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 2017-04-07.

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
72%
15257
38%
45295
31%
15214
79%
15214
64%
19734

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
54%
687
36%
1719
16%
687
66%
687
60%
870
April16th to endNight
62%
660
37%
1650
17%
660
70%
660
74%
759
May1st to 15thNight
65%
541
39%
1530
24%
540
71%
540
76%
619
May16th to endNight
57%
513
35%
1541
21%
513
66%
513
75%
589
June1st to 15thNight
72%
427
39%
1417
31%
427
80%
427
83%
477
June16th to endNight
85%
330
40%
1320
45%
330
91%
330
86%
369
July1st to 15thNight
92%
310
39%
1240
46%
310
94%
310
71%
397
July16th to endNight
90%
543
35%
1483
29%
505
91%
505
68%
640
August1st to 15thNight
93%
657
42%
1640
27%
653
94%
653
88%
701
August16th to endNight
92%
700
44%
1750
29%
700
93%
700
84%
771
September1st to 15thNight
91%
660
46%
1685
35%
660
93%
660
83%
731
September16th to endNight
85%
656
48%
1815
41%
656
91%
656
85%
720
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%
45914
Night
111212235%75%
45490
TransparencyDay
11%25%16%28%34%
45603
Night
11%36%18%30%29%
45301
SeeingDay
38%25%33%22%7%
5232
Night
2219%39%30%5%
15270

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
212222345%72%
2044
16th to endDay
1111236%80%
1980
May1st to 15thDay
1111236%81%
2089
16th to endDay
111212482%
2221
June1st to 15thDay
1235%84%
2208
16th to endDay
1111289%
2310
July1st to 15thDay
12212235%78%
2310
16th to endDay
21112235%76%
2259
August1st to 15thDay
11112486%
1980
16th to endDay
111213483%
2100
September1st to 15thDay
11222482%
1944
16th to endDay
1221485%
1815
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
121121235%6%72%
1719
16th to endNight
11111123482%
1650
May1st to 15thNight
11246%81%
1530
16th to endNight
1125%84%
1540
June1st to 15thNight
1225%86%
1417
16th to endNight
11292%
1320
July1st to 15thNight
1111113482%
1320
16th to endNight
1111223477%
1595
August1st to 15thNight
112289%
1650
16th to endNight
11113286%
1750
September1st to 15thNight
1112386%
1685
16th to endNight
1112288%
1815
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%25%31%18%
2044
16th to endDay
7%27%24%33%24%
1980
May1st to 15thDay
7%26%19%33%32%
2089
16th to endDay
9%2418%40%24%
2224
June1st to 15thDay
5%1412%25%50%
2208
16th to endDay
5%12417%69%
2310
July1st to 15thDay
9%217%17%60%
2161
16th to endDay
11%1413%24%45%
2108
August1st to 15thDay
5%18%21%63%
1966
16th to endDay
7%126%25%55%
2100
September1st to 15thDay
7%235%23%56%
1944
16th to endDay
5%216%32%51%
1815
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%48%31%25%17%
1719
16th to endNight
8%27%28%35%18%
1650
May1st to 15thNight
5%27%23%36%23%
1531
16th to endNight
5%27%25%43%16%
1541
June1st to 15thNight
316%15%32%40%
1417
16th to endNight
327%24%61%
1320
July1st to 15thNight
7%228%18%61%
1240
16th to endNight
10%2411%28%41%
1483
August1st to 15thNight
3118%28%57%
1640
16th to endNight
5%119%30%52%
1750
September1st to 15thNight
5%137%29%52%
1685
16th to endNight
4117%38%46%
1815
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
5%18%35%20%14%5%
234
16th to endDay
416%37%26%11%3
210
May1st to 15thDay
313%32%31%15%4
228
16th to endDay
312%35%27%14%6%
266
June1st to 15thDay
16%31%38%18%3
255
16th to endDay
1329%38%19%7%
255
July1st to 15thDay
122%47%22%5%
245
16th to endDay
2115%45%24%10%
271
August1st to 15thDay
118%49%20%9%
255
16th to endDay
113%49%26%9%
268
September1st to 15thDay
118%36%34%8%
255
16th to endDay
1417%35%30%10%
255
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%36%19%2
687
16th to endNight
15%29%39%20%3
660
May1st to 15thNight
428%46%19%1
541
16th to endNight
6%34%36%21%
515
June1st to 15thNight
224%52%19%1
427
16th to endNight
13%56%28%
330
July1st to 15thNight
1343%49%2
310
16th to endNight
1341%48%4
543
August1st to 15thNight
443%43%7%
657
16th to endNight
1435%48%10%
700
September1st to 15thNight
5%36%47%10%
660
16th to endNight
12%33%44%9%
656
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 2017-04-08 02:35:15. Version ac04

Copyright 2017 A. Danko


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