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 2017-04-07.

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%
15270
35%
45335
30%
15219
79%
15219
54%
21605

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
57%
720
30%
2461
26%
716
68%
716
41%
1186
January16th to endNight
56%
768
34%
2400
26%
768
68%
768
40%
1244
February1st to 15thNight
64%
699
35%
2103
30%
696
73%
696
47%
1070
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%
687
32%
1719
20%
687
72%
687
53%
947
April16th to endNight
70%
660
31%
1650
15%
660
75%
660
61%
846
May1st to 15thNight
72%
579
31%
1569
21%
579
74%
579
52%
819
May16th to endNight
77%
513
29%
1541
23%
513
79%
513
59%
697
June1st to 15thNight
85%
382
34%
1372
36%
382
88%
382
59%
540
June16th to endNight
96%
330
39%
1320
47%
330
96%
330
75%
407
July1st to 15thNight
93%
310
37%
1240
45%
310
93%
310
64%
424
July16th to endNight
91%
557
34%
1495
28%
517
91%
517
66%
662
August1st to 15thNight
92%
657
40%
1640
26%
653
92%
653
78%
755
August16th to endNight
95%
700
43%
1750
29%
700
95%
700
82%
783
September1st to 15thNight
92%
660
43%
1664
35%
660
92%
660
72%
793
September16th to endNight
92%
656
46%
1815
45%
656
94%
656
78%
756
October1st to 15thNight
78%
660
37%
1853
36%
660
82%
660
58%
899
October16th to endNight
76%
704
41%
2123
40%
704
81%
704
56%
980
November1st to 15thNight
74%
700
36%
2275
35%
700
82%
700
58%
979
November16th to endNight
69%
720
38%
2340
35%
720
78%
720
53%
1060
December1st to 15thNight
61%
720
34%
2340
28%
720
71%
720
39%
1192
December16th to endNight
54%
768
32%
2616
27%
768
65%
768
35%
1348

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%
45879
Night
4212212235%70%
45536
TransparencyDay
17%36%16%28%27%
45571
Night
17%36%16%27%28%
45345
SeeingDay
6%9%28%39%13%3
5293
Night
5%212%35%35%8%
15278

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%213323245%63%
1474
16th to endDay
10%5%23212345%57%
1821
February1st to 15thDay
7%222322246%61%
1751
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%423313236%63%
2044
16th to endDay
4212212236%70%
1980
May1st to 15thDay
3312212346%70%
2048
16th to endDay
2212211246%71%
2221
June1st to 15thDay
3311112335%72%
2255
16th to endDay
111111385%
2310
July1st to 15thDay
11211223477%
2310
16th to endDay
21222245%75%
2245
August1st to 15thDay
111122483%
1980
16th to endDay
11222384%
2100
September1st to 15thDay
111112384%
1966
16th to endDay
111121284%
1815
October1st to 15thDay
421121234471%
1776
16th to endDay
22231233472%
1749
November1st to 15thDay
2312222235%71%
1584
16th to endDay
4313313347%63%
1620
December1st to 15thDay
6%31232335%9%57%
1620
16th to endDay
9%423414435%56%
1605
January1st to 15thNight
6%313312346%61%
2461
16th to endNight
9%413212236%60%
2400
February1st to 15thNight
6%423312345%63%
2101
16th to endNight
10%423323345%55%
1895
March1st to 15thNight
431221335%8%62%
2160
16th to endNight
5%22314448%63%
1994
April1st to 15thNight
5%312313235%65%
1719
16th to endNight
3311111246%72%
1650
May1st to 15thNight
3312212346%68%
1569
16th to endNight
1212212236%73%
1540
June1st to 15thNight
111111338%73%
1372
16th to endNight
1111388%
1320
July1st to 15thNight
12212135%78%
1320
16th to endNight
221212235%75%
1609
August1st to 15thNight
1111212482%
1650
16th to endNight
111112384%
1750
September1st to 15thNight
2111121481%
1664
16th to endNight
11112385%
1815
October1st to 15thNight
311211333373%
1853
16th to endNight
32211222474%
2123
November1st to 15thNight
32221222474%
2275
16th to endNight
4212213346%68%
2340
December1st to 15thNight
7%314322336%60%
2340
16th to endNight
10%313213336%59%
2616

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%26%13%26%26%
1474
16th to endDay
28%37%15%17%26%
1821
February1st to 15thDay
23%36%14%26%25%
1751
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
23%411%23%24%13%
2044
16th to endDay
17%39%21%30%17%
1980
May1st to 15thDay
17%49%20%26%22%
2048
16th to endDay
16%39%26%33%11%
2224
June1st to 15thDay
16%38%16%33%21%
2255
16th to endDay
7%148%38%39%
2310
July1st to 15thDay
12%249%28%41%
2161
16th to endDay
12%36%19%30%27%
2097
August1st to 15thDay
8%1312%35%39%
1966
16th to endDay
6%1311%39%37%
2100
September1st to 15thDay
7%25%11%28%45%
1966
16th to endDay
8%1211%33%41%
1815
October1st to 15thDay
17%26%17%27%28%
1776
16th to endDay
16%3410%24%39%
1749
November1st to 15thDay
18%25%14%28%30%
1584
16th to endDay
21%35%14%22%32%
1620
December1st to 15thDay
24%49%15%24%21%
1620
16th to endDay
30%47%17%22%17%
1605
January1st to 15thNight
24%26%15%25%25%
2461
16th to endNight
26%37%13%18%30%
2400
February1st to 15thNight
22%36%15%24%27%
2112
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
22%211%27%21%14%
1719
16th to endNight
14%49%22%30%18%
1650
May1st to 15thNight
18%5%8%19%29%18%
1570
16th to endNight
14%311%27%31%13%
1541
June1st to 15thNight
11%411%15%33%23%
1372
16th to endNight
6%1310%35%43%
1320
July1st to 15thNight
10%1413%25%44%
1240
16th to endNight
12%25%20%28%30%
1495
August1st to 15thNight
8%1210%36%40%
1640
16th to endNight
7%210%38%40%
1750
September1st to 15thNight
10%238%28%46%
1664
16th to endNight
7%1111%35%42%
1815
October1st to 15thNight
16%3416%30%29%
1853
16th to endNight
16%3411%23%40%
2123
November1st to 15thNight
15%15%14%26%35%
2275
16th to endNight
18%26%16%23%32%
2340
December1st to 15thNight
26%37%15%22%24%
2340
16th to endNight
27%37%16%25%19%
2616

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
16%12%50%15%3
102
16th to endDay
16%15%35%25%41
271
February1st to 15thDay
8%14%35%31%8%
266
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
11%15%39%23%6%2
234
16th to endDay
421%38%29%41
210
May1st to 15thDay
7%11%34%35%8%2
228
16th to endDay
5%13%33%32%12%2
266
June1st to 15thDay
5%6%25%50%9%3
255
16th to endDay
121%45%21%9%
255
July1st to 15thDay
115%53%23%6%
245
16th to endDay
28%51%26%9%
271
August1st to 15thDay
212%58%17%7%
255
16th to endDay
12%57%19%9%
268
September1st to 15thDay
1220%55%14%5%
255
16th to endDay
2327%48%15%3
255
October1st to 15thDay
39%37%37%12%
255
16th to endDay
5%6%28%42%15%
261
November1st to 15thDay
35%18%35%26%10%
90
16th to endDay
411%37%36%8%1
90
December1st to 15thDay
5%6%27%45%14%
90
16th to endDay
12%12%37%32%6%
75
January1st to 15thNight
7%423%44%16%4
720
16th to endNight
12%420%41%17%3
768
February1st to 15thNight
7%119%43%23%5%
704
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%26%3
687
16th to endNight
5%317%36%31%6%
660
May1st to 15thNight
6%214%37%35%3
580
16th to endNight
2312%40%36%4
515
June1st to 15thNight
18%39%46%4
382
16th to endNight
32%61%5%
330
July1st to 15thNight
16%71%10%
310
16th to endNight
1111%66%17%
557
August1st to 15thNight
1117%63%15%
657
16th to endNight
114%61%21%
700
September1st to 15thNight
3120%54%20%
660
16th to endNight
430%47%16%
656
October1st to 15thNight
5%19%39%38%5%
660
16th to endNight
5%113%34%34%10%
704
November1st to 15thNight
5%114%41%29%7%
700
16th to endNight
6%118%39%26%7%
720
December1st to 15thNight
9%5%17%41%21%4
720
16th to endNight
13%7%19%40%15%2
768
Page generated at 2017-04-08 02:35:20. Version ac04

Copyright 2017 A. Danko


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