Scottsdale
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Scottsdale clear sky chart from 2005-11-06 to 2024-01-16.

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
76%
24088
36%
74420
33%
24042
81%
24042
55%
34719

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 10thNight
72%
758
33%
2457
33%
756
77%
756
46%
1202
January11th to 20thNight
70%
744
38%
2418
36%
744
77%
744
48%
1148
January21st to endNight
64%
792
36%
2574
33%
792
73%
792
43%
1311
February1st to 10thNight
73%
720
37%
2261
36%
720
80%
720
54%
1033
February11th to 20thNight
65%
700
34%
2099
30%
700
73%
700
46%
1079
February21st to endNight
62%
592
36%
1762
33%
592
69%
592
48%
887
March1st to 10thNight
65%
720
38%
1980
30%
720
73%
720
58%
966
March11th to 20thNight
72%
720
38%
1980
32%
720
78%
720
58%
980
March21st to endNight
71%
792
39%
2178
29%
792
78%
792
59%
1055
April1st to 10thNight
75%
720
36%
1980
26%
720
82%
720
63%
929
April11th to 20thNight
68%
611
39%
1855
30%
611
78%
611
65%
773
April21st to endNight
72%
540
47%
1643
37%
540
81%
540
71%
659
May1st to 10thNight
74%
540
42%
1620
34%
540
80%
540
68%
672
May11th to 20thNight
78%
531
41%
1594
34%
531
82%
531
71%
653
May21st to endNight
79%
582
41%
1746
32%
582
83%
582
77%
679
June1st to 10thNight
87%
540
37%
1620
32%
540
88%
540
72%
653
June11th to 20thNight
88%
540
40%
1620
34%
540
91%
540
87%
586
June21st to endNight
86%
540
32%
1620
28%
540
87%
540
66%
691
July1st to 10thNight
85%
525
27%
1575
23%
525
85%
525
51%
778
July11th to 20thNight
86%
522
28%
1566
23%
522
86%
522
50%
781
July21st to endNight
80%
591
25%
1674
21%
558
80%
558
37%
978
August1st to 10thNight
88%
537
29%
1602
24%
534
88%
534
50%
804
August11th to 20thNight
82%
534
34%
1602
31%
534
82%
534
44%
851
August21st to endNight
85%
702
31%
2006
30%
702
85%
702
47%
1077
September1st to 10thNight
82%
720
33%
1980
30%
720
83%
720
52%
1039
September11th to 20thNight
84%
720
42%
1980
36%
720
87%
720
69%
894
September21st to endNight
82%
720
39%
1980
31%
720
86%
720
64%
921
October1st to 10thNight
78%
720
40%
2011
32%
720
82%
720
63%
935
October11th to 20thNight
82%
720
44%
2160
39%
720
86%
720
74%
866
October21st to endNight
80%
792
46%
2376
38%
792
87%
792
74%
950
November1st to 10thNight
81%
740
43%
2220
40%
740
85%
740
66%
949
November11th to 20thNight
80%
760
42%
2428
40%
760
86%
760
63%
1020
November21st to endNight
70%
760
39%
2470
36%
760
78%
760
53%
1116
December1st to 10thNight
72%
760
38%
2470
38%
760
77%
760
49%
1167
December11th to 20thNight
67%
758
33%
2943
35%
758
73%
758
33%
1559
December21st to endNight
67%
825
23%
4370
35%
817
72%
817
27%
2078

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
3213323346%69%
74977
Night
4213323346%68%
74875
TransparencyDay
16%35%12%24%40%
74704
Night
17%35%11%22%41%
74670
SeeingDay
4416%33%32%11%
13866
Night
4212%44%34%3
24109

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 10thDay
6%323433337%64%
1708
11th to 20thDay
6%323312346%67%
1669
21st to endDay
7%423323247%64%
1782
February1st to 10thDay
4413212347%69%
1696
11th to 20thDay
7%424323446%61%
1750
21st to endDay
5%324323446%64%
1493
March1st to 10thDay
5%31242445%7%63%
1980
11th to 20thDay
5%323313346%67%
1980
21st to endDay
4313323335%70%
2178
April1st to 10thDay
2113223347%72%
1980
11th to 20thDay
2211213335%77%
2050
21st to endDay
2111212246%79%
2312
May1st to 10thDay
1112212235%81%
2340
11th to 20thDay
111121233480%
2301
21st to endDay
21111112486%
2530
June1st to 10thDay
1111113235%82%
2340
11th to 20thDay
111111121388%
2340
21st to endDay
1111212235%79%
2340
July1st to 10thDay
21133245%6%7%66%
2340
11th to 20thDay
3214435%7%8%11%52%
2340
21st to endDay
5%325%5%45%5%9%11%47%
2545
August1st to 10thDay
3313325%5%6%8%60%
2328
11th to 20thDay
33134245%7%10%57%
2299
21st to endDay
22134235%5%8%64%
2346
September1st to 10thDay
421341345%7%65%
1980
11th to 20thDay
221121223479%
1980
21st to endDay
211222323477%
1980
October1st to 10thDay
3112223346%73%
1948
11th to 20thDay
11111123485%
1800
21st to endDay
1112212335%80%
1980
November1st to 10thDay
2112212246%76%
1859
11th to 20thDay
221332233475%
1748
21st to endDay
6%313312246%66%
1710
December1st to 10thDay
7%3144335%45%61%
1710
11th to 20thDay
6%425%6%3446%7%54%
2169
21st to endDay
9%5%25%42345%5%54%
3146
January1st to 10thNight
6%3233245%5%6%61%
2457
11th to 20thNight
6%313323335%67%
2418
21st to endNight
8%324424345%62%
2574
February1st to 10thNight
5%313223336%69%
2261
11th to 20thNight
7%423423445%63%
2098
21st to endNight
7%313324426%65%
1762
March1st to 10thNight
421332335%7%66%
1980
11th to 20thNight
6%312322335%69%
1980
21st to endNight
5%21332335%7%68%
2178
April1st to 10thNight
2112323447%70%
1980
11th to 20thNight
221221233477%
1855
21st to endNight
2111212225%82%
1643
May1st to 10thNight
1112212345%77%
1620
11th to 20thNight
211221223481%
1594
21st to endNight
21111122386%
1746
June1st to 10thNight
1111213237%78%
1620
11th to 20thNight
1111225%87%
1620
21st to endNight
2112313235%76%
1620
July1st to 10thNight
1213436%5%6%8%61%
1620
11th to 20thNight
22134445%8%12%55%
1620
21st to endNight
4325%6%45%7%8%13%43%
1773
August1st to 10thNight
2213335%5%7%11%57%
1611
11th to 20thNight
23245%346%6%10%55%
1602
21st to endNight
2313446%5%6%9%57%
2006
September1st to 10thNight
3313425%46%8%59%
1980
11th to 20thNight
2212313245%76%
1980
21st to endNight
321222334474%
1980
October1st to 10thNight
2212323335%74%
2011
11th to 20thNight
2211211235%82%
2160
21st to endNight
111221223482%
2376
November1st to 10thNight
3212212346%74%
2220
11th to 20thNight
2212222235%76%
2428
21st to endNight
5%213323446%67%
2470
December1st to 10thNight
7%21332335%7%64%
2470
11th to 20thNight
8%5%25%5%2445%6%54%
3041
21st to endNight
9%5%24434445%56%
4521

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 10thDay
22%36%17%30%23%
1709
11th to 20thDay
20%45%13%28%30%
1669
21st to endDay
22%35%16%27%28%
1782
February1st to 10thDay
17%35%16%24%35%
1696
11th to 20thDay
24%36%13%25%29%
1760
21st to endDay
20%3413%29%30%
1493
March1st to 10thDay
20%35%11%26%34%
1980
11th to 20thDay
18%35%11%26%37%
1980
21st to endDay
18%249%33%33%
2178
April1st to 10thDay
12%229%34%40%
1980
11th to 20thDay
11%238%25%52%
2053
21st to endDay
9%138%24%55%
2312
May1st to 10thDay
9%138%24%55%
2340
11th to 20thDay
9%239%21%56%
2304
21st to endDay
7%12421%65%
2530
June1st to 10thDay
8%115%20%65%
2340
11th to 20thDay
5%1129%81%
2340
21st to endDay
10%235%14%66%
2340
July1st to 10thDay
15%5%7%10%18%46%
2276
11th to 20thDay
20%7%15%21%22%14%
2271
21st to endDay
26%9%14%22%17%13%
2404
August1st to 10thDay
19%6%10%16%17%32%
2313
11th to 20thDay
18%7%12%19%22%22%
2299
21st to endDay
17%6%8%17%27%26%
2346
September1st to 10thDay
18%47%13%23%35%
1980
11th to 20thDay
10%248%28%48%
1980
21st to endDay
12%346%23%52%
1980
October1st to 10thDay
13%35%12%23%43%
1948
11th to 20thDay
6%246%24%58%
1800
21st to endDay
10%239%26%49%
1980
November1st to 10thDay
9%2413%31%40%
1859
11th to 20thDay
14%2310%27%43%
1748
21st to endDay
20%3411%26%36%
1710
December1st to 10thDay
25%35%14%23%29%
1710
11th to 20thDay
27%5%7%19%22%20%
2168
21st to endDay
29%5%7%19%26%14%
3146
January1st to 10thNight
23%46%14%28%26%
2457
11th to 20thNight
21%3313%27%32%
2418
21st to endNight
26%35%13%25%29%
2574
February1st to 10thNight
18%2412%25%39%
2261
11th to 20thNight
24%35%13%24%31%
2099
21st to endNight
23%35%10%26%34%
1762
March1st to 10thNight
17%35%11%24%40%
1980
11th to 20thNight
18%249%24%43%
1980
21st to endNight
16%3410%32%35%
2178
April1st to 10thNight
14%339%25%46%
1980
11th to 20thNight
11%247%23%54%
1855
21st to endNight
9%226%20%60%
1643
May1st to 10thNight
10%238%22%54%
1620
11th to 20thNight
10%137%18%60%
1595
21st to endNight
8%115%16%70%
1746
June1st to 10thNight
10%12414%69%
1620
11th to 20thNight
312410%79%
1620
21st to endNight
12%2448%70%
1620
July1st to 10thNight
18%6%8%10%14%44%
1575
11th to 20thNight
18%7%14%21%22%18%
1566
21st to endNight
27%9%13%18%16%15%
1674
August1st to 10thNight
19%6%9%18%15%32%
1602
11th to 20thNight
22%7%11%17%17%25%
1602
21st to endNight
22%6%7%14%23%27%
2006
September1st to 10thNight
20%5%9%17%17%32%
1980
11th to 20thNight
11%25%9%23%49%
1980
21st to endNight
12%447%18%55%
1980
October1st to 10thNight
14%3412%20%47%
2011
11th to 20thNight
9%136%20%61%
2160
21st to endNight
9%249%20%57%
2376
November1st to 10thNight
13%249%28%46%
2220
11th to 20thNight
13%2310%24%47%
2428
21st to endNight
18%35%11%26%38%
2470
December1st to 10thNight
21%3417%21%34%
2470
11th to 20thNight
30%46%13%25%22%
3041
21st to endNight
27%6%9%16%23%18%
4521

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 10thDay
11%219%39%27%4
270
11th to 20thDay
13%214%35%30%5%
257
21st to endDay
6%6%19%36%25%9%
264
February1st to 10thDay
5%5%21%32%28%9%
316
11th to 20thDay
11%9%25%34%20%2
415
21st to endDay
10%9%30%34%14%3
346
March1st to 10thDay
8%9%28%36%14%5%
420
11th to 20thDay
7%8%24%31%20%10%
420
21st to endDay
6%11%28%33%19%3
462
April1st to 10thDay
5%9%23%34%22%8%
420
11th to 20thDay
311%26%36%20%5%
412
21st to endDay
49%26%31%23%7%
420
May1st to 10thDay
28%24%34%25%7%
423
11th to 20thDay
25%21%37%28%7%
448
21st to endDay
16%22%39%26%6%
485
June1st to 10thDay
2314%38%34%9%
450
11th to 20thDay
1219%34%32%12%
450
21st to endDay
2111%36%41%10%
450
July1st to 10thDay
16%30%47%15%
446
11th to 20thDay
45%25%44%22%
444
21st to endDay
5%1322%44%26%
487
August1st to 10thDay
31423%46%22%
447
11th to 20thDay
316%24%43%23%
437
21st to endDay
11321%48%27%
495
September1st to 10thDay
429%29%42%15%
450
11th to 20thDay
3210%31%41%13%
450
21st to endDay
4212%33%33%15%
450
October1st to 10thDay
4118%34%34%9%
418
11th to 20thDay
3313%33%34%14%
270
21st to endDay
15%14%27%40%13%
297
November1st to 10thDay
3313%38%36%8%
270
11th to 20thDay
4412%37%33%10%
270
21st to endDay
6%419%37%26%8%
270
December1st to 10thDay
9%29%44%29%7%
270
11th to 20thDay
5%319%41%27%6%
270
21st to endDay
13%6%18%36%23%4
297
January1st to 10thNight
6%114%51%26%2
760
11th to 20thNight
8%214%47%27%2
744
21st to endNight
10%217%47%21%2
792
February1st to 10thNight
6%116%48%27%3
720
11th to 20thNight
9%219%50%19%1
704
21st to endNight
9%318%49%19%1
592
March1st to 10thNight
4322%53%17%1
720
11th to 20thNight
7%315%44%26%6%
720
21st to endNight
4417%47%27%2
792
April1st to 10thNight
3215%54%24%2
720
11th to 20thNight
3422%47%24%1
611
21st to endNight
3221%46%25%2
540
May1st to 10thNight
1417%48%27%2
540
11th to 20thNight
2215%49%31%1
531
21st to endNight
3215%50%29%2
584
June1st to 10thNight
228%54%33%2
540
11th to 20thNight
18%55%34%1
540
21st to endNight
215%46%43%2
540
July1st to 10thNight
26%39%51%3
525
11th to 20thNight
4325%62%5%
522
21st to endNight
5%1320%62%9%
591
August1st to 10thNight
21223%62%10%
537
11th to 20thNight
21429%59%5%
534
21st to endNight
2424%61%9%
702
September1st to 10thNight
416%29%54%6%
720
11th to 20thNight
218%39%46%4
720
21st to endNight
329%42%39%6%
720
October1st to 10thNight
3112%50%33%2
720
11th to 20thNight
2211%47%37%3
720
21st to endNight
1114%40%37%6%
792
November1st to 10thNight
4110%47%35%3
740
11th to 20thNight
313%48%34%3
760
21st to endNight
6%216%45%28%3
760
December1st to 10thNight
6%213%46%31%1
760
11th to 20thNight
10%312%49%25%1
760
21st to endNight
9%313%49%22%3
836
Page generated at 2024-01-13 17:28:32. Version ac07

Copyright 2024 Attilla Danko


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