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 2017-04-28.

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%
15151
37%
45600
33%
15114
81%
15114
56%
21325

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%
534
46%
1760
42%
534
83%
534
73%
642
May1st to 15thNight
75%
494
43%
1484
33%
494
83%
494
75%
579
May16th to endNight
78%
513
40%
1540
33%
513
83%
513
74%
601
June1st to 15thNight
84%
495
37%
1485
33%
495
85%
495
70%
615
June16th to endNight
86%
495
31%
1485
26%
495
87%
495
66%
629
July1st to 15thNight
82%
465
23%
1395
19%
465
82%
465
43%
738
July16th to endNight
84%
522
21%
1467
18%
489
84%
489
35%
856
August1st to 15thNight
87%
494
27%
1476
25%
491
87%
491
46%
761
August16th to endNight
86%
557
29%
1722
30%
557
86%
557
41%
933
September1st to 15thNight
80%
660
31%
1815
27%
660
81%
660
44%
1032
September16th to endNight
82%
656
42%
1815
33%
656
86%
656
68%
819
October1st to 15thNight
81%
660
41%
1911
34%
660
86%
660
65%
856
October16th to endNight
88%
704
44%
2112
41%
704
90%
704
70%
891
November1st to 15thNight
81%
700
44%
2100
40%
700
85%
700
70%
873
November16th to endNight
75%
720
39%
2298
37%
720
80%
720
53%
1048
December1st to 15thNight
74%
720
39%
2340
40%
720
78%
720
52%
1058
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
4212323346%66%
46086
Night
3112213346%69%
45796
TransparencyDay
18%35%11%24%36%
45781
Night
16%35%13%25%34%
45602
SeeingDay
5%7%21%34%22%7%
4861
Night
4111%41%35%5%
15161

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
2111112483%
2144
May1st to 15thDay
1111223481%
2136
16th to endDay
111122384%
2221
June1st to 15thDay
21111135%80%
2145
16th to endDay
1111222245%74%
2145
July1st to 15thDay
33145%36%8%8%10%44%
2145
16th to endDay
6%437%7%36%7%8%11%32%
2285
August1st to 15thDay
6%325%5%35%6%7%8%44%
2145
16th to endDay
32145%45%7%6%7%49%
2121
September1st to 15thDay
6%3145%25%46%7%52%
1815
16th to endDay
312112235%72%
1815
October1st to 15thDay
21133235%74%
1717
16th to endDay
11111135%79%
1760
November1st to 15thDay
111111236%78%
1759
16th to endDay
322212335%71%
1659
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%
1760
May1st to 15thNight
111236%80%
1484
16th to endNight
11212285%
1540
June1st to 15thNight
2111212381%
1485
16th to endNight
121112225%77%
1485
July1st to 15thNight
3114325%6%7%10%52%
1485
16th to endNight
3114445%7%10%15%41%
1575
August1st to 15thNight
22133246%7%8%57%
1485
16th to endNight
32134346%7%10%52%
1722
September1st to 15thNight
4213424448%57%
1815
16th to endNight
21221123475%
1815
October1st to 15thNight
2112223477%
1911
16th to endNight
11111222480%
2112
November1st to 15thNight
111212335%77%
2100
16th to endNight
5%212212335%69%
2298
December1st to 15thNight
6%212222345%67%
2340
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%116%24%57%
2144
May1st to 15thDay
9%126%20%59%
2136
16th to endDay
7%116%22%59%
2224
June1st to 15thDay
8%12217%66%
2145
16th to endDay
12%335%15%58%
2145
July1st to 15thDay
29%9%12%14%14%18%
2006
16th to endDay
39%10%16%20%10%2
2130
August1st to 15thDay
33%8%12%14%16%14%
2130
16th to endDay
29%7%12%19%17%13%
2121
September1st to 15thDay
28%6%9%17%16%21%
1815
16th to endDay
15%149%32%36%
1815
October1st to 15thDay
12%35%10%26%42%
1717
16th to endDay
9%139%26%49%
1760
November1st to 15thDay
9%1210%34%40%
1759
16th to endDay
16%2210%29%39%
1659
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%26%57%
1760
May1st to 15thNight
7%147%25%53%
1485
16th to endNight
7%116%24%58%
1541
June1st to 15thNight
9%11318%64%
1485
16th to endNight
12%13418%59%
1485
July1st to 15thNight
21%8%15%18%15%20%
1395
16th to endNight
24%12%22%24%11%3
1467
August1st to 15thNight
19%8%16%20%18%16%
1476
16th to endNight
24%7%14%20%17%15%
1722
September1st to 15thNight
25%6%8%22%19%17%
1815
16th to endNight
11%2410%33%36%
1815
October1st to 15thNight
12%2413%25%41%
1911
16th to endNight
10%2310%24%49%
2112
November1st to 15thNight
10%1412%32%38%
2100
16th to endNight
18%2310%24%40%
2298
December1st to 15thNight
18%2417%30%26%
2340
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%32%27%12%3
259
May1st to 15thDay
217%35%32%8%3
228
16th to endDay
37%30%41%12%4
266
June1st to 15thDay
4430%40%15%4
255
16th to endDay
3113%50%20%9%
255
July1st to 15thDay
6%19%42%31%9%
245
16th to endDay
7%17%37%29%17%
271
August1st to 15thDay
7%15%38%33%13%
255
16th to endDay
416%35%37%15%
268
September1st to 15thDay
9%215%36%27%8%
255
16th to endDay
8%421%30%27%7%
255
October1st to 15thDay
37%21%36%19%12%
157
16th to endDay
22430%50%11%
96
November1st to 15thDay
37%22%35%23%7%
90
16th to endDay
7%327%36%21%3
90
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
1318%51%22%2
534
May1st to 15thNight
319%47%27%1
495
16th to endNight
1214%49%31%
515
June1st to 15thNight
218%49%36%1
495
16th to endNight
15%38%51%1
495
July1st to 15thNight
115%23%60%7%
465
16th to endNight
317%64%12%
522
August1st to 15thNight
3117%63%13%
494
16th to endNight
2122%59%12%
557
September1st to 15thNight
46%26%49%12%
660
16th to endNight
29%37%42%8%
656
October1st to 15thNight
212%42%36%5%
660
16th to endNight
25%45%37%8%
704
November1st to 15thNight
1112%42%35%5%
700
16th to endNight
6%113%43%31%4
720
December1st to 15thNight
7%211%44%29%4
720
16th to endNight
8%312%49%20%4
768
Page generated at 2017-04-29 06:44:57. Version ac04

Copyright 2017 A. Danko


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