Laguna Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Laguna Beach clear sky chart from 2005-11-05 to 2017-09-18.

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
73%
16020
30%
46694
28%
15973
75%
15973
42%
25577

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
73%
717
29%
2294
30%
716
77%
716
42%
1189
January16th to endNight
67%
768
32%
2304
30%
768
71%
768
39%
1267
February1st to 15thNight
73%
697
34%
2103
35%
697
76%
697
44%
1104
February16th to endNight
63%
632
27%
1895
28%
632
66%
632
32%
1151
March1st to 15thNight
71%
720
29%
2160
31%
720
74%
720
43%
1155
March16th to endNight
72%
768
26%
2013
23%
768
74%
768
43%
1186
April1st to 15thNight
66%
719
26%
1799
18%
719
69%
719
42%
1093
April16th to endNight
73%
720
28%
1800
18%
720
75%
720
47%
1049
May1st to 15thNight
68%
614
25%
1694
18%
614
69%
614
36%
1051
May16th to endNight
68%
561
23%
1685
19%
561
69%
561
34%
1037
June1st to 15thNight
67%
540
20%
1620
18%
540
67%
540
29%
1054
June16th to endNight
71%
380
26%
1460
29%
380
71%
380
32%
756
July1st to 15thNight
73%
373
24%
1393
26%
373
73%
373
33%
723
July16th to endNight
78%
671
24%
1691
19%
629
78%
629
43%
989
August1st to 15thNight
78%
717
29%
1790
19%
713
78%
713
49%
1028
August16th to endNight
84%
764
36%
1910
25%
764
84%
764
58%
1024
September1st to 15thNight
82%
720
33%
1842
27%
720
82%
720
52%
1010
September16th to endNight
82%
667
38%
1847
38%
667
83%
667
56%
916
October1st to 15thNight
80%
660
35%
1815
35%
660
81%
660
53%
934
October16th to endNight
79%
704
37%
2128
40%
704
80%
704
48%
1065
November1st to 15thNight
81%
700
34%
2275
39%
700
82%
700
50%
1053
November16th to endNight
76%
720
35%
2340
39%
720
78%
720
44%
1160
December1st to 15thNight
69%
720
32%
2340
33%
720
73%
720
36%
1261
December16th to endNight
62%
768
32%
2496
29%
768
69%
768
37%
1322

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%61%
48075
Night
6%6%23323347%56%
46901
TransparencyDay
22%37%19%25%21%
47773
Night
28%26%16%23%22%
46704
SeeingDay
5%214%35%33%7%
5978
Night
8%15%26%41%15%
16033

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%413323347%57%
1641
16th to endDay
10%423222345%58%
1920
February1st to 15thDay
7%313223347%59%
1751
16th to endDay
10%42441345%7%52%
1579
March1st to 15thDay
431222436%10%58%
1800
16th to endDay
431231346%10%56%
2208
April1st to 15thDay
5%41222335%8%59%
2149
16th to endDay
3312212347%65%
2160
May1st to 15thDay
5%413212349%59%
2255
16th to endDay
45%23212349%60%
2429
June1st to 15thDay
6%6%233123411%52%
2340
16th to endDay
1312212339%67%
2493
July1st to 15thDay
24133134410%59%
2478
16th to endDay
231221345%9%63%
2357
August1st to 15thDay
2312111347%71%
2160
16th to endDay
12121235%9%69%
2292
September1st to 15thDay
1212212449%67%
2117
16th to endDay
1212212347%71%
1838
October1st to 15thDay
5%412313248%61%
1815
16th to endDay
4313212346%66%
1741
November1st to 15thDay
3212312246%68%
1584
16th to endDay
5%212313349%62%
1620
December1st to 15thDay
6%41422345%8%55%
1620
16th to endDay
10%313323237%57%
1728
January1st to 15thNight
6%413323337%59%
2294
16th to endNight
10%413322236%58%
2304
February1st to 15thNight
7%423322336%61%
2101
16th to endNight
12%6%25%333336%49%
1895
March1st to 15thNight
6%424323349%55%
2160
16th to endNight
5%6%1342445%10%51%
2013
April1st to 15thNight
9%6%32322247%54%
1799
16th to endNight
6%5%23213346%58%
1800
May1st to 15thNight
8%10%34323248%48%
1694
16th to endNight
7%10%24423448%46%
1684
June1st to 15thNight
9%13%343234410%39%
1620
16th to endNight
311%36%3145%411%44%
1460
July1st to 15thNight
410%3442436%11%44%
1476
16th to endNight
5%6%243345%6%11%46%
1808
August1st to 15thNight
36%243136%5%9%53%
1800
16th to endNight
2424212348%62%
1910
September1st to 15thNight
3414322447%60%
1842
16th to endNight
2423212337%66%
1847
October1st to 15thNight
4323313346%64%
1815
16th to endNight
6%5%12212347%62%
2128
November1st to 15thNight
3322312237%66%
2275
16th to endNight
5%423313246%62%
2340
December1st to 15thNight
8%414423346%55%
2340
16th to endNight
11%32331223460%
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
27%36%15%21%25%
1642
16th to endDay
29%37%16%16%27%
1920
February1st to 15thDay
25%35%17%24%22%
1751
16th to endDay
32%37%22%25%8%
1579
March1st to 15thDay
22%310%22%21%19%
1800
16th to endDay
23%414%25%19%12%
2208
April1st to 15thDay
24%39%28%22%10%
2149
16th to endDay
20%211%24%23%17%
2160
May1st to 15thDay
23%5%8%24%23%14%
2255
16th to endDay
23%39%29%26%7%
2432
June1st to 15thDay
27%36%18%30%13%
2340
16th to endDay
16%1311%29%36%
2493
July1st to 15thDay
21%2413%27%29%
2332
16th to endDay
19%39%23%27%16%
2211
August1st to 15thDay
15%1217%36%27%
2146
16th to endDay
13%2219%35%26%
2292
September1st to 15thDay
15%15%14%35%26%
2117
16th to endDay
16%1316%33%28%
1838
October1st to 15thDay
23%25%21%23%23%
1815
16th to endDay
19%35%16%20%33%
1741
November1st to 15thDay
19%27%18%19%32%
1584
16th to endDay
20%38%15%22%29%
1620
December1st to 15thDay
26%411%16%20%20%
1620
16th to endDay
29%39%17%21%18%
1728
January1st to 15thNight
26%27%12%20%28%
2294
16th to endNight
29%38%12%14%31%
2304
February1st to 15thNight
26%16%16%21%26%
2112
16th to endNight
37%36%14%23%15%
1895
March1st to 15thNight
26%38%20%21%20%
2160
16th to endNight
29%311%21%20%14%
2013
April1st to 15thNight
32%27%23%20%13%
1799
16th to endNight
26%38%22%22%16%
1800
May1st to 15thNight
36%27%19%19%14%
1695
16th to endNight
37%36%22%20%10%
1685
June1st to 15thNight
42%36%13%25%10%
1620
16th to endNight
33%1211%23%26%
1460
July1st to 15thNight
32%1312%24%24%
1393
16th to endNight
29%38%21%23%13%
1691
August1st to 15thNight
26%2216%32%18%
1790
16th to endNight
20%2314%31%27%
1910
September1st to 15thNight
23%2310%32%26%
1842
16th to endNight
20%1212%32%31%
1847
October1st to 15thNight
21%26%19%29%21%
1815
16th to endNight
22%2214%22%33%
2128
November1st to 15thNight
20%2416%19%36%
2275
16th to endNight
23%35%18%17%30%
2340
December1st to 15thNight
30%37%15%20%23%
2340
16th to endNight
28%39%15%22%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
20%5%13%42%17%1
120
16th to endDay
12%322%35%22%3
288
February1st to 15thDay
10%416%33%30%4
266
16th to endDay
11%5%28%31%20%2
238
March1st to 15thDay
6%424%34%23%6%
270
16th to endDay
5%7%20%38%25%3
288
April1st to 15thDay
6%5%27%40%15%4
269
16th to endDay
26%28%40%17%4
270
May1st to 15thDay
6%417%40%25%4
288
16th to endDay
6%415%44%23%6%
330
June1st to 15thDay
8%16%35%32%6%
315
16th to endDay
2430%51%11%
315
July1st to 15thDay
3423%52%13%
305
16th to endDay
4122%54%16%
327
August1st to 15thDay
4333%46%11%
315
16th to endDay
2227%53%14%
332
September1st to 15thDay
26%47%37%6%
315
16th to endDay
213%43%31%8%
264
October1st to 15thDay
5%122%40%27%3
255
16th to endDay
7%113%38%30%8%
242
November1st to 15thDay
47%25%41%21%
90
16th to endDay
36%16%36%31%5%
90
December1st to 15thDay
5%5%8%38%33%7%
90
16th to endDay
12%5%12%38%29%2
96
January1st to 15thNight
9%28%37%29%13%
720
16th to endNight
11%29%32%33%10%
768
February1st to 15thNight
9%15%33%36%12%
704
16th to endNight
14%18%37%29%8%
632
March1st to 15thNight
8%19%37%32%10%
720
16th to endNight
7%27%29%43%9%
768
April1st to 15thNight
11%38%34%35%7%
719
16th to endNight
7%37%33%38%9%
720
May1st to 15thNight
12%17%30%38%9%
615
16th to endNight
8%36%30%41%9%
563
June1st to 15thNight
12%15%30%41%7%
540
16th to endNight
8%113%61%13%
380
July1st to 15thNight
8%25%54%28%
373
16th to endNight
6%16%49%34%
671
August1st to 15thNight
5%110%54%27%
717
16th to endNight
5%7%50%36%
764
September1st to 15thNight
4113%53%25%
720
16th to endNight
4221%51%19%
667
October1st to 15thNight
41433%41%14%
660
16th to endNight
9%1324%42%19%
704
November1st to 15thNight
5%431%40%18%
700
16th to endNight
6%16%31%36%17%
720
December1st to 15thNight
10%26%34%35%10%
720
16th to endNight
13%410%33%28%8%
768
Page generated at 2017-09-19 04:32:26. Version ac04

Copyright 2017 A. Danko


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