Santa Clarita
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Santa Clarita clear sky chart from 2005-11-05 to 2018-02-14.

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
74%
16396
35%
48712
30%
16345
79%
16345
54%
23102

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
58%
780
29%
2667
26%
776
68%
776
40%
1307
January16th to endNight
57%
832
35%
2600
27%
832
69%
832
42%
1323
February1st to 15thNight
65%
755
36%
2271
31%
752
74%
752
48%
1143
February16th to endNight
59%
632
30%
1895
29%
632
65%
632
38%
1065
March1st to 15thNight
65%
720
29%
2160
26%
720
73%
720
48%
1076
March16th to endNight
70%
768
30%
1994
23%
768
76%
768
51%
1077
April1st to 15thNight
67%
719
31%
1799
19%
719
72%
719
53%
987
April16th to endNight
70%
720
33%
1800
16%
720
75%
720
62%
913
May1st to 15thNight
73%
632
30%
1712
20%
632
75%
632
53%
888
May16th to endNight
77%
561
31%
1685
25%
561
79%
561
59%
763
June1st to 15thNight
85%
417
32%
1497
34%
417
87%
417
59%
593
June16th to endNight
96%
360
41%
1440
51%
360
96%
360
76%
438
July1st to 15thNight
93%
340
36%
1360
43%
340
93%
340
64%
465
July16th to endNight
91%
603
36%
1625
30%
563
92%
563
66%
715
August1st to 15thNight
92%
717
37%
1790
24%
713
92%
713
77%
827
August16th to endNight
95%
764
46%
1910
31%
764
95%
764
82%
852
September1st to 15thNight
92%
720
41%
1815
33%
720
92%
720
72%
869
September16th to endNight
92%
716
47%
1980
46%
716
93%
716
78%
827
October1st to 15thNight
79%
720
36%
2022
35%
720
83%
720
60%
961
October16th to endNight
76%
768
43%
2316
42%
768
81%
768
57%
1062
November1st to 15thNight
74%
760
34%
2470
33%
760
82%
760
55%
1097
November16th to endNight
70%
780
39%
2535
37%
780
78%
780
52%
1151
December1st to 15thNight
61%
780
34%
2535
28%
780
71%
780
40%
1265
December16th to endNight
56%
832
34%
2834
28%
832
67%
832
36%
1438

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
4212212235%70%
49346
Night
4212212235%70%
48913
TransparencyDay
17%36%16%28%28%
49038
Night
17%36%16%27%28%
48722
SeeingDay
5%8%27%39%14%4
6432
Night
5%212%35%35%8%
16404

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
8%313323246%61%
1598
16th to endDay
10%423212335%58%
1973
February1st to 15thDay
7%222322346%62%
1883
16th to endDay
9%424333245%55%
1579
March1st to 15thDay
5%31322345%8%61%
1800
16th to endDay
5%32332245%8%58%
2226
April1st to 15thDay
5%413323236%63%
2149
16th to endDay
4211212236%70%
2160
May1st to 15thDay
3312212336%69%
2235
16th to endDay
2312211246%71%
2429
June1st to 15thDay
3312112235%72%
2460
16th to endDay
111111386%
2520
July1st to 15thDay
11211223477%
2520
16th to endDay
211222245%75%
2424
August1st to 15thDay
1111122483%
2160
16th to endDay
11112384%
2292
September1st to 15thDay
1111122383%
2145
16th to endDay
1111121283%
1980
October1st to 15thDay
421111224473%
1937
16th to endDay
21221233472%
1908
November1st to 15thDay
3312222245%68%
1719
16th to endDay
4313313348%62%
1755
December1st to 15thDay
5%31232345%9%58%
1755
16th to endDay
9%322414435%57%
1739
January1st to 15thNight
7%423322347%59%
2667
16th to endNight
8%413212236%61%
2600
February1st to 15thNight
5%323312245%64%
2269
16th to endNight
10%423323345%55%
1895
March1st to 15thNight
431221335%8%62%
2160
16th to endNight
5%22314448%63%
1994
April1st to 15thNight
6%312312235%66%
1799
16th to endNight
3311111246%72%
1800
May1st to 15thNight
3312212346%69%
1712
16th to endNight
1212212236%73%
1684
June1st to 15thNight
111112328%73%
1497
16th to endNight
1111388%
1440
July1st to 15thNight
12211235%78%
1440
16th to endNight
111212245%75%
1739
August1st to 15thNight
1111112482%
1800
16th to endNight
111112385%
1910
September1st to 15thNight
21111121481%
1815
16th to endNight
111112385%
1980
October1st to 15thNight
311211223374%
2022
16th to endNight
32211222475%
2316
November1st to 15thNight
321221323471%
2470
16th to endNight
4212213346%67%
2535
December1st to 15thNight
6%314322336%61%
2535
16th to endNight
10%313213336%60%
2834

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
24%37%14%25%24%
1598
16th to endDay
27%37%17%18%25%
1973
February1st to 15thDay
22%35%14%25%27%
1883
16th to endDay
30%46%16%29%11%
1579
March1st to 15thDay
22%39%22%21%21%
1800
16th to endDay
22%5%11%24%19%16%
2226
April1st to 15thDay
22%410%22%25%13%
2149
16th to endDay
16%310%21%30%18%
2160
May1st to 15thDay
17%49%20%26%21%
2235
16th to endDay
16%39%25%32%12%
2432
June1st to 15thDay
16%28%16%32%22%
2460
16th to endDay
7%138%35%43%
2520
July1st to 15thDay
12%248%28%42%
2371
16th to endDay
12%36%19%30%27%
2276
August1st to 15thDay
8%1212%34%40%
2146
16th to endDay
6%1311%38%38%
2292
September1st to 15thDay
8%25%12%29%42%
2145
16th to endDay
9%1212%34%39%
1980
October1st to 15thDay
15%25%16%26%32%
1937
16th to endDay
15%35%11%23%40%
1908
November1st to 15thDay
19%25%15%27%28%
1719
16th to endDay
21%35%14%22%33%
1755
December1st to 15thDay
22%48%15%23%25%
1755
16th to endDay
28%46%16%23%19%
1739
January1st to 15thNight
25%36%16%25%23%
2667
16th to endNight
25%37%15%19%29%
2600
February1st to 15thNight
21%36%14%24%28%
2280
16th to endNight
31%36%16%28%14%
1895
March1st to 15thNight
20%410%19%24%20%
2160
16th to endNight
19%5%11%22%23%16%
1994
April1st to 15thNight
21%210%27%23%13%
1799
16th to endNight
13%49%24%29%19%
1800
May1st to 15thNight
18%5%8%19%30%17%
1713
16th to endNight
14%310%26%30%14%
1685
June1st to 15thNight
11%411%16%32%23%
1497
16th to endNight
5%139%32%46%
1440
July1st to 15thNight
10%1412%25%45%
1360
16th to endNight
12%25%21%28%30%
1625
August1st to 15thNight
8%129%36%41%
1790
16th to endNight
7%210%39%39%
1910
September1st to 15thNight
10%239%29%44%
1815
16th to endNight
7%1211%36%40%
1980
October1st to 15thNight
15%3416%29%31%
2022
16th to endNight
16%2411%22%42%
2316
November1st to 15thNight
16%26%15%25%32%
2470
16th to endNight
18%26%16%24%32%
2535
December1st to 15thNight
24%37%14%21%28%
2535
16th to endNight
26%37%15%25%20%
2834

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
15%10%43%25%5%
136
16th to endDay
14%14%34%28%7%
327
February1st to 15thDay
6%13%33%32%11%2
320
16th to endDay
13%17%35%28%4
238
March1st to 15thDay
7%20%30%27%12%1
270
16th to endDay
7%13%39%29%9%1
288
April1st to 15thDay
10%14%39%24%7%2
269
16th to endDay
422%38%27%5%1
270
May1st to 15thDay
7%11%33%33%10%3
288
16th to endDay
6%11%33%32%13%3
330
June1st to 15thDay
5%6%23%45%13%4
315
16th to endDay
118%42%25%11%
315
July1st to 15thDay
112%47%26%10%
305
16th to endDay
37%50%28%10%
327
August1st to 15thDay
312%56%19%8%
315
16th to endDay
12%52%21%12%
332
September1st to 15thDay
2222%51%16%5%
315
16th to endDay
2326%48%15%3
315
October1st to 15thDay
28%34%40%12%1
315
16th to endDay
46%28%40%18%1
324
November1st to 15thDay
5%5%21%37%22%7%
135
16th to endDay
38%32%37%15%2
135
December1st to 15thDay
5%8%26%43%15%
135
16th to endDay
9%12%29%33%12%2
113
January1st to 15thNight
7%421%45%17%3
780
16th to endNight
11%421%41%17%3
832
February1st to 15thNight
7%118%42%24%5%
760
16th to endNight
13%318%38%21%3
632
March1st to 15thNight
5%5%18%41%22%5%
720
16th to endNight
5%414%43%28%3
768
April1st to 15thNight
7%415%42%27%3
719
16th to endNight
4318%36%30%6%
720
May1st to 15thNight
6%214%38%34%4
633
16th to endNight
3311%41%36%4
563
June1st to 15thNight
17%37%47%4
417
16th to endNight
30%61%6%
360
July1st to 15thNight
15%71%11%
340
16th to endNight
1110%68%17%
603
August1st to 15thNight
1117%63%14%
717
16th to endNight
114%60%22%
764
September1st to 15thNight
3121%53%19%
720
16th to endNight
431%47%15%
716
October1st to 15thNight
419%40%38%5%
720
16th to endNight
5%113%34%33%10%
768
November1st to 15thNight
4114%43%29%6%
760
16th to endNight
6%117%39%27%6%
780
December1st to 15thNight
9%5%17%41%21%4
780
16th to endNight
13%7%18%40%17%3
832
Page generated at 2018-02-15 07:58:39. Version ac04

Copyright 2018 A. Danko


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