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 2018-02-22.

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
64%
16522
31%
48772
26%
16470
70%
16470
40%
25524

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%
776
28%
2656
25%
776
69%
776
33%
1339
January16th to endNight
57%
832
35%
2551
27%
832
68%
832
36%
1328
February1st to 15thNight
62%
760
34%
2281
33%
756
68%
756
38%
1193
February16th to endNight
52%
660
29%
1979
24%
660
61%
660
29%
1149
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
56%
719
28%
1799
16%
719
61%
719
40%
1041
April16th to endNight
59%
720
30%
1800
14%
720
64%
720
42%
1014
May1st to 15thNight
60%
639
26%
1719
15%
639
64%
639
37%
993
May16th to endNight
61%
561
26%
1685
18%
561
66%
561
39%
906
June1st to 15thNight
63%
461
23%
1541
20%
461
65%
461
33%
855
June16th to endNight
67%
360
27%
1440
28%
360
71%
360
31%
703
July1st to 15thNight
70%
340
29%
1360
32%
340
72%
340
35%
616
July16th to endNight
68%
649
24%
1667
18%
605
74%
605
42%
929
August1st to 15thNight
73%
717
30%
1790
20%
713
73%
713
48%
1004
August16th to endNight
77%
764
35%
1910
22%
764
80%
764
52%
1030
September1st to 15thNight
78%
720
34%
1821
26%
720
79%
720
51%
975
September16th to endNight
77%
716
40%
1980
35%
716
82%
716
56%
936
October1st to 15thNight
74%
720
34%
2007
33%
720
77%
720
50%
1027
October16th to endNight
72%
768
40%
2313
36%
768
79%
768
48%
1100
November1st to 15thNight
69%
760
33%
2470
34%
760
74%
760
45%
1136
November16th to endNight
64%
780
36%
2535
32%
780
73%
780
39%
1209
December1st to 15thNight
57%
780
33%
2535
29%
780
65%
780
32%
1314
December16th to endNight
55%
832
33%
2776
28%
832
65%
832
32%
1411

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
4312212247%65%
49448
Night
5%423323347%60%
48979
TransparencyDay
20%37%18%26%23%
49143
Night
24%37%17%24%23%
48784
SeeingDay
5%14%23%33%16%6%
6503
Night
6%15%5%26%33%12%
16533

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%413333245%59%
1610
16th to endDay
9%423222236%58%
2020
February1st to 15thDay
7%213213246%63%
1901
16th to endDay
9%422323347%55%
1641
March1st to 15thDay
431321345%7%62%
1800
16th to endDay
432342345%9%57%
2223
April1st to 15thDay
5%422323347%62%
2149
16th to endDay
3312312237%70%
2160
May1st to 15thDay
45%2221235%7%63%
2229
16th to endDay
45%12212238%65%
2429
June1st to 15thDay
7%6%23212238%59%
2415
16th to endDay
2312212225%73%
2520
July1st to 15thDay
4412212247%65%
2520
16th to endDay
2213112247%68%
2377
August1st to 15thDay
2311112136%74%
2160
16th to endDay
11112347%73%
2292
September1st to 15thDay
221223236%71%
2139
16th to endDay
2312212235%73%
1980
October1st to 15thDay
5%312222245%68%
1950
16th to endDay
3212313335%70%
1910
November1st to 15thDay
3213312346%66%
1719
16th to endDay
5%213212247%64%
1755
December1st to 15thDay
6%412313348%58%
1755
16th to endDay
9%313313347%59%
1794
January1st to 15thNight
7%41332345%7%57%
2656
16th to endNight
9%412222336%60%
2551
February1st to 15thNight
6%324323346%60%
2281
16th to endNight
11%5%24423335%53%
1979
March1st to 15thNight
6%42231235%8%59%
2160
16th to endNight
5%6%3332435%8%53%
1997
April1st to 15thNight
7%423312236%61%
1799
16th to endNight
45%23213337%62%
1800
May1st to 15thNight
6%6%23323347%55%
1719
16th to endNight
5%6%22313247%60%
1684
June1st to 15thNight
47%3322445%8%52%
1541
16th to endNight
27%3341445%7%55%
1440
July1st to 15thNight
35%2441325%9%56%
1440
16th to endNight
45%24424449%51%
1785
August1st to 15thNight
35%143223410%57%
1800
16th to endNight
15%1222345%9%60%
1910
September1st to 15thNight
231231435%7%63%
1821
16th to endNight
2412221236%70%
1980
October1st to 15thNight
3213323335%67%
2007
16th to endNight
4412212246%67%
2313
November1st to 15thNight
2313212347%66%
2470
16th to endNight
432231335%7%62%
2535
December1st to 15thNight
6%424413346%58%
2535
16th to endNight
10%313222346%59%
2776

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
27%26%15%22%25%
1610
16th to endDay
28%27%17%16%27%
2020
February1st to 15thDay
23%3416%26%24%
1901
16th to endDay
29%46%20%26%12%
1641
March1st to 15thDay
20%411%21%22%20%
1800
16th to endDay
24%412%24%19%14%
2223
April1st to 15thDay
21%411%26%23%11%
2149
16th to endDay
16%310%23%27%17%
2160
May1st to 15thDay
21%49%23%26%15%
2229
16th to endDay
21%38%30%27%8%
2432
June1st to 15thDay
26%47%16%32%14%
2415
16th to endDay
15%25%9%32%34%
2520
July1st to 15thDay
19%35%13%26%31%
2371
16th to endDay
16%39%20%32%16%
2232
August1st to 15thDay
13%2416%35%27%
2146
16th to endDay
10%35%14%39%25%
2292
September1st to 15thDay
14%27%14%30%29%
2139
16th to endDay
13%3415%32%29%
1980
October1st to 15thDay
18%26%20%25%25%
1950
16th to endDay
16%35%17%21%34%
1910
November1st to 15thDay
18%28%17%22%30%
1719
16th to endDay
21%27%14%22%30%
1755
December1st to 15thDay
25%38%16%20%26%
1755
16th to endDay
26%38%15%23%22%
1794
January1st to 15thNight
26%38%14%22%25%
2656
16th to endNight
25%37%16%17%29%
2551
February1st to 15thNight
25%26%15%23%25%
2292
16th to endNight
33%36%15%24%16%
1979
March1st to 15thNight
24%39%19%24%19%
2160
16th to endNight
28%6%11%19%20%13%
1997
April1st to 15thNight
26%38%25%23%12%
1799
16th to endNight
23%39%23%21%17%
1800
May1st to 15thNight
28%38%21%23%13%
1720
16th to endNight
25%39%27%24%9%
1685
June1st to 15thNight
29%5%10%15%28%11%
1541
16th to endNight
27%4411%27%25%
1440
July1st to 15thNight
23%35%13%25%28%
1360
16th to endNight
25%48%22%24%14%
1667
August1st to 15thNight
22%4412%35%21%
1790
16th to endNight
18%4413%35%23%
1910
September1st to 15thNight
19%45%9%33%27%
1821
16th to endNight
16%1316%31%30%
1980
October1st to 15thNight
20%25%17%28%24%
2007
16th to endNight
19%25%14%21%36%
2313
November1st to 15thNight
18%36%18%19%33%
2470
16th to endNight
21%36%16%22%29%
2535
December1st to 15thNight
27%27%15%19%27%
2535
16th to endNight
26%38%15%24%22%
2776

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%10%25%29%16%2
148
16th to endDay
9%18%24%28%15%3
339
February1st to 15thDay
9%16%24%24%15%9%
326
16th to endDay
10%23%31%22%8%3
264
March1st to 15thDay
5%23%30%21%13%4
270
16th to endDay
6%23%32%24%8%4
288
April1st to 15thDay
5%26%37%17%8%4
269
16th to endDay
127%38%25%24
270
May1st to 15thDay
421%31%29%9%2
288
16th to endDay
5%18%33%30%8%3
330
June1st to 15thDay
10%14%23%34%13%3
315
16th to endDay
10%19%45%14%9%
315
July1st to 15thDay
5%8%12%43%21%8%
305
16th to endDay
210%10%44%20%12%
327
August1st to 15thDay
36%14%47%20%7%
315
16th to endDay
15%12%47%24%9%
332
September1st to 15thDay
26%24%41%17%6%
315
16th to endDay
28%26%40%14%7%
315
October1st to 15thDay
5%11%27%34%17%3
315
16th to endDay
39%23%36%17%8%
326
November1st to 15thDay
5%5%12%25%31%18%
135
16th to endDay
36%16%31%32%9%
135
December1st to 15thDay
2414%35%31%12%
135
16th to endDay
9%7%15%27%30%8%
126
January1st to 15thNight
9%16%5%32%27%8%
780
16th to endNight
10%18%7%29%27%7%
832
February1st to 15thNight
6%17%6%30%30%9%
764
16th to endNight
11%18%7%31%25%5%
660
March1st to 15thNight
5%18%6%36%25%6%
720
16th to endNight
420%7%32%27%7%
768
April1st to 15thNight
7%21%9%30%26%5%
719
16th to endNight
5%20%8%31%28%7%
720
May1st to 15thNight
5%19%7%28%31%7%
640
16th to endNight
419%9%32%29%5%
563
June1st to 15thNight
418%6%26%36%7%
461
16th to endNight
418%16%49%10%
360
July1st to 15thNight
5%12%249%29%
340
16th to endNight
417%12%38%26%
649
August1st to 15thNight
6%10%116%43%21%
717
16th to endNight
49%112%45%27%
764
September1st to 15thNight
49%18%45%21%
720
16th to endNight
49%220%48%14%
716
October1st to 15thNight
39%426%43%12%
720
16th to endNight
7%10%423%37%17%
768
November1st to 15thNight
314%428%35%12%
760
16th to endNight
6%17%427%32%12%
780
December1st to 15thNight
7%18%5%33%26%7%
780
16th to endNight
11%19%6%32%22%6%
832
Page generated at 2018-02-23 08:21:38. Version ac04

Copyright 2018 A. Danko


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