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 2017-08-12.

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%
15817
30%
46344
24%
15766
68%
15766
38%
25009

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
71%
701
29%
1750
19%
697
72%
697
46%
991
August16th to endNight
77%
700
33%
1750
19%
700
80%
700
49%
961
September1st to 15thNight
73%
660
32%
1682
25%
660
74%
660
44%
962
September16th to endNight
75%
656
37%
1815
32%
656
80%
656
51%
900
October1st to 15thNight
71%
660
34%
1815
33%
660
73%
660
48%
954
October16th to endNight
72%
704
36%
2134
34%
704
79%
704
44%
1056
November1st to 15thNight
69%
700
34%
2275
36%
700
74%
700
45%
1038
November16th to endNight
63%
720
35%
2340
32%
720
72%
720
38%
1134
December1st to 15thNight
53%
720
32%
2340
27%
720
63%
720
30%
1254
December16th to endNight
50%
768
32%
2496
24%
768
62%
768
31%
1317

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%
47581
Night
6%6%23323347%56%
46549
TransparencyDay
21%37%19%26%22%
47276
Night
26%37%16%23%22%
46355
SeeingDay
5%11%17%36%24%4
5823
Night
7%15%5%24%34%12%
15826

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%
2114
16th to endDay
12112123410%68%
2100
September1st to 15thDay
131222235%7%67%
1947
16th to endDay
1312112247%71%
1815
October1st to 15thDay
5%313212346%64%
1812
16th to endDay
4223322346%65%
1736
November1st to 15thDay
3212213237%67%
1584
16th to endDay
5%313313348%63%
1620
December1st to 15thDay
6%41431335%8%55%
1620
16th to endDay
10%22242225%6%58%
1728
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
46%23323449%54%
1760
16th to endNight
241342435%10%57%
1750
September1st to 15thNight
3434424347%57%
1682
16th to endNight
36%22212338%64%
1815
October1st to 15thNight
3314323337%62%
1815
16th to endNight
5%412313337%63%
2134
November1st to 15thNight
3412213236%67%
2275
16th to endNight
35%13323337%62%
2340
December1st to 15thNight
7%5%14423346%56%
2340
16th to endNight
11%423212235%59%
2496

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%
2100
16th to endDay
12%3315%40%24%
2100
September1st to 15thDay
14%3413%34%29%
1947
16th to endDay
13%2217%33%29%
1815
October1st to 15thDay
21%27%22%24%23%
1812
16th to endDay
20%26%15%20%34%
1736
November1st to 15thDay
18%27%17%20%33%
1584
16th to endDay
20%38%15%21%30%
1620
December1st to 15thDay
27%410%16%18%22%
1620
16th to endDay
27%310%17%20%21%
1728
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
25%2216%33%18%
1750
16th to endNight
21%4313%33%24%
1750
September1st to 15thNight
25%348%30%27%
1682
16th to endNight
20%1313%31%29%
1815
October1st to 15thNight
22%35%17%29%21%
1815
16th to endNight
22%2413%23%33%
2134
November1st to 15thNight
19%25%17%20%35%
2275
16th to endNight
22%36%18%18%30%
2340
December1st to 15thNight
29%37%16%20%23%
2340
16th to endNight
28%39%16%21%20%
2496

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%
300
16th to endDay
15%436%42%8%
268
September1st to 15thDay
16%10%48%28%4
255
16th to endDay
17%12%45%24%7%
255
October1st to 15thDay
6%6%25%38%20%1
255
16th to endDay
46%18%39%24%6%
248
November1st to 15thDay
5%8%33%33%18%
90
16th to endDay
48%18%31%32%4
90
December1st to 15thDay
5%5%15%40%30%3
90
16th to endDay
10%6%21%34%25%2
96
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%24%
701
16th to endNight
5%9%9%42%32%
700
September1st to 15thNight
5%10%111%47%23%
660
16th to endNight
5%9%219%46%16%
656
October1st to 15thNight
5%10%5%25%41%12%
660
16th to endNight
6%10%423%38%16%
704
November1st to 15thNight
415%428%35%12%
700
16th to endNight
6%18%428%30%11%
720
December1st to 15thNight
10%19%7%28%28%6%
720
16th to endNight
12%20%10%29%21%4
768
Page generated at 2017-08-13 11:16:36. Version ac04

Copyright 2017 A. Danko


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