Redondo Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Redondo Beach clear sky chart from 2005-11-05 to 2017-04-02.

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
63%
15338
31%
45252
25%
15286
70%
15286
39%
23732

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
60%
716
28%
2451
24%
716
70%
716
34%
1215
January16th to endNight
56%
768
34%
2355
26%
768
67%
768
34%
1244
February1st to 15thNight
60%
700
34%
2101
32%
696
67%
696
37%
1110
February16th to endNight
50%
632
27%
1895
22%
632
60%
632
27%
1116
March1st to 15thNight
60%
720
29%
2160
27%
720
68%
720
38%
1118
March16th to endNight
58%
768
26%
1997
19%
768
63%
768
35%
1198
April1st to 15thNight
55%
666
30%
1667
17%
666
61%
666
40%
967
April16th to endNight
58%
660
27%
1650
13%
660
63%
660
41%
940
May1st to 15thNight
60%
586
26%
1576
15%
586
64%
586
36%
917
May16th to endNight
60%
513
25%
1541
17%
513
65%
513
39%
829
June1st to 15thNight
63%
423
24%
1413
21%
423
66%
423
33%
779
June16th to endNight
67%
330
26%
1320
26%
330
72%
330
31%
645
July1st to 15thNight
70%
310
31%
1240
34%
310
72%
310
35%
557
July16th to endNight
67%
601
24%
1535
17%
557
74%
557
42%
846
August1st to 15thNight
73%
657
32%
1640
21%
653
74%
653
49%
908
August16th to endNight
78%
700
34%
1750
21%
700
80%
700
52%
935
September1st to 15thNight
78%
660
35%
1669
27%
660
79%
660
50%
893
September16th to endNight
76%
656
38%
1815
33%
656
82%
656
55%
863
October1st to 15thNight
73%
660
34%
1840
34%
660
75%
660
49%
952
October16th to endNight
71%
704
38%
2120
34%
704
79%
704
47%
1010
November1st to 15thNight
68%
700
34%
2275
35%
700
74%
700
46%
1024
November16th to endNight
63%
720
35%
2340
30%
720
74%
720
39%
1112
December1st to 15thNight
54%
720
33%
2340
28%
720
64%
720
30%
1233
December16th to endNight
52%
768
31%
2562
26%
768
63%
768
30%
1321

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
5%312212346%65%
45838
Night
5%423323347%60%
45459
TransparencyDay
20%37%18%26%22%
45533
Night
24%37%17%24%22%
45264
SeeingDay
5%16%25%33%14%4
5303
Night
6%16%5%26%33%11%
15349

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%413323245%60%
1485
16th to endDay
10%423222337%57%
1864
February1st to 15thDay
7%313213346%62%
1751
16th to endDay
10%423323347%54%
1579
March1st to 15thDay
431321345%7%62%
1800
16th to endDay
432342345%9%57%
2223
April1st to 15thDay
5%422323347%61%
1983
16th to endDay
3312312237%70%
1980
May1st to 15thDay
45%22212347%63%
2042
16th to endDay
45%12212238%65%
2221
June1st to 15thDay
7%6%23212238%59%
2214
16th to endDay
2312112225%73%
2310
July1st to 15thDay
4412212247%65%
2310
16th to endDay
3213112246%69%
2201
August1st to 15thDay
2311112136%75%
1980
16th to endDay
11112347%74%
2100
September1st to 15thDay
221212236%72%
1961
16th to endDay
231212235%73%
1815
October1st to 15thDay
5%312222245%67%
1788
16th to endDay
3212313335%69%
1751
November1st to 15thDay
3213312336%69%
1584
16th to endDay
5%313212246%65%
1620
December1st to 15thDay
7%412313448%56%
1620
16th to endDay
10%313313337%58%
1656
January1st to 15thNight
6%41322345%6%59%
2451
16th to endNight
10%412223336%59%
2355
February1st to 15thNight
6%324313336%60%
2101
16th to endNight
11%5%24423345%52%
1895
March1st to 15thNight
6%42231235%8%59%
2160
16th to endNight
5%6%3332435%8%53%
1997
April1st to 15thNight
8%42322236%61%
1667
16th to endNight
45%23213336%62%
1650
May1st to 15thNight
6%6%23323348%55%
1576
16th to endNight
5%6%12313248%60%
1540
June1st to 15thNight
37%2322445%9%52%
1413
16th to endNight
27%23425%35%7%56%
1320
July1st to 15thNight
35%235%1325%9%56%
1320
16th to endNight
45%24425%449%52%
1653
August1st to 15thNight
341332235%10%58%
1650
16th to endNight
15%1222345%9%62%
1750
September1st to 15thNight
231231445%7%62%
1669
16th to endNight
2412221236%69%
1815
October1st to 15thNight
3213323335%66%
1840
16th to endNight
5%412212246%66%
2120
November1st to 15thNight
331222236%69%
2275
16th to endNight
4312313347%63%
2340
December1st to 15thNight
7%424413336%58%
2340
16th to endNight
11%313222235%59%
2562

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
26%26%14%22%27%
1485
16th to endDay
29%27%16%16%27%
1864
February1st to 15thDay
23%35%17%25%23%
1751
16th to endDay
30%46%21%26%10%
1579
March1st to 15thDay
20%411%21%22%20%
1800
16th to endDay
24%412%24%19%14%
2223
April1st to 15thDay
22%412%26%22%12%
1983
16th to endDay
17%410%23%28%15%
1980
May1st to 15thDay
21%49%23%25%16%
2042
16th to endDay
21%38%31%27%6%
2224
June1st to 15thDay
26%47%15%33%13%
2214
16th to endDay
16%25%10%34%30%
2310
July1st to 15thDay
19%35%14%25%31%
2161
16th to endDay
17%49%19%31%17%
2056
August1st to 15thDay
12%2417%36%26%
1966
16th to endDay
10%35%15%39%24%
2100
September1st to 15thDay
14%27%13%29%31%
1961
16th to endDay
13%3414%32%30%
1815
October1st to 15thDay
19%27%22%24%23%
1788
16th to endDay
17%35%17%22%33%
1751
November1st to 15thDay
18%27%15%23%33%
1584
16th to endDay
21%28%15%21%30%
1620
December1st to 15thDay
26%38%16%20%23%
1620
16th to endDay
27%49%15%22%21%
1656
January1st to 15thNight
25%38%13%22%27%
2451
16th to endNight
26%37%15%16%29%
2355
February1st to 15thNight
26%26%15%22%25%
2112
16th to endNight
34%47%15%23%14%
1895
March1st to 15thNight
24%39%19%24%19%
2160
16th to endNight
28%6%11%19%20%13%
1997
April1st to 15thNight
26%39%25%21%13%
1667
16th to endNight
24%310%22%21%17%
1650
May1st to 15thNight
29%38%20%23%14%
1577
16th to endNight
25%39%28%24%8%
1541
June1st to 15thNight
28%5%11%14%29%10%
1413
16th to endNight
26%5%5%11%29%22%
1320
July1st to 15thNight
22%35%14%25%27%
1240
16th to endNight
24%49%21%23%15%
1535
August1st to 15thNight
21%4413%35%20%
1640
16th to endNight
17%4414%34%23%
1750
September1st to 15thNight
19%46%9%31%28%
1669
16th to endNight
16%1316%31%30%
1815
October1st to 15thNight
21%25%17%28%23%
1840
16th to endNight
19%25%14%22%34%
2120
November1st to 15thNight
17%36%16%20%36%
2275
16th to endNight
20%36%17%21%30%
2340
December1st to 15thNight
29%28%15%20%24%
2340
16th to endNight
27%38%15%23%20%
2562

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
17%12%26%31%11%
113
16th to endDay
11%20%26%28%11%2
279
February1st to 15thDay
10%18%26%23%14%5%
266
16th to endDay
12%23%32%21%7%2
238
March1st to 15thDay
5%23%30%21%13%4
270
16th to endDay
6%23%32%24%8%4
288
April1st to 15thDay
6%31%36%15%6%3
214
16th to endDay
129%37%27%13
210
May1st to 15thDay
424%32%28%9%1
228
16th to endDay
5%21%33%30%6%1
266
June1st to 15thDay
9%16%25%33%12%1
255
16th to endDay
13%21%43%12%8%
255
July1st to 15thDay
6%10%15%45%18%4
245
16th to endDay
212%11%43%20%9%
271
August1st to 15thDay
38%16%48%17%6%
255
16th to endDay
17%11%50%22%7%
268
September1st to 15thDay
37%21%44%18%5%
255
16th to endDay
18%27%43%11%6%
255
October1st to 15thDay
5%13%29%34%14%2
255
16th to endDay
411%25%37%16%4
263
November1st to 15thDay
36%6%23%32%27%
90
16th to endDay
37%18%33%34%2
90
December1st to 15thDay
36%14%35%33%6%
90
16th to endDay
14%10%16%30%22%4
84
January1st to 15thNight
9%17%5%32%26%8%
720
16th to endNight
11%18%7%29%25%7%
768
February1st to 15thNight
6%19%6%30%29%7%
704
16th to endNight
12%18%7%30%25%5%
632
March1st to 15thNight
5%18%6%36%25%6%
720
16th to endNight
420%7%32%27%7%
768
April1st to 15thNight
7%22%9%30%25%5%
666
16th to endNight
5%20%7%30%28%7%
660
May1st to 15thNight
5%20%7%28%32%5%
587
16th to endNight
420%9%31%28%4
515
June1st to 15thNight
319%7%26%36%7%
423
16th to endNight
419%16%48%9%
330
July1st to 15thNight
5%13%248%29%
310
16th to endNight
418%11%38%25%
601
August1st to 15thNight
5%10%115%43%21%
657
16th to endNight
49%112%45%27%
700
September1st to 15thNight
39%16%46%22%
660
16th to endNight
410%119%48%15%
656
October1st to 15thNight
39%5%26%42%12%
660
16th to endNight
7%10%423%37%16%
704
November1st to 15thNight
315%426%35%13%
700
16th to endNight
6%18%427%31%11%
720
December1st to 15thNight
8%19%5%33%26%7%
720
16th to endNight
12%20%7%33%20%5%
768
Page generated at 2017-04-02 22:35:05. Version ac04

Copyright 2017 A. Danko


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