDay
13%116%37%30%
2459
16th to endDay
12%1115%42%26%
2676
September1st to 15thDay
13%2215%33%33%
2499
16th to endDay
13%1116%35%30%
2157
October1st to 15thDay
18%1424%25%25%
2109
16th to endDay
15%2317%24%37%
2068
November1st to 15thDay
17%25%17%24%32%
1854
16th to endDay
21%27%15%23%29%
1890
December1st to 15thDay
24%27%17%21%26%
1890
16th to endDay
25%27%18%24%21%
1915
January1st to 15thNight
26%27%15%20%26%
2863
16th to endNight
25%26%17%17%29%
2764
February1st to 15thNight
26%15%16%25%24%
2472
16th to endNight
32%26%16%25%16%
2207
March1st to 15thNight
27%28%20%23%17%
2520
16th to endNight
28%39%21%22%14%
2331
April1st to 15thNight
26%28%25%23%13%
2099
16th to endNight
22%27%25%24%16%
2080
May1st to 15thNight
27%210%23%24%12%
2006
16th to endNight
23%29%30%25%8%
1973
June1st to 15thNight
25%49%17%31%11%
1782
16th to endNight
25%2311%31%24%
1680
July1st to 15thNight
22%3113%28%30%
1600
16th to endNight
26%45%22%25%15%
1952
August1st to 15thNight
21%211%37%26%
2060
16th to endNight
21%311%38%24%
2230
September1st to 15thNight
20%228%34%31%
2120
16th to endNight
15%116%33%32%
2157
October1st to 15thNight
19%2322%29%23%
2177
16th to endNight
18%2314%22%38%
2506
November1st to 15thNight
17%15%18%20%35%
2665
16th to endNight
21%15%19%22%28%
2730
December1st to 15thNight
27%26%17%20%26%
2730
16th to endNight
26%27%15%25%22%
3010

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
16%6%29%30%15%1
179
16th to endDay
11%9%31%31%12%2
393
February1st to 15thDay
12%11%28%25%14%6%
386
16th to endDay
10%18%33%24%10%2
342
March1st to 15thDay
11%17%33%22%12%2
390
16th to endDay
8%12%35%26%12%2
416
April1st to 15thDay
8%13%38%21%12%5%
389
16th to endDay
5%18%37%27%5%5%
378
May1st to 15thDay
8%12%32%31%11%3
408
16th to endDay
7%14%35%29%10%2
458
June1st to 15thDay
8%7%22%39%17%5%
435
16th to endDay
3217%47%18%10%
435
July1st to 15thDay
3112%46%26%9%
425
16th to endDay
119%49%24%12%
455
August1st to 15thDay
2115%49%21%9%
419
16th to endDay
213%48%24%10%
460
September1st to 15thDay
5%125%41%18%7%
435
16th to endDay
2429%41%15%7%
380
October1st to 15thDay
5%9%31%33%16%3
375
16th to endDay
35%25%36%19%9%
388
November1st to 15thDay
45%11%30%33%15%
180
16th to endDay
5%416%32%29%11%
180
December1st to 15thDay
6%6%17%32%29%8%
180
16th to endDay
6%12%14%33%25%7%
163
January1st to 15thNight
9%38%40%29%8%
840
16th to endNight
12%210%35%30%8%
896
February1st to 15thNight
9%29%35%32%10%
824
16th to endNight
12%5%11%36%28%5%
736
March1st to 15thNight
8%311%43%26%6%
840
16th to endNight
7%411%38%31%6%
896
April1st to 15thNight
9%6%11%36%30%5%
839
16th to endNight
46%10%38%31%8%
832
May1st to 15thNight
7%48%35%37%7%
746
16th to endNight
5%315%37%32%5%
659
June1st to 15thNight
437%31%42%11%
522
16th to endNight
4319%59%12%
420
July1st to 15thNight
325%61%25%
400
16th to endNight
43114%50%26%
741
August1st to 15thNight
42219%49%20%
825
16th to endNight
22214%51%26%
892
September1st to 15thNight
5%1121%48%20%
840
16th to endNight
32223%55%12%
780
October1st to 15thNight
415%36%41%11%
780
16th to endNight
6%2428%40%17%
832
November1st to 15thNight
32435%39%14%
820
16th to endNight
6%36%31%38%13%
840
December1st to 15thNight
8%38%37%33%8%
840
16th to endNight
11%5%9%39%25%7%
896
Page generated at 2019-09-17 18:12:18. Version ac04

Copyright 2019 A. Danko


Mar Vista Clear Sky Chart |Charts Home