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 2018-10-08.

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%
17183
38%
50945
31%
17140
80%
17140
65%
22038

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%
776
30%
2716
30%
776
73%
776
46%
1259
January16th to endNight
65%
832
38%
2532
32%
832
74%
832
52%
1196
February1st to 15thNight
68%
757
36%
2287
31%
757
77%
757
54%
1077
February16th to endNight
61%
684
34%
2051
33%
684
69%
684
50%
1004
March1st to 15thNight
64%
780
31%
2340
29%
780
73%
780
55%
1093
March16th to endNight
62%
832
35%
2182
23%
832
71%
832
62%
1066
April1st to 15thNight
54%
779
36%
1949
16%
779
66%
779
61%
986
April16th to endNight
60%
772
37%
1930
16%
772
69%
772
74%
886
May1st to 15thNight
64%
639
38%
1808
23%
638
71%
638
76%
734
May16th to endNight
58%
609
37%
1829
22%
609
67%
609
75%
704
June1st to 15thNight
73%
505
39%
1675
32%
505
81%
505
85%
555
June16th to endNight
86%
390
42%
1560
47%
390
92%
390
88%
429
July1st to 15thNight
92%
370
39%
1480
45%
370
94%
370
71%
472
July16th to endNight
91%
637
36%
1757
30%
599
91%
599
70%
748
August1st to 15thNight
92%
765
41%
1910
26%
761
93%
761
88%
818
August16th to endNight
92%
828
45%
2070
30%
828
93%
828
85%
908
September1st to 15thNight
91%
780
46%
1991
36%
780
93%
780
84%
858
September16th to endNight
86%
776
48%
2145
41%
776
92%
776
87%
840
October1st to 15thNight
75%
752
43%
2071
34%
752
84%
752
72%
908
October16th to endNight
79%
768
47%
2353
46%
768
87%
768
72%
934
November1st to 15thNight
77%
760
38%
2470
38%
760
84%
760
65%
998
November16th to endNight
78%
780
42%
2535
42%
780
84%
780
61%
1057
December1st to 15thNight
68%
780
35%
2535
31%
780
76%
780
50%
1174
December16th to endNight
59%
832
34%
2769
29%
832
69%
832
44%
1334

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
111212235%76%
52164
Night
111112235%76%
51140
TransparencyDay
11%25%16%28%35%
51853
Night
11%26%17%30%30%
50951
SeeingDay
27%22%32%23%10%
7289
Night
2219%40%30%5%
17196

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
2213324346%64%
1552
16th to endDay
3313323346%62%
2035
February1st to 15thDay
1112322347%68%
1901
16th to endDay
3213412347%65%
1709
March1st to 15thDay
21221346%10%65%
1950
16th to endDay
11121135%5%8%68%
2389
April1st to 15thDay
212222346%71%
2329
16th to endDay
111237%79%
2305
May1st to 15thDay
1111226%81%
2471
16th to endDay
112212481%
2637
June1st to 15thDay
1225%85%
2610
16th to endDay
111291%
2730
July1st to 15thDay
1221223477%
2730
16th to endDay
21112246%75%
2643
August1st to 15thDay
111112486%
2293
16th to endDay
111223482%
2484
September1st to 15thDay
11222482%
2298
16th to endDay
121486%
2145
October1st to 15thDay
11111236%77%
2055
16th to endDay
111111235%80%
1869
November1st to 15thDay
111213235%75%
1719
16th to endDay
211212338%70%
1755
December1st to 15thDay
221221346%9%63%
1755
16th to endDay
421341345%6%61%
1800
January1st to 15thNight
2214323348%62%
2716
16th to endNight
3212322346%66%
2532
February1st to 15thNight
2212223336%69%
2281
16th to endNight
321231445%6%63%
2051
March1st to 15thNight
211221345%8%66%
2340
16th to endNight
112223348%69%
2182
April1st to 15thNight
1112212346%71%
1949
16th to endNight
11111235%80%
1930
May1st to 15thNight
11246%81%
1808
16th to endNight
11125%84%
1828
June1st to 15thNight
122487%
1675
16th to endNight
11293%
1560
July1st to 15thNight
111112482%
1560
16th to endNight
111112235%77%
1869
August1st to 15thNight
112289%
1920
16th to endNight
11113285%
2070
September1st to 15thNight
112387%
1991
16th to endNight
112289%
2145
October1st to 15thNight
1111233479%
2071
16th to endNight
111113482%
2353
November1st to 15thNight
111112345%75%
2470
16th to endNight
22212336%73%
2535
December1st to 15thNight
2212223446%66%
2535
16th to endNight
4213313437%63%
2769

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%310%23%26%15%
1552
16th to endDay
23%38%22%24%17%
2035
February1st to 15thDay
16%36%22%29%21%
1901
16th to endDay
19%46%23%32%13%
1709
March1st to 15thDay
14%38%26%28%19%
1950
16th to endDay
13%311%26%28%16%
2389
April1st to 15thDay
14%27%23%32%19%
2329
16th to endDay
7%28%23%34%24%
2305
May1st to 15thDay
7%25%18%35%30%
2471
16th to endDay
9%2417%40%25%
2640
June1st to 15thDay
41311%26%51%
2610
16th to endDay
41316%72%
2730
July1st to 15thDay
10%227%17%59%
2581
16th to endDay
11%1415%24%42%
2492
August1st to 15thDay
5%17%20%63%
2279
16th to endDay
8%125%26%55%
2484
September1st to 15thDay
7%236%24%55%
2298
16th to endDay
5%115%33%52%
2145
October1st to 15thDay
9%3315%31%37%
2055
16th to endDay
8%2413%30%40%
1869
November1st to 15thDay
12%26%19%37%21%
1719
16th to endDay
13%47%20%30%23%
1755
December1st to 15thDay
16%410%22%27%18%
1755
16th to endDay
22%412%23%23%13%
1800
January1st to 15thNight
20%47%22%29%16%
2716
16th to endNight
18%38%21%26%21%
2532
February1st to 15thNight
16%38%19%28%23%
2292
16th to endNight
18%49%21%29%15%
2051
March1st to 15thNight
15%411%23%26%19%
2340
16th to endNight
13%311%27%30%13%
2182
April1st to 15thNight
13%48%29%27%16%
1949
16th to endNight
8%18%27%36%17%
1930
May1st to 15thNight
5%27%23%39%22%
1809
16th to endNight
5%26%24%43%17%
1829
June1st to 15thNight
215%15%32%42%
1675
16th to endNight
226%22%65%
1560
July1st to 15thNight
6%228%18%60%
1480
16th to endNight
10%2414%27%41%
1757
August1st to 15thNight
3118%25%59%
1910
16th to endNight
5%117%31%52%
2070
September1st to 15thNight
5%136%31%51%
1991
16th to endNight
3117%39%47%
2145
October1st to 15thNight
9%2414%35%34%
2071
16th to endNight
8%2412%29%43%
2353
November1st to 15thNight
11%25%19%34%26%
2470
16th to endNight
13%26%20%28%27%
2535
December1st to 15thNight
18%48%18%29%20%
2535
16th to endNight
21%411%21%25%15%
2769

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
8%7%22%24%33%3
90
16th to endDay
7%12%21%24%22%12%
339
February1st to 15thDay
310%25%25%19%16%
326
16th to endDay
7%14%25%26%19%6%
290
March1st to 15thDay
5%14%23%31%19%5%
330
16th to endDay
314%29%28%21%2
352
April1st to 15thDay
317%32%24%17%4
329
16th to endDay
216%36%25%13%5%
318
May1st to 15thDay
211%30%31%17%6%
348
16th to endDay
210%31%28%18%7%
394
June1st to 15thDay
15%27%34%20%11%
375
16th to endDay
224%36%24%12%
375
July1st to 15thDay
116%41%25%15%
365
16th to endDay
212%40%27%17%
391
August1st to 15thDay
115%46%21%14%
359
16th to endDay
12%44%26%14%
396
September1st to 15thDay
118%34%36%7%
375
16th to endDay
316%38%29%10%
375
October1st to 15thDay
28%23%34%25%5%
345
16th to endDay
1421%26%31%14%
285
November1st to 15thDay
3217%28%31%14%
135
16th to endDay
29%18%28%31%8%
135
December1st to 15thDay
5%22%28%32%10%
135
16th to endDay
6%9%21%22%30%9%
127
January1st to 15thNight
3121%40%26%6%
780
16th to endNight
4222%40%27%3
832
February1st to 15thNight
2320%40%28%4
764
16th to endNight
4426%39%20%3
684
March1st to 15thNight
2425%41%22%3
780
16th to endNight
1428%39%23%2
832
April1st to 15thNight
26%32%35%19%2
779
16th to endNight
15%31%36%20%4
772
May1st to 15thNight
428%45%19%2
639
16th to endNight
5%34%38%20%
611
June1st to 15thNight
223%52%20%1
505
16th to endNight
12%56%29%
390
July1st to 15thNight
1342%50%2
370
16th to endNight
343%47%3
637
August1st to 15thNight
15%44%41%7%
765
16th to endNight
436%47%11%
828
September1st to 15thNight
5%37%46%9%
780
16th to endNight
11%36%42%8%
776
October1st to 15thNight
1118%41%30%5%
752
16th to endNight
1114%34%35%11%
768
November1st to 15thNight
116%39%34%7%
760
16th to endNight
2113%37%36%7%
780
December1st to 15thNight
3221%38%29%4
780
16th to endNight
6%324%36%24%4
832
Page generated at 2018-10-09 07:39:17. Version ac04

Copyright 2018 A. Danko


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