Huntington Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huntington Beach clear sky chart from 2005-11-05 to 2017-12-20.

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%
16340
30%
47868
25%
16289
69%
16289
38%
25793

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
59%
718
29%
2391
24%
716
68%
716
34%
1180
January16th to endNight
53%
768
34%
2304
24%
768
65%
768
34%
1239
February1st to 15thNight
59%
700
34%
2102
32%
697
65%
697
36%
1118
February16th to endNight
53%
632
27%
1895
22%
632
62%
632
28%
1121
March1st to 15thNight
59%
720
29%
2160
26%
720
67%
720
37%
1144
March16th to endNight
60%
768
26%
2009
20%
768
65%
768
37%
1168
April1st to 15thNight
59%
719
27%
1799
17%
719
63%
719
41%
1047
April16th to endNight
59%
720
29%
1800
15%
720
63%
720
40%
1036
May1st to 15thNight
59%
623
25%
1703
16%
623
62%
623
35%
1018
May16th to endNight
60%
561
24%
1685
15%
561
64%
561
36%
961
June1st to 15thNight
59%
519
21%
1599
16%
519
62%
519
29%
967
June16th to endNight
62%
360
25%
1440
25%
360
67%
360
25%
775
July1st to 15thNight
65%
340
28%
1360
29%
340
68%
340
29%
668
July16th to endNight
66%
680
23%
1700
15%
638
72%
638
39%
1000
August1st to 15thNight
70%
717
29%
1790
18%
713
71%
713
44%
1031
August16th to endNight
76%
764
34%
1910
20%
764
79%
764
48%
1061
September1st to 15thNight
73%
720
31%
1835
24%
720
75%
720
45%
1045
September16th to endNight
75%
716
38%
1980
34%
716
80%
716
52%
978
October1st to 15thNight
73%
720
34%
1980
32%
720
75%
720
49%
1032
October16th to endNight
73%
768
38%
2328
36%
768
79%
768
45%
1147
November1st to 15thNight
70%
760
32%
2470
34%
760
74%
760
44%
1147
November16th to endNight
64%
780
36%
2535
34%
780
72%
780
38%
1237
December1st to 15thNight
55%
780
32%
2535
28%
780
65%
780
31%
1333
December16th to endNight
50%
787
33%
2558
25%
787
62%
787
31%
1340

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
4312213348%62%
48925
Night
5%5%23323347%56%
48073
TransparencyDay
21%37%19%26%22%
48620
Night
26%37%16%23%22%
47879
SeeingDay
5%10%16%36%24%5%
6291
Night
7%15%5%24%34%12%
16349

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
6%423323347%58%
1520
16th to endDay
9%5%23213335%57%
1920
February1st to 15thDay
6%313213347%60%
1751
16th to endDay
10%5%2432335%8%51%
1579
March1st to 15thDay
421231337%9%59%
1800
16th to endDay
441332436%9%56%
2211
April1st to 15thDay
4412224447%61%
2149
16th to endDay
3312213347%66%
2160
May1st to 15thDay
4422313348%62%
2246
16th to endDay
5%5%13322338%62%
2429
June1st to 15thDay
7%6%23312348%55%
2355
16th to endDay
2412213238%67%
2520
July1st to 15thDay
342232345%10%57%
2517
16th to endDay
2312223348%64%
2348
August1st to 15thDay
2312211237%70%
2160
16th to endDay
1212123410%68%
2292
September1st to 15thDay
131222235%7%67%
2124
16th to endDay
1312112237%70%
1980
October1st to 15thDay
5%313212346%65%
1977
16th to endDay
4212322346%65%
1894
November1st to 15thDay
3223313347%65%
1719
16th to endDay
5%313313348%62%
1755
December1st to 15thDay
5%41431335%7%57%
1755
16th to endDay
9%22231225%6%59%
1764
January1st to 15thNight
5%423423336%60%
2391
16th to endNight
9%423312336%59%
2304
February1st to 15thNight
6%424323236%59%
2101
16th to endNight
11%6%24423435%50%
1895
March1st to 15thNight
5%5%23323348%57%
2160
16th to endNight
5%6%24324449%52%
2009
April1st to 15thNight
8%6%23212236%59%
1799
16th to endNight
6%6%13222346%60%
1800
May1st to 15thNight
8%9%33323239%50%
1703
16th to endNight
7%7%1332335%8%52%
1684
June1st to 15thNight
8%10%3442245%9%42%
1599
16th to endNight
311%45%334448%45%
1440
July1st to 15thNight
48%35%32445%10%47%
1440
16th to endNight
47%245%335%7%10%45%
1817
August1st to 15thNight
47%23423448%53%
1800
16th to endNight
242342445%10%56%
1910
September1st to 15thNight
3424324447%57%
1835
16th to endNight
36%22212338%64%
1980
October1st to 15thNight
3313323337%63%
1980
16th to endNight
5%412313337%64%
2328
November1st to 15thNight
3412313346%65%
2470
16th to endNight
35%13323348%60%
2535
December1st to 15thNight
7%414422346%57%
2535
16th to endNight
10%423212235%59%
2558

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%36%14%21%27%
1520
16th to endDay
29%27%16%15%27%
1920
February1st to 15thDay
24%36%17%24%23%
1751
16th to endDay
30%48%22%24%9%
1579
March1st to 15thDay
20%311%22%21%20%
1800
16th to endDay
24%413%25%18%13%
2211
April1st to 15thDay
22%311%29%22%10%
2149
16th to endDay
18%211%24%25%16%
2160
May1st to 15thDay
22%39%24%26%14%
2246
16th to endDay
22%29%31%26%7%
2432
June1st to 15thDay
27%37%18%30%13%
2355
16th to endDay
17%2310%32%33%
2520
July1st to 15thDay
20%3412%28%30%
2368
16th to endDay
18%38%23%30%15%
2203
August1st to 15thDay
14%2117%36%27%
2146
16th to endDay
13%2315%40%25%
2292
September1st to 15thDay
14%3414%34%27%
2124
16th to endDay
14%2217%33%29%
1980
October1st to 15thDay
20%26%21%24%25%
1977
16th to endDay
20%26%15%19%35%
1894
November1st to 15thDay
19%28%18%19%30%
1719
16th to endDay
20%38%15%22%30%
1755
December1st to 15thDay
25%49%16%18%25%
1755
16th to endDay
26%310%17%21%20%
1764
January1st to 15thNight
25%28%13%22%27%
2391
16th to endNight
27%38%15%15%29%
2304
February1st to 15thNight
27%26%16%21%26%
2112
16th to endNight
35%37%14%24%14%
1895
March1st to 15thNight
25%38%21%21%19%
2160
16th to endNight
28%412%21%20%13%
2009
April1st to 15thNight
27%210%25%21%12%
1799
16th to endNight
26%310%22%22%16%
1800
May1st to 15thNight
31%38%21%21%12%
1704
16th to endNight
29%310%25%20%10%
1685
June1st to 15thNight
36%39%15%25%10%
1599
16th to endNight
34%327%26%24%
1440
July1st to 15thNight
29%3313%25%26%
1360
16th to endNight
29%49%19%23%13%
1700
August1st to 15thNight
27%2216%33%18%
1790
16th to endNight
22%3313%32%24%
1910
September1st to 15thNight
25%349%31%25%
1835
16th to endNight
19%1312%32%29%
1980
October1st to 15thNight
21%35%17%29%23%
1980
16th to endNight
22%2413%22%34%
2328
November1st to 15thNight
20%27%18%19%32%
2470
16th to endNight
23%36%17%19%29%
2535
December1st to 15thNight
28%37%15%19%26%
2535
16th to endNight
28%39%16%22%20%
2558

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
12%9%18%45%13%
107
16th to endDay
10%18%23%30%15%1
288
February1st to 15thDay
9%15%19%29%23%2
266
16th to endDay
11%14%26%30%15%1
238
March1st to 15thDay
5%17%21%32%17%4
270
16th to endDay
5%19%19%37%15%3
288
April1st to 15thDay
417%27%33%13%3
269
16th to endDay
218%32%33%8%3
270
May1st to 15thDay
5%14%24%35%15%3
288
16th to endDay
6%13%20%41%14%2
330
June1st to 15thDay
10%10%19%33%24%2
315
16th to endDay
29%6%41%32%7%
315
July1st to 15thDay
36%6%36%37%9%
305
16th to endDay
39%432%38%11%
327
August1st to 15thDay
5%5%7%38%38%5%
315
16th to endDay
24436%41%9%
332
September1st to 15thDay
25%11%47%28%4
315
16th to endDay
36%13%45%24%6%
315
October1st to 15thDay
5%5%22%39%21%4
315
16th to endDay
45%18%35%26%9%
310
November1st to 15thDay
25%14%32%31%12%
135
16th to endDay
5%6%16%29%29%11%
135
December1st to 15thDay
35%15%37%29%7%
135
16th to endDay
9%8%21%32%25%3
108
January1st to 15thNight
6%18%8%32%25%7%
720
16th to endNight
11%17%10%26%28%5%
768
February1st to 15thNight
7%18%7%29%28%7%
704
16th to endNight
11%17%7%31%26%5%
632
March1st to 15thNight
7%18%8%31%27%6%
720
16th to endNight
7%18%7%25%34%6%
768
April1st to 15thNight
7%19%8%31%27%6%
719
16th to endNight
8%19%6%28%29%7%
720
May1st to 15thNight
8%18%6%26%33%6%
624
16th to endNight
6%18%9%30%31%4
563
June1st to 15thNight
9%17%429%33%5%
519
16th to endNight
6%17%113%46%13%
360
July1st to 15thNight
6%12%25%45%28%
340
16th to endNight
5%17%8%41%25%
680
August1st to 15thNight
8%10%111%43%23%
717
16th to endNight
5%8%9%43%31%
764
September1st to 15thNight
5%9%213%47%22%
720
16th to endNight
5%9%120%46%15%
716
October1st to 15thNight
5%9%424%44%11%
720
16th to endNight
6%9%423%39%17%
768
November1st to 15thNight
414%430%34%11%
760
16th to endNight
6%16%427%32%11%
780
December1st to 15thNight
9%18%7%28%28%6%
780
16th to endNight
12%20%10%29%21%5%
787
Page generated at 2017-12-21 04:04:45. Version ac04

Copyright 2017 A. Danko


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