Santa Barbara
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Santa Barbara clear sky chart from 2005-11-06 to 2024-03-28.

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
65%
24540
34%
80141
26%
24431
74%
24431
47%
38315

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 10thNight
50%
754
37%
4131
21%
736
64%
736
27%
1674
January11th to 20thNight
56%
758
34%
4025
26%
740
71%
740
25%
1942
January21st to endNight
49%
831
23%
4202
25%
814
64%
814
24%
2134
February1st to 10thNight
53%
760
35%
2284
27%
760
65%
760
41%
1199
February11th to 20thNight
51%
740
36%
2218
26%
740
66%
740
45%
1125
February21st to endNight
46%
628
28%
1884
20%
628
57%
628
38%
1024
March1st to 10thNight
51%
760
26%
2280
18%
760
63%
760
34%
1283
March11th to 20thNight
56%
760
27%
2099
19%
760
65%
760
40%
1183
March21st to endNight
52%
820
32%
2112
17%
820
64%
820
47%
1144
April1st to 10thNight
55%
720
33%
1800
17%
720
63%
720
48%
1001
April11th to 20thNight
56%
711
36%
1779
15%
711
66%
711
55%
921
April21st to endNight
59%
720
33%
1800
13%
720
68%
720
60%
901
May1st to 10thNight
60%
720
31%
1800
16%
720
66%
720
60%
912
May11th to 20thNight
67%
600
30%
1664
18%
600
72%
600
60%
782
May21st to endNight
65%
514
31%
1678
22%
514
72%
514
54%
726
June1st to 10thNight
73%
360
31%
1440
32%
360
78%
360
44%
595
June11th to 20thNight
80%
360
34%
1440
36%
360
85%
360
63%
498
June21st to endNight
81%
360
37%
1440
42%
360
87%
360
68%
469
July1st to 10thNight
90%
350
36%
1400
43%
350
92%
350
69%
459
July11th to 20thNight
89%
471
35%
1515
34%
471
89%
471
67%
596
July21st to endNight
88%
617
38%
1699
31%
583
89%
583
65%
748
August1st to 10thNight
85%
716
35%
1780
23%
712
86%
712
75%
832
August11th to 20thNight
88%
712
39%
1780
24%
712
89%
712
80%
809
August21st to endNight
90%
792
43%
1980
29%
792
91%
792
81%
883
September1st to 10thNight
80%
720
42%
1800
31%
720
82%
720
75%
839
September11th to 20thNight
83%
720
46%
1846
38%
720
86%
720
78%
827
September21st to endNight
82%
720
43%
1980
38%
720
87%
720
77%
833
October1st to 10thNight
75%
720
38%
2066
34%
720
83%
720
66%
905
October11th to 20thNight
68%
720
40%
2160
34%
720
79%
720
59%
962
October21st to endNight
68%
792
42%
2376
38%
792
79%
792
60%
1044
November1st to 10thNight
64%
740
38%
2330
31%
740
77%
740
56%
1024
November11th to 20thNight
64%
760
38%
2470
31%
760
77%
760
52%
1103
November21st to endNight
59%
760
35%
2470
29%
760
71%
760
46%
1185
December1st to 10thNight
58%
760
34%
2470
27%
760
70%
760
40%
1251
December11th to 20thNight
50%
760
27%
3178
24%
759
63%
759
23%
1905
December21st to endNight
51%
834
20%
4765
26%
817
65%
817
19%
2597

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
5%31332435%7%65%
78985
Night
6%313323346%65%
81041
TransparencyDay
18%5%9%21%27%20%
78706
Night
19%47%18%28%24%
80842
SeeingDay
6%9%23%38%20%4
14747
Night
6%5%18%32%30%9%
24561

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 10thDay
7%212322347%67%
2669
11th to 20thDay
10%41332436%7%56%
2860
21st to endDay
12%4233246%5%9%49%
3146
February1st to 10thDay
11%413213245%62%
1893
11th to 20thDay
8%21232445%8%61%
1850
21st to endDay
9%412325%346%59%
1570
March1st to 10thDay
9%3243346%5%7%55%
1900
11th to 20thDay
8%32332446%8%58%
2078
21st to endDay
5%213324347%64%
2397
April1st to 10thDay
6%21332445%8%61%
2160
11th to 20thDay
3223323346%68%
2129
21st to endDay
331322335%7%68%
2160
May1st to 10thDay
5%31322445%8%64%
2160
11th to 20thDay
3313224347%67%
2229
21st to endDay
431321335%7%67%
2592
June1st to 10thDay
45%25%325%347%62%
2520
11th to 20thDay
2413225%346%68%
2520
21st to endDay
2212225%246%72%
2520
July1st to 10thDay
221423445%7%67%
2520
11th to 20thDay
2213325%345%70%
2389
21st to endDay
2213335%45%8%64%
2517
August1st to 10thDay
2313325%447%65%
2149
11th to 20thDay
2212225%347%69%
2122
21st to endDay
2212223346%72%
2376
September1st to 10thDay
2312222347%71%
2160
11th to 20thDay
3312222246%74%
2112
21st to endDay
1122222245%77%
1980
October1st to 10thDay
3212222345%74%
1890
11th to 20thDay
321332324475%
1800
21st to endDay
2212223336%74%
1980
November1st to 10thDay
321231335%6%72%
1746
11th to 20thDay
4213223445%69%
1710
21st to endDay
411432435%7%67%
1710
December1st to 10thDay
8%414323446%61%
1710
11th to 20thDay
21%41442245%6%46%
1967
21st to endDay
14%5%135%2445%7%49%
2794
January1st to 10thNight
9%313322345%65%
4277
11th to 20thNight
9%425%424447%55%
4110
21st to endNight
13%423423448%54%
4521
February1st to 10thNight
10%423223246%63%
2284
11th to 20thNight
8%312313346%66%
2218
21st to endNight
11%31342333462%
1884
March1st to 10thNight
9%4133245%6%8%55%
2280
11th to 20thNight
8%21432445%8%58%
2099
21st to endNight
7%312313347%67%
2112
April1st to 10thNight
6%32332335%8%62%
1800
11th to 20thNight
4313212345%72%
1779
21st to endNight
3212223347%71%
1800
May1st to 10thNight
5%313224347%67%
1800
11th to 20thNight
2325%325%246%67%
1663
21st to endNight
4412214235%72%
1678
June1st to 10thNight
14145%35%35%8%61%
1440
11th to 20thNight
2312225%347%69%
1440
21st to endNight
2113314245%74%
1440
July1st to 10thNight
11342326%8%70%
1440
11th to 20thNight
11331345%6%72%
1566
21st to endNight
1212325%45%6%69%
1799
August1st to 10thNight
2212314446%72%
1790
11th to 20thNight
123224437%71%
1780
21st to endNight
111221332481%
1980
September1st to 10thNight
341222223475%
1800
11th to 20thNight
2212113225%79%
1846
21st to endNight
2112223235%78%
1980
October1st to 10thNight
3113212245%77%
2066
11th to 20thNight
4213322245%72%
2160
21st to endNight
332221222477%
2376
November1st to 10thNight
3212323336%72%
2330
11th to 20thNight
3312213346%72%
2470
21st to endNight
5%323322446%68%
2470
December1st to 10thNight
8%213323346%63%
2470
11th to 20thNight
20%42332335%8%46%
3231
21st to endNight
15%5%2443445%6%49%
4862

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 10thDay
20%5%5%28%33%9%
2669
11th to 20thDay
27%7%15%15%22%13%
2860
21st to endDay
31%7%10%19%24%11%
3146
February1st to 10thDay
26%45%19%25%20%
1893
11th to 20thDay
22%6%7%21%26%17%
1860
21st to endDay
26%6%8%21%25%14%
1570
March1st to 10thDay
29%9%7%20%22%13%
1900
11th to 20thDay
25%6%14%20%22%13%
2078
21st to endDay
22%6%11%28%24%9%
2397
April1st to 10thDay
22%8%14%23%22%12%
2160
11th to 20thDay
18%6%9%25%30%13%
2132
21st to endDay
15%6%14%23%33%10%
2160
May1st to 10thDay
18%6%15%19%28%13%
2160
11th to 20thDay
13%7%13%27%28%13%
2232
21st to endDay
14%5%14%33%27%8%
2592
June1st to 10thDay
17%6%14%21%28%13%
2520
11th to 20thDay
10%410%21%32%23%
2520
21st to endDay
9%28%17%30%34%
2520
July1st to 10thDay
9%26%24%25%34%
2451
11th to 20thDay
12%311%21%30%23%
2317
21st to endDay
14%211%26%29%17%
2377
August1st to 10thDay
13%28%22%29%26%
2135
11th to 20thDay
7%110%24%31%27%
2122
21st to endDay
9%16%22%32%29%
2376
September1st to 10thDay
9%27%18%27%38%
2160
11th to 20thDay
8%29%18%36%28%
2112
21st to endDay
8%29%18%34%29%
1980
October1st to 10thDay
13%49%18%26%30%
1890
11th to 20thDay
14%36%18%30%29%
1800
21st to endDay
14%37%15%28%33%
1980
November1st to 10thDay
15%49%18%29%26%
1746
11th to 20thDay
18%5%8%16%26%29%
1710
21st to endDay
19%47%16%28%25%
1710
December1st to 10thDay
26%5%7%18%26%19%
1710
11th to 20thDay
40%6%5%16%21%12%
1967
21st to endDay
34%6%8%22%21%9%
2794
January1st to 10thNight
23%5%5%20%35%12%
4277
11th to 20thNight
28%7%9%17%24%15%
4110
21st to endNight
30%5%6%18%27%14%
4521
February1st to 10thNight
26%46%17%24%24%
2284
11th to 20thNight
20%5%5%19%31%19%
2219
21st to endNight
26%5%7%17%27%18%
1884
March1st to 10thNight
28%7%9%19%25%12%
2280
11th to 20thNight
24%8%10%19%22%16%
2099
21st to endNight
20%5%9%24%29%13%
2112
April1st to 10thNight
22%5%10%25%25%13%
1800
11th to 20thNight
15%5%8%23%30%19%
1779
21st to endNight
12%5%12%24%35%13%
1800
May1st to 10thNight
14%411%24%29%17%
1800
11th to 20thNight
13%5%12%22%31%17%
1664
21st to endNight
14%411%25%34%13%
1678
June1st to 10thNight
16%7%12%17%32%17%
1440
11th to 20thNight
9%49%17%29%32%
1440
21st to endNight
8%27%12%27%44%
1440
July1st to 10thNight
8%2412%27%47%
1400
11th to 20thNight
10%36%18%26%38%
1515
21st to endNight
12%35%22%30%27%
1699
August1st to 10thNight
11%1315%27%43%
1780
11th to 20thNight
7%27%14%31%39%
1780
21st to endNight
7%1313%34%42%
1980
September1st to 10thNight
10%1414%22%49%
1800
11th to 20thNight
8%26%13%34%37%
1846
21st to endNight
7%26%10%39%36%
1980
October1st to 10thNight
11%36%17%27%36%
2066
11th to 20thNight
15%26%16%27%34%
2160
21st to endNight
13%35%10%29%40%
2376
November1st to 10thNight
15%36%16%31%29%
2330
11th to 20thNight
16%46%14%27%33%
2470
21st to endNight
21%46%17%25%27%
2470
December1st to 10thNight
24%45%17%25%25%
2470
11th to 20thNight
39%5%8%15%20%14%
3231
21st to endNight
35%6%7%18%23%10%
4862

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 10thDay
17%13%28%28%14%
258
11th to 20thDay
15%11%26%32%13%2
370
21st to endDay
11%10%35%31%11%2
407
February1st to 10thDay
15%13%27%27%14%4
457
11th to 20thDay
11%16%31%28%12%2
455
21st to endDay
13%16%31%29%10%2
382
March1st to 10thDay
14%20%31%26%9%
460
11th to 20thDay
13%18%31%29%8%1
460
21st to endDay
11%19%33%31%6%
491
April1st to 10thDay
10%13%31%32%12%2
420
11th to 20thDay
6%16%33%34%10%2
412
21st to endDay
5%13%32%35%12%4
420
May1st to 10thDay
11%9%32%29%16%3
423
11th to 20thDay
5%9%28%37%19%3
448
21st to endDay
7%10%29%35%16%2
485
June1st to 10thDay
5%5%21%44%22%3
450
11th to 20thDay
25%20%41%26%6%
450
21st to endDay
1316%45%27%7%
450
July1st to 10thDay
19%50%34%6%
446
11th to 20thDay
21444%41%8%
444
21st to endDay
28%42%38%9%
487
August1st to 10thDay
2111%50%29%8%
447
11th to 20thDay
118%47%38%5%
437
21st to endDay
219%51%34%4
495
September1st to 10thDay
2215%50%26%4
450
11th to 20thDay
2322%49%22%2
450
21st to endDay
15%21%49%22%3
450
October1st to 10thDay
28%22%48%19%1
450
11th to 20thDay
25%27%45%17%4
450
21st to endDay
47%25%36%24%4
495
November1st to 10thDay
410%23%40%19%5%
342
11th to 20thDay
7%6%29%35%19%4
270
21st to endDay
6%11%24%37%18%5%
270
December1st to 10thDay
8%13%31%31%15%2
270
11th to 20thDay
10%12%26%32%15%6%
198
21st to endDay
14%19%29%28%9%2
198
January1st to 10thNight
13%6%24%28%18%10%
760
11th to 20thNight
10%424%32%23%6%
760
21st to endNight
12%7%27%32%16%6%
836
February1st to 10thNight
13%8%21%30%23%5%
760
11th to 20thNight
9%7%28%30%18%9%
744
21st to endNight
12%8%30%28%18%4
628
March1st to 10thNight
12%9%22%36%18%2
760
11th to 20thNight
9%8%22%33%24%5%
760
21st to endNight
10%8%27%33%19%4
820
April1st to 10thNight
8%6%25%36%21%4
720
11th to 20thNight
5%8%25%34%24%5%
711
21st to endNight
38%26%33%22%8%
720
May1st to 10thNight
46%23%33%28%6%
720
11th to 20thNight
35%17%36%33%7%
600
21st to endNight
37%17%34%31%7%
516
June1st to 10thNight
1413%40%36%7%
360
11th to 20thNight
1112%32%43%12%
360
21st to endNight
119%30%48%12%
360
July1st to 10thNight
329%52%16%
350
11th to 20thNight
121%52%25%
471
21st to endNight
1324%46%26%
617
August1st to 10thNight
216%26%49%17%
716
11th to 20thNight
1427%48%19%
712
21st to endNight
1225%54%18%
792
September1st to 10thNight
219%28%46%15%
720
11th to 20thNight
28%39%39%12%
720
21st to endNight
1211%37%38%11%
720
October1st to 10thNight
3215%41%33%5%
720
11th to 20thNight
5%218%36%30%9%
720
21st to endNight
4417%34%31%10%
792
November1st to 10thNight
45%21%34%27%8%
740
11th to 20thNight
6%422%34%27%7%
760
21st to endNight
7%424%35%22%8%
760
December1st to 10thNight
9%6%22%33%23%7%
760
11th to 20thNight
13%8%23%33%19%4
760
21st to endNight
10%9%25%35%16%5%
836
Page generated at 2024-03-24 20:37:03. Version ac07

Copyright © 2024 Attilla Danko.


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