Huntington Beach State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huntington Beach State Park clear sky chart from 2005-11-05 to 2018-03-21.

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
54%
16782
21%
49135
15%
16740
60%
16740
28%
31066

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
38%
779
21%
2522
11%
776
51%
776
22%
1562
January16th to endNight
36%
832
24%
2704
16%
832
49%
832
27%
1643
February1st to 15thNight
38%
764
20%
2482
13%
761
50%
761
26%
1508
February16th to endNight
39%
683
25%
1935
14%
683
51%
683
29%
1237
March1st to 15thNight
45%
780
26%
2145
16%
780
54%
780
34%
1318
March16th to endNight
49%
792
22%
2178
14%
792
55%
792
32%
1362
April1st to 15thNight
53%
718
24%
1862
14%
718
58%
718
37%
1155
April16th to endNight
57%
720
23%
1800
14%
720
60%
720
37%
1129
May1st to 15thNight
59%
616
20%
1697
13%
616
61%
616
33%
1056
May16th to endNight
69%
561
18%
1684
15%
561
70%
561
32%
1020
June1st to 15thNight
69%
540
14%
1620
12%
540
69%
540
27%
1046
June16th to endNight
71%
540
13%
1620
12%
540
72%
540
28%
1030
July1st to 15thNight
72%
510
12%
1530
11%
510
73%
510
26%
992
July16th to endNight
73%
564
12%
1595
10%
531
75%
531
26%
1057
August1st to 15thNight
72%
542
14%
1612
12%
539
71%
539
23%
1105
August16th to endNight
67%
764
14%
1910
11%
764
67%
764
23%
1412
September1st to 15thNight
67%
720
18%
1848
15%
720
68%
720
26%
1314
September16th to endNight
57%
717
15%
1995
14%
717
58%
717
21%
1457
October1st to 15thNight
59%
720
25%
2160
26%
720
63%
720
30%
1344
October16th to endNight
56%
768
33%
2304
28%
768
66%
768
37%
1289
November1st to 15thNight
56%
760
29%
2281
23%
760
65%
760
38%
1286
November16th to endNight
50%
780
27%
2412
19%
780
60%
780
31%
1418
December1st to 15thNight
42%
780
22%
2535
14%
780
52%
780
24%
1595
December16th to endNight
41%
832
22%
2704
16%
832
50%
832
22%
1731

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
10%5%244345%6%8%43%
49713
Night
11%5%245%3445%8%44%
49332
TransparencyDay
36%7%15%20%15%4
49414
Night
36%7%13%19%16%6%
49135
SeeingDay
12%215%25%30%13%
6516
Night
13%419%29%26%6%
16786

By Month

Percentage Cloud Cover SE (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
14%6%25%423446%45%
1746
16th to endDay
14%5%44424436%45%
1872
February1st to 15thDay
15%6%26%423345%44%
1710
16th to endDay
13%5%25%423446%47%
1821
March1st to 15thDay
11%5%24323446%50%
2145
16th to endDay
13%415%4245%5%7%45%
2173
April1st to 15thDay
10%41332345%6%53%
2086
16th to endDay
6%3235%34448%52%
2160
May1st to 15thDay
8%42443446%8%47%
2264
16th to endDay
8%4243346%7%9%45%
2431
June1st to 15thDay
8%324436%6%9%12%37%
2340
16th to endDay
5%315%5%45%6%9%10%39%
2340
July1st to 15thDay
6%325%5%37%7%9%12%34%
2340
16th to endDay
7%5%25%5%37%6%9%12%34%
2465
August1st to 15thDay
10%425%6%45%8%10%12%29%
2325
16th to endDay
12%6%36%5%36%8%8%10%29%
2292
September1st to 15thDay
12%4134346%8%10%39%
2109
16th to endDay
14%7%26%7%45%5%6%7%33%
1965
October1st to 15thDay
15%324423346%50%
1800
16th to endDay
8%424323345%57%
1920
November1st to 15thDay
12%314323345%54%
1907
16th to endDay
10%435%423345%52%
1875
December1st to 15thDay
13%6%35%5%245%5%7%40%
1755
16th to endDay
14%6%25%324448%42%
1872
January1st to 15thNight
10%6%25%5%35%5%45%45%
2522
16th to endNight
13%5%25%424346%46%
2704
February1st to 15thNight
16%5%14323346%46%
2473
16th to endNight
12%6%25%435%447%44%
1935
March1st to 15thNight
11%41442445%6%49%
2145
16th to endNight
12%42432445%6%48%
2178
April1st to 15thNight
9%5%2443435%8%49%
1862
16th to endNight
8%4245%3446%8%48%
1800
May1st to 15thNight
8%5%235%3445%7%48%
1696
16th to endNight
8%4144245%6%10%45%
1682
June1st to 15thNight
8%4245%35%6%7%12%39%
1620
16th to endNight
5%325%5%35%6%8%14%39%
1620
July1st to 15thNight
6%4346%36%7%7%11%37%
1620
16th to endNight
5%5%25%6%37%6%8%11%36%
1703
August1st to 15thNight
8%4246%46%8%9%13%31%
1623
16th to endNight
10%6%246%36%7%9%11%29%
1910
September1st to 15thNight
10%5%26%7%347%6%10%36%
1848
16th to endNight
16%7%36%5%35%5%5%8%31%
1995
October1st to 15thNight
14%5%24324345%48%
2160
16th to endNight
8%424433235%56%
2304
November1st to 15thNight
10%413323335%56%
2281
16th to endNight
11%42442335%6%50%
2412
December1st to 15thNight
15%6%245%2445%6%42%
2535
16th to endNight
15%5%25%5%2445%7%40%
2704

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
39%5%11%16%21%5%
1747
16th to endDay
40%38%18%21%7%
1872
February1st to 15thDay
42%47%20%20%5%
1712
16th to endDay
38%48%23%19%6%
1821
March1st to 15thDay
35%411%19%20%8%
2145
16th to endDay
37%7%12%20%17%4
2174
April1st to 15thDay
29%5%13%24%21%5%
2086
16th to endDay
29%6%13%21%20%7%
2160
May1st to 15thDay
32%8%15%26%15%1
2264
16th to endDay
32%8%21%24%12%
2435
June1st to 15thDay
34%11%21%22%9%
2340
16th to endDay
34%12%21%23%7%
2340
July1st to 15thDay
35%13%21%22%5%1
2201
16th to endDay
35%12%24%20%5%
2310
August1st to 15thDay
40%12%21%20%4
2312
16th to endDay
43%13%22%15%5%
2292
September1st to 15thDay
35%11%18%17%14%3
2109
16th to endDay
47%8%12%16%12%2
1965
October1st to 15thDay
35%5%10%21%23%4
1800
16th to endDay
28%38%20%28%10%
1920
November1st to 15thDay
32%39%19%24%9%
1907
16th to endDay
34%39%18%23%10%
1875
December1st to 15thDay
42%6%11%18%14%7%
1755
16th to endDay
40%5%13%19%15%5%
1872
January1st to 15thNight
40%49%16%21%7%
2522
16th to endNight
39%37%18%21%9%
2704
February1st to 15thNight
39%38%18%19%9%
2482
16th to endNight
39%49%20%18%7%
1935
March1st to 15thNight
34%5%11%20%20%9%
2145
16th to endNight
35%6%12%22%17%5%
2178
April1st to 15thNight
33%412%21%20%7%
1862
16th to endNight
31%7%13%20%20%7%
1800
May1st to 15thNight
33%7%14%22%19%2
1697
16th to endNight
31%9%18%28%11%1
1684
June1st to 15thNight
36%10%21%23%8%
1620
16th to endNight
33%12%22%23%7%
1620
July1st to 15thNight
35%12%25%17%8%
1530
16th to endNight
36%12%22%22%5%
1595
August1st to 15thNight
38%14%19%20%6%
1612
16th to endNight
42%14%19%19%4
1910
September1st to 15thNight
41%10%15%15%13%2
1848
16th to endNight
47%9%12%16%11%2
1995
October1st to 15thNight
36%6%9%19%21%6%
2160
16th to endNight
30%37%17%26%13%
2304
November1st to 15thNight
30%39%18%24%12%
2281
16th to endNight
33%5%10%17%21%11%
2412
December1st to 15thNight
41%5%12%16%16%7%
2535
16th to endNight
42%5%11%18%14%6%
2704

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%6%28%33%12%
135
16th to endDay
16%127%42%10%2
144
February1st to 15thDay
16%331%38%9%
135
16th to endDay
12%6%31%35%14%1
257
March1st to 15thDay
12%6%29%33%16%
330
16th to endDay
12%325%34%20%2
311
April1st to 15thDay
12%5%24%27%22%7%
270
16th to endDay
7%316%25%35%10%
270
May1st to 15thDay
7%123%36%23%6%
288
16th to endDay
10%11%19%34%23%
331
June1st to 15thDay
8%15%24%39%20%
315
16th to endDay
7%1418%43%24%
315
July1st to 15thDay
6%1414%46%24%
305
16th to endDay
7%215%50%23%
326
August1st to 15thDay
15%1217%41%21%
313
16th to endDay
15%5%12%35%29%
332
September1st to 15thDay
13%15%22%38%18%
315
16th to endDay
17%19%23%34%13%
314
October1st to 15thDay
19%115%22%26%14%
315
16th to endDay
9%219%25%28%14%
336
November1st to 15thDay
15%5%18%24%27%9%
325
16th to endDay
10%5%21%29%25%7%
255
December1st to 15thDay
23%21%29%21%2
135
16th to endDay
18%326%33%16%1
144
January1st to 15thNight
14%11%29%29%13%1
780
16th to endNight
15%8%34%32%8%
832
February1st to 15thNight
18%8%29%35%7%
764
16th to endNight
14%6%32%34%11%
683
March1st to 15thNight
14%430%36%13%
780
16th to endNight
14%326%33%19%2
792
April1st to 15thNight
11%6%22%32%22%4
718
16th to endNight
9%421%32%27%4
720
May1st to 15thNight
9%319%35%27%4
617
16th to endNight
10%10%26%34%16%
563
June1st to 15thNight
10%17%28%40%12%
540
16th to endNight
7%16%25%42%17%
540
July1st to 15thNight
7%15%22%48%13%
510
16th to endNight
6%1424%53%9%
564
August1st to 15thNight
10%1221%50%13%
542
16th to endNight
12%1418%42%20%
764
September1st to 15thNight
12%15%23%46%11%
720
16th to endNight
21%18%25%32%10%
717
October1st to 15thNight
17%213%28%28%8%
720
16th to endNight
10%5%20%28%27%7%
768
November1st to 15thNight
12%322%33%22%5%
760
16th to endNight
12%7%23%31%20%4
780
December1st to 15thNight
18%5%24%31%16%2
780
16th to endNight
18%6%27%33%13%1
832
Page generated at 2018-03-22 11:34:26. Version ac04

Copyright 2018 A. Danko


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