Saguaro Cliffs Observatory Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saguaro Cliffs Observatory Site clear sky chart from 2005-11-05 to 2017-12-01.

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
77%
15891
37%
47802
33%
15854
82%
15854
56%
22365

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
73%
717
33%
2327
33%
716
77%
716
52%
1066
January16th to endNight
69%
768
35%
2496
34%
768
75%
768
43%
1267
February1st to 15thNight
75%
700
37%
2196
37%
700
81%
700
54%
1011
February16th to endNight
68%
632
39%
1840
36%
632
75%
632
52%
920
March1st to 15thNight
69%
720
41%
1980
33%
720
76%
720
61%
952
March16th to endNight
76%
768
40%
2112
29%
768
83%
768
63%
989
April1st to 15thNight
70%
689
36%
1948
26%
689
77%
689
60%
912
April16th to endNight
74%
540
46%
1778
42%
540
83%
540
73%
649
May1st to 15thNight
75%
539
41%
1619
32%
539
83%
539
74%
636
May16th to endNight
78%
561
43%
1684
35%
561
83%
561
76%
651
June1st to 15thNight
84%
540
35%
1620
31%
540
85%
540
71%
668
June16th to endNight
87%
540
33%
1620
28%
540
88%
540
66%
693
July1st to 15thNight
82%
510
22%
1530
19%
510
82%
510
43%
810
July16th to endNight
83%
564
20%
1593
17%
531
83%
531
33%
953
August1st to 15thNight
87%
539
26%
1611
23%
536
87%
536
46%
836
August16th to endNight
86%
608
32%
1880
32%
608
86%
608
42%
1002
September1st to 15thNight
80%
720
30%
1980
26%
720
81%
720
44%
1133
September16th to endNight
82%
716
45%
1980
35%
716
87%
716
69%
885
October1st to 15thNight
81%
720
40%
2085
33%
720
86%
720
67%
917
October16th to endNight
88%
768
46%
2304
42%
768
90%
768
71%
964
November1st to 15thNight
80%
760
43%
2280
39%
760
84%
760
67%
971
November16th to endNight
76%
780
41%
2490
39%
780
81%
780
54%
1132
December1st to 15thNight
74%
724
39%
2353
40%
724
78%
724
51%
1071
December16th to endNight
67%
768
35%
2496
36%
768
72%
768
42%
1277

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
3212323346%67%
48614
Night
3112213346%69%
47998
TransparencyDay
18%35%11%24%37%
48309
Night
16%35%12%25%35%
47804
SeeingDay
5%7%20%34%23%8%
5665
Night
4111%41%35%5%
15901

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
4113323336%66%
1611
16th to endDay
6%313323346%61%
1728
February1st to 15thDay
6%212212236%68%
1664
16th to endDay
7%222213336%64%
1633
March1st to 15thDay
412313246%68%
1980
16th to endDay
31121223474%
2112
April1st to 15thDay
311212246%73%
1998
16th to endDay
2111112382%
2179
May1st to 15thDay
1111223480%
2331
16th to endDay
1111122384%
2429
June1st to 15thDay
21111125%79%
2340
16th to endDay
1111222246%73%
2340
July1st to 15thDay
3314436%8%8%9%46%
2340
16th to endDay
6%427%7%36%7%8%11%31%
2467
August1st to 15thDay
5%325%5%35%6%7%8%45%
2340
16th to endDay
32145%45%6%6%6%51%
2315
September1st to 15thDay
5%3145%25%5%6%7%53%
1980
16th to endDay
31211223474%
1980
October1st to 15thDay
21123235%76%
1873
16th to endDay
111111135%79%
1920
November1st to 15thDay
111112246%76%
1909
16th to endDay
322212335%72%
1797
December1st to 15thDay
7%212213247%64%
1620
16th to endDay
7%21231235%6%63%
1728
January1st to 15thNight
5%213213335%67%
2327
16th to endNight
6%313324445%60%
2496
February1st to 15thNight
5%112213345%68%
2185
16th to endNight
6%211224345%64%
1840
March1st to 15thNight
5%112212335%70%
1980
16th to endNight
21222223474%
2112
April1st to 15thNight
3112223345%71%
1948
16th to endNight
21111386%
1778
May1st to 15thNight
112236%79%
1619
16th to endNight
11212285%
1684
June1st to 15thNight
2111212381%
1620
16th to endNight
111112235%77%
1620
July1st to 15thNight
2114325%6%7%10%52%
1620
16th to endNight
3214445%8%10%15%40%
1701
August1st to 15thNight
21123246%7%8%57%
1620
16th to endNight
32134345%7%10%53%
1880
September1st to 15thNight
42144245%5%8%55%
1980
16th to endNight
21121123477%
1980
October1st to 15thNight
1111223478%
2085
16th to endNight
11111222481%
2304
November1st to 15thNight
111212336%75%
2280
16th to endNight
5%212212335%69%
2490
December1st to 15thNight
6%212212345%67%
2353
16th to endNight
8%213422345%60%
2496

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
19%3413%26%31%
1612
16th to endDay
23%3414%25%28%
1728
February1st to 15thDay
19%1312%27%34%
1664
16th to endDay
22%2313%30%27%
1633
March1st to 15thDay
17%236%31%40%
1980
16th to endDay
13%228%30%42%
2112
April1st to 15thDay
13%125%35%41%
1998
16th to endDay
8%115%23%57%
2179
May1st to 15thDay
9%127%20%58%
2331
16th to endDay
7%116%22%59%
2432
June1st to 15thDay
9%12319%64%
2340
16th to endDay
12%335%15%58%
2340
July1st to 15thDay
28%8%12%15%14%19%
2201
16th to endDay
40%10%17%18%9%2
2312
August1st to 15thDay
32%8%12%14%17%14%
2325
16th to endDay
28%6%11%18%18%16%
2315
September1st to 15thDay
28%6%8%17%17%21%
1980
16th to endDay
14%148%32%38%
1980
October1st to 15thDay
11%2410%26%44%
1873
16th to endDay
9%139%25%50%
1920
November1st to 15thDay
10%2212%34%38%
1909
16th to endDay
16%229%29%40%
1797
December1st to 15thDay
20%2415%31%24%
1620
16th to endDay
21%26%19%32%17%
1728
January1st to 15thNight
19%25%13%27%31%
2327
16th to endNight
24%4413%30%23%
2496
February1st to 15thNight
17%3415%25%33%
2196
16th to endNight
20%2413%32%27%
1840
March1st to 15thNight
15%2310%26%41%
1980
16th to endNight
14%2310%31%38%
2112
April1st to 15thNight
15%137%34%36%
1948
16th to endNight
7%116%25%57%
1778
May1st to 15thNight
7%137%25%53%
1620
16th to endNight
7%116%24%58%
1685
June1st to 15thNight
9%21320%63%
1620
16th to endNight
12%13418%59%
1620
July1st to 15thNight
21%8%15%18%15%20%
1530
16th to endNight
26%13%22%23%10%3
1593
August1st to 15thNight
19%8%16%20%19%16%
1611
16th to endNight
23%7%13%20%18%17%
1880
September1st to 15thNight
25%6%8%21%19%17%
1980
16th to endNight
11%2410%34%36%
1980
October1st to 15thNight
11%2313%25%43%
2085
16th to endNight
10%1310%24%49%
2304
November1st to 15thNight
11%1413%32%36%
2280
16th to endNight
18%2310%25%40%
2490
December1st to 15thNight
19%2417%30%26%
2353
16th to endNight
25%35%17%29%19%
2496

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
10%420%46%17%1
90
16th to endDay
7%212%41%26%10%
96
February1st to 15thDay
7%8%20%36%23%3
179
16th to endDay
10%12%38%24%11%2
238
March1st to 15thDay
5%15%29%27%14%8%
270
16th to endDay
315%34%24%14%7%
288
April1st to 15thDay
417%31%26%15%4
269
16th to endDay
222%31%27%12%2
270
May1st to 15thDay
216%33%29%13%4
288
16th to endDay
27%30%39%16%3
330
June1st to 15thDay
4328%40%17%6%
315
16th to endDay
2112%48%24%10%
315
July1st to 15thDay
5%8%41%32%11%
305
16th to endDay
7%6%33%29%22%
327
August1st to 15thDay
6%15%34%35%16%
315
16th to endDay
46%33%37%18%
332
September1st to 15thDay
7%215%35%29%9%
315
16th to endDay
6%422%32%26%6%
315
October1st to 15thDay
25%20%37%22%12%
208
16th to endDay
116%33%45%12%
144
November1st to 15thDay
25%18%37%31%5%
135
16th to endDay
6%220%34%28%7%
135
December1st to 15thDay
3211%30%51%2
90
16th to endDay
15%423%38%16%1
96
January1st to 15thNight
6%13%50%24%3
720
16th to endNight
7%314%44%26%3
768
February1st to 15thNight
4211%48%27%5%
704
16th to endNight
7%217%50%19%1
632
March1st to 15thNight
4319%42%26%3
720
16th to endNight
2314%47%28%4
768
April1st to 15thNight
3316%52%20%2
689
16th to endNight
1319%50%21%2
540
May1st to 15thNight
1318%46%28%1
540
16th to endNight
1215%48%31%
563
June1st to 15thNight
119%49%36%1
540
16th to endNight
15%38%52%1
540
July1st to 15thNight
15%23%61%6%
510
16th to endNight
3116%63%14%
564
August1st to 15thNight
3117%63%13%
539
16th to endNight
3123%59%12%
608
September1st to 15thNight
5%6%27%48%12%
720
16th to endNight
210%37%41%7%
716
October1st to 15thNight
212%42%37%5%
720
16th to endNight
26%44%37%8%
768
November1st to 15thNight
2111%43%36%5%
760
16th to endNight
6%112%43%32%4
780
December1st to 15thNight
7%211%44%29%4
724
16th to endNight
8%312%49%20%4
768
Page generated at 2017-12-02 07:14:19. Version ac04

Copyright 2017 A. Danko


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