Saddleback Butte
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saddleback Butte clear sky chart from 2005-11-05 to 2017-09-17.

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%
15782
38%
46791
31%
15739
79%
15739
65%
20310

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
66%
716
30%
2506
30%
716
73%
716
47%
1145
January16th to endNight
63%
768
38%
2337
31%
768
73%
768
51%
1114
February1st to 15thNight
68%
697
35%
2107
32%
697
76%
697
53%
1008
February16th to endNight
61%
632
33%
1895
31%
632
69%
632
49%
937
March1st to 15thNight
65%
720
32%
2160
30%
720
74%
720
57%
994
March16th to endNight
63%
768
36%
2014
24%
768
72%
768
63%
972
April1st to 15thNight
55%
719
35%
1799
15%
719
66%
719
61%
906
April16th to endNight
60%
720
38%
1800
17%
720
70%
720
74%
827
May1st to 15thNight
65%
590
38%
1669
23%
589
71%
589
78%
668
May16th to endNight
58%
561
37%
1685
23%
561
67%
561
75%
648
June1st to 15thNight
72%
466
37%
1546
30%
466
80%
466
84%
516
June16th to endNight
85%
360
43%
1440
48%
360
91%
360
87%
399
July1st to 15thNight
92%
340
37%
1360
44%
340
94%
340
71%
434
July16th to endNight
91%
588
37%
1612
31%
550
91%
550
69%
689
August1st to 15thNight
92%
717
40%
1790
25%
713
93%
713
87%
767
August16th to endNight
92%
764
47%
1910
31%
764
93%
764
85%
839
September1st to 15thNight
91%
720
44%
1838
33%
720
93%
720
83%
798
September16th to endNight
85%
664
48%
1837
41%
664
92%
664
85%
728
October1st to 15thNight
76%
660
42%
1818
35%
660
84%
660
70%
808
October16th to endNight
78%
704
45%
2157
43%
704
86%
704
70%
869
November1st to 15thNight
77%
700
39%
2275
40%
700
84%
700
65%
916
November16th to endNight
78%
720
41%
2340
41%
720
84%
720
61%
975
December1st to 15thNight
67%
720
35%
2340
31%
720
75%
720
48%
1104
December16th to endNight
58%
768
32%
2556
28%
768
67%
768
43%
1249

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
111212236%75%
47960
Night
111112235%76%
46986
TransparencyDay
11%25%16%27%35%
47649
Night
11%26%18%30%30%
46797
SeeingDay
37%24%33%22%8%
5876
Night
2219%40%30%5%
15795

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
2213323346%65%
1432
16th to endDay
3313323346%61%
1878
February1st to 15thDay
1112312347%67%
1751
16th to endDay
3213422347%62%
1579
March1st to 15thDay
11121346%10%66%
1800
16th to endDay
1111135%5%8%68%
2205
April1st to 15thDay
212222346%72%
2149
16th to endDay
111237%79%
2160
May1st to 15thDay
111236%81%
2280
16th to endDay
1111212382%
2429
June1st to 15thDay
1225%84%
2409
16th to endDay
1111290%
2520
July1st to 15thDay
1221223478%
2520
16th to endDay
21112235%76%
2438
August1st to 15thDay
111112485%
2160
16th to endDay
111213482%
2292
September1st to 15thDay
112225%81%
2121
16th to endDay
1221385%
1828
October1st to 15thDay
11112336%76%
1810
16th to endDay
111111235%80%
1713
November1st to 15thDay
111213225%76%
1584
16th to endDay
211312337%70%
1620
December1st to 15thDay
221222346%9%62%
1620
16th to endDay
42134135%5%6%60%
1662
January1st to 15thNight
2214323348%64%
2506
16th to endNight
3212322346%66%
2337
February1st to 15thNight
2212223337%68%
2101
16th to endNight
3212315%46%6%62%
1895
March1st to 15thNight
111221335%7%68%
2160
16th to endNight
112223348%70%
2014
April1st to 15thNight
111121235%6%72%
1799
16th to endNight
1111123481%
1800
May1st to 15thNight
11246%81%
1669
16th to endNight
111125%84%
1684
June1st to 15thNight
1225%86%
1546
16th to endNight
11292%
1440
July1st to 15thNight
11111112482%
1440
16th to endNight
11112235%78%
1724
August1st to 15thNight
112289%
1800
16th to endNight
11113286%
1910
September1st to 15thNight
1112386%
1838
16th to endNight
1112288%
1837
October1st to 15thNight
11111243478%
1818
16th to endNight
1111212481%
2157
November1st to 15thNight
111112235%76%
2275
16th to endNight
212212336%73%
2340
December1st to 15thNight
2212223446%65%
2340
16th to endNight
4313313437%63%
2556

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
20%39%22%28%16%
1432
16th to endDay
24%38%21%23%18%
1878
February1st to 15thDay
17%36%24%28%20%
1751
16th to endDay
21%47%24%31%11%
1579
March1st to 15thDay
12%39%25%28%20%
1800
16th to endDay
13%311%27%27%17%
2205
April1st to 15thDay
14%26%24%33%18%
2149
16th to endDay
7%28%23%33%24%
2160
May1st to 15thDay
7%16%19%34%31%
2280
16th to endDay
9%25%17%40%26%
2432
June1st to 15thDay
5%1312%26%50%
2409
16th to endDay
41416%71%
2520
July1st to 15thDay
9%227%17%61%
2371
16th to endDay
11%1313%24%45%
2287
August1st to 15thDay
6%17%20%63%
2146
16th to endDay
8%126%24%56%
2292
September1st to 15thDay
7%236%25%53%
2121
16th to endDay
5%216%32%51%
1828
October1st to 15thDay
10%3315%32%34%
1810
16th to endDay
8%2413%31%38%
1713
November1st to 15thDay
12%26%17%38%23%
1584
16th to endDay
14%47%20%29%23%
1620
December1st to 15thDay
17%410%23%28%15%
1620
16th to endDay
23%412%25%21%12%
1662
January1st to 15thNight
19%46%20%30%17%
2506
16th to endNight
18%38%21%25%21%
2337
February1st to 15thNight
17%48%20%26%22%
2112
16th to endNight
19%5%9%22%29%13%
1895
March1st to 15thNight
14%310%23%26%20%
2160
16th to endNight
12%311%27%29%14%
2014
April1st to 15thNight
13%38%30%27%16%
1799
16th to endNight
8%28%28%35%18%
1800
May1st to 15thNight
5%27%24%37%23%
1670
16th to endNight
5%27%24%41%19%
1685
June1st to 15thNight
316%16%32%40%
1546
16th to endNight
226%22%64%
1440
July1st to 15thNight
7%227%18%62%
1360
16th to endNight
10%2411%27%42%
1612
August1st to 15thNight
3118%26%58%
1790
16th to endNight
5%118%30%53%
1910
September1st to 15thNight
5%137%31%50%
1838
16th to endNight
4118%38%46%
1837
October1st to 15thNight
10%2413%35%32%
1818
16th to endNight
8%2411%31%40%
2157
November1st to 15thNight
11%25%18%34%28%
2275
16th to endNight
12%27%21%27%28%
2340
December1st to 15thNight
19%49%19%29%17%
2340
16th to endNight
21%5%12%23%23%14%
2556

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
11%10%23%31%21%1
60
16th to endDay
8%12%24%25%19%10%
278
February1st to 15thDay
412%24%27%19%11%
266
16th to endDay
8%13%26%26%17%6%
238
March1st to 15thDay
413%24%30%21%6%
270
16th to endDay
315%29%27%20%2
288
April1st to 15thDay
417%33%21%16%5%
269
16th to endDay
316%38%25%11%5%
270
May1st to 15thDay
211%30%32%16%6%
288
16th to endDay
310%32%27%18%7%
330
June1st to 15thDay
16%29%35%19%6%
315
16th to endDay
326%37%22%9%
315
July1st to 15thDay
118%44%24%10%
305
16th to endDay
213%42%26%13%
327
August1st to 15thDay
217%47%21%11%
315
16th to endDay
11%45%28%13%
332
September1st to 15thDay
118%35%34%8%
315
16th to endDay
1417%35%30%11%
260
October1st to 15thDay
28%25%32%25%5%
255
16th to endDay
2324%27%32%10%
225
November1st to 15thDay
1314%22%36%22%
90
16th to endDay
310%21%35%30%
90
December1st to 15thDay
15%20%33%31%8%
90
16th to endDay
9%12%22%25%27%2
85
January1st to 15thNight
3221%40%25%6%
720
16th to endNight
4223%40%26%3
768
February1st to 15thNight
2320%41%27%4
704
16th to endNight
4426%40%20%4
632
March1st to 15thNight
1425%41%23%4
720
16th to endNight
1427%40%23%2
768
April1st to 15thNight
26%32%35%19%3
719
16th to endNight
15%31%37%20%4
720
May1st to 15thNight
328%45%19%2
590
16th to endNight
5%33%37%21%
563
June1st to 15thNight
224%52%19%1
466
16th to endNight
12%56%28%
360
July1st to 15thNight
1343%49%2
340
16th to endNight
1342%47%3
588
August1st to 15thNight
15%44%42%7%
717
16th to endNight
435%47%11%
764
September1st to 15thNight
5%36%47%9%
720
16th to endNight
11%33%44%9%
664
October1st to 15thNight
1117%41%31%6%
660
16th to endNight
2115%34%35%10%
704
November1st to 15thNight
1116%37%35%8%
700
16th to endNight
2213%39%35%7%
720
December1st to 15thNight
4221%39%28%4
720
16th to endNight
6%425%36%23%3
768
Page generated at 2017-09-18 05:38:22. Version ac04

Copyright 2017 A. Danko


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