Desert Coyote Observatory
Clear Sky Chart
History

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

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%
23838
34%
74235
30%
23791
79%
23791
50%
35733

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%
757
34%
2457
32%
756
78%
756
50%
1142
January11th to 20thNight
70%
724
36%
2352
34%
724
78%
724
53%
1071
January21st to endNight
61%
792
37%
2574
33%
792
72%
792
44%
1273
February1st to 10thNight
69%
720
36%
2340
35%
720
78%
720
56%
1026
February11th to 20thNight
59%
700
34%
2093
27%
700
70%
700
48%
1051
February21st to endNight
55%
592
41%
1628
29%
592
67%
592
54%
826
March1st to 10thNight
59%
720
39%
1980
27%
720
71%
720
55%
997
March11th to 20thNight
67%
720
38%
1980
27%
720
76%
720
59%
957
March21st to endNight
65%
792
39%
2178
25%
792
75%
792
59%
1063
April1st to 10thNight
73%
719
39%
1979
28%
719
80%
719
66%
907
April11th to 20thNight
63%
533
42%
1777
33%
533
77%
533
61%
713
April21st to endNight
69%
540
45%
1800
38%
540
82%
540
68%
685
May1st to 10thNight
69%
540
40%
1711
32%
540
79%
540
65%
698
May11th to 20thNight
80%
531
41%
1594
36%
531
84%
531
70%
656
May21st to endNight
79%
582
44%
1746
38%
582
84%
582
77%
678
June1st to 10thNight
83%
540
37%
1620
32%
540
84%
540
64%
697
June11th to 20thNight
85%
540
37%
1620
32%
540
87%
540
70%
669
June21st to endNight
82%
540
26%
1620
24%
540
82%
540
47%
819
July1st to 10thNight
79%
525
19%
1575
16%
525
79%
525
35%
898
July11th to 20thNight
74%
522
12%
1566
11%
522
74%
522
23%
1059
July21st to endNight
72%
591
10%
1674
9%
558
71%
558
21%
1162
August1st to 10thNight
81%
537
15%
1602
15%
534
81%
534
31%
972
August11th to 20thNight
78%
534
20%
1670
21%
534
78%
534
31%
1001
August21st to endNight
79%
594
22%
1980
24%
594
79%
594
29%
1176
September1st to 10thNight
76%
676
23%
1936
21%
676
76%
676
33%
1203
September11th to 20thNight
86%
720
38%
1980
32%
720
87%
720
56%
1008
September21st to endNight
84%
720
35%
1980
28%
720
87%
720
59%
988
October1st to 10thNight
83%
720
38%
2096
31%
720
86%
720
60%
978
October11th to 20thNight
81%
720
40%
2160
33%
720
86%
720
64%
948
October21st to endNight
83%
792
45%
2376
38%
792
88%
792
73%
966
November1st to 10thNight
82%
740
45%
2220
39%
740
86%
740
70%
916
November11th to 20thNight
80%
760
43%
2280
38%
760
85%
760
62%
1018
November21st to endNight
64%
760
39%
2384
32%
760
73%
760
49%
1141
December1st to 10thNight
69%
760
38%
2470
37%
760
74%
760
49%
1162
December11th to 20thNight
65%
759
33%
2920
33%
758
73%
758
38%
1450
December21st to endNight
62%
826
24%
4317
34%
817
69%
817
33%
1759

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
332442445%7%63%
74964
Night
331332445%7%65%
74767
TransparencyDay
21%46%12%27%29%
74691
Night
20%47%14%28%28%
74562
SeeingDay
46%17%28%28%17%
13679
Night
4214%43%32%5%
23858

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
34244245%5%6%63%
1708
11th to 20thDay
43243245%47%63%
1620
21st to endDay
4324323446%66%
1782
February1st to 10thDay
4414314335%69%
1620
11th to 20thDay
45%2443344464%
1750
21st to endDay
35%24313325%69%
1628
March1st to 10thDay
342342445%7%62%
1980
11th to 20thDay
3314223345%71%
1980
21st to endDay
3213313445%72%
2178
April1st to 10thDay
121232345%5%72%
1980
11th to 20thDay
221221222480%
2131
21st to endDay
111221222481%
2160
May1st to 10thDay
1212312225%79%
2244
11th to 20thDay
111222224478%
2301
21st to endDay
111221222483%
2530
June1st to 10thDay
2212224346%72%
2340
11th to 20thDay
1212322345%77%
2340
21st to endDay
33245%35%6%5%7%56%
2340
July1st to 10thDay
5%325%6%47%7%7%10%42%
2340
11th to 20thDay
5%5%26%8%5%8%9%9%12%31%
2340
21st to endDay
8%6%47%8%5%7%7%10%11%28%
2545
August1st to 10thDay
6%427%8%5%7%7%8%11%36%
2328
11th to 20thDay
5%5%26%7%46%8%9%11%38%
2228
21st to endDay
4425%7%47%7%8%8%44%
2376
September1st to 10thDay
6%6%26%6%46%5%6%7%46%
2018
11th to 20thDay
33244345%6%7%60%
1980
21st to endDay
321432445%5%67%
1980
October1st to 10thDay
1213323346%71%
1862
11th to 20thDay
2212312335%77%
1800
21st to endDay
222213335%77%
1980
November1st to 10thDay
1112222447%74%
1859
11th to 20thDay
2312224445%72%
1900
21st to endDay
4425%323446%64%
1791
December1st to 10thDay
5%42332345%7%63%
1710
11th to 20thDay
5%7%35%42445%8%55%
2169
21st to endDay
35%2333435%6%63%
3146
January1st to 10thNight
341432445%6%64%
2457
11th to 20thNight
4323323346%68%
2352
21st to endNight
45%2442445%6%61%
2574
February1st to 10thNight
3212324446%69%
2340
11th to 20thNight
5%424323346%64%
2093
21st to endNight
2334433335%67%
1628
March1st to 10thNight
3423323448%64%
1980
11th to 20thNight
2313323345%72%
1980
21st to endNight
2213324445%69%
2178
April1st to 10thNight
1212223345%76%
1979
11th to 20thNight
121212233478%
1777
21st to endNight
1211213225%80%
1800
May1st to 10thNight
2212312225%79%
1711
11th to 20thNight
1112212245%79%
1594
21st to endNight
111111112387%
1746
June1st to 10thNight
3212213346%74%
1620
11th to 20thNight
2212212325%79%
1620
21st to endNight
2214435%6%5%7%60%
1620
July1st to 10thNight
34246%35%7%8%11%47%
1620
11th to 20thNight
3437%8%5%9%8%12%13%29%
1620
21st to endNight
45%37%7%5%7%8%12%16%26%
1773
August1st to 10thNight
35%245%46%7%9%12%42%
1611
11th to 20thNight
5%425%5%46%6%8%11%43%
1670
21st to endNight
5%325%7%5%6%6%9%11%42%
1980
September1st to 10thNight
7%4345%36%6%7%9%46%
1936
11th to 20thNight
3213424347%67%
1980
21st to endNight
3213223346%69%
1980
October1st to 10thNight
2212323446%73%
2096
11th to 20thNight
1113323235%76%
2160
21st to endNight
1111212235%81%
2376
November1st to 10thNight
1112213245%78%
2220
11th to 20thNight
2212222346%72%
2280
21st to endNight
4314323346%66%
2384
December1st to 10thNight
5%323313447%64%
2470
11th to 20thNight
3425%5%35%447%58%
3041
21st to endNight
45%2442345%5%61%
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%27%13%35%21%
1709
11th to 20thDay
21%36%12%33%26%
1620
21st to endDay
22%2316%31%26%
1782
February1st to 10thDay
20%1412%27%35%
1620
11th to 20thDay
24%2412%29%29%
1760
21st to endDay
21%138%29%38%
1628
March1st to 10thDay
22%239%33%30%
1980
11th to 20thDay
17%249%32%37%
1980
21st to endDay
16%239%37%33%
2178
April1st to 10thDay
14%228%37%37%
1980
11th to 20thDay
11%116%29%51%
2134
21st to endDay
10%126%34%46%
2160
May1st to 10thDay
12%136%23%56%
2244
11th to 20thDay
12%248%27%47%
2304
21st to endDay
9%125%27%57%
2530
June1st to 10thDay
13%237%27%47%
2340
11th to 20thDay
12%23419%60%
2340
21st to endDay
25%6%6%10%22%31%
2340
July1st to 10thDay
33%9%12%16%14%16%
2276
11th to 20thDay
40%13%18%18%9%3
2271
21st to endDay
44%13%21%13%8%1
2404
August1st to 10thDay
38%11%15%17%14%5%
2313
11th to 20thDay
35%12%16%17%14%6%
2228
21st to endDay
33%9%13%20%15%9%
2376
September1st to 10thDay
36%8%9%14%20%14%
2018
11th to 20thDay
22%5%8%15%27%24%
1980
21st to endDay
18%46%16%34%22%
1980
October1st to 10thDay
16%36%17%26%31%
1862
11th to 20thDay
13%3412%31%38%
1800
21st to endDay
12%2313%32%39%
1980
November1st to 10thDay
12%2314%38%31%
1859
11th to 20thDay
16%2314%34%31%
1900
21st to endDay
22%2415%30%27%
1791
December1st to 10thDay
22%3417%32%21%
1710
11th to 20thDay
28%26%17%28%19%
2168
21st to endDay
21%35%12%40%19%
3146
January1st to 10thNight
20%27%15%34%22%
2457
11th to 20thNight
19%25%14%30%29%
2352
21st to endNight
25%2414%33%22%
2574
February1st to 10thNight
17%25%15%24%38%
2340
11th to 20thNight
23%1415%29%28%
2094
21st to endNight
20%249%28%37%
1628
March1st to 10thNight
20%1413%31%31%
1980
11th to 20thNight
17%2410%30%37%
1980
21st to endNight
17%25%10%38%29%
2178
April1st to 10thNight
14%1310%38%34%
1979
11th to 20thNight
13%228%31%44%
1777
21st to endNight
11%139%32%45%
1800
May1st to 10thNight
13%137%27%50%
1711
11th to 20thNight
9%35%10%29%45%
1595
21st to endNight
8%117%31%52%
1746
June1st to 10thNight
13%237%31%44%
1620
11th to 20thNight
10%235%24%56%
1620
21st to endNight
22%5%7%11%21%35%
1620
July1st to 10thNight
29%8%16%19%12%16%
1575
11th to 20thNight
39%13%22%17%7%2
1566
21st to endNight
40%15%26%13%5%2
1674
August1st to 10thNight
30%12%19%21%14%5%
1602
11th to 20thNight
32%9%20%17%16%6%
1670
21st to endNight
31%11%18%17%14%8%
1980
September1st to 10thNight
32%9%13%16%18%12%
1936
11th to 20thNight
18%47%22%28%22%
1980
21st to endNight
16%48%16%35%21%
1980
October1st to 10thNight
14%48%15%28%30%
2096
11th to 20thNight
14%2416%25%39%
2160
21st to endNight
9%2415%31%40%
2376
November1st to 10thNight
10%2416%37%31%
2220
11th to 20thNight
14%2317%33%30%
2280
21st to endNight
21%2415%33%25%
2384
December1st to 10thNight
22%25%20%29%22%
2470
11th to 20thNight
26%35%18%31%17%
3041
21st to endNight
23%35%13%36%20%
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
5%5%26%34%25%6%
270
11th to 20thDay
5%418%40%26%7%
240
21st to endDay
27%22%38%25%6%
264
February1st to 10thDay
45%18%33%28%13%
240
11th to 20thDay
9%13%32%29%14%2
407
21st to endDay
7%17%32%31%10%3
346
March1st to 10thDay
5%14%32%30%15%5%
420
11th to 20thDay
6%12%27%26%19%10%
420
21st to endDay
417%29%30%15%5%
462
April1st to 10thDay
29%29%30%21%9%
420
11th to 20thDay
410%32%28%18%8%
412
21st to endDay
112%27%30%20%9%
420
May1st to 10thDay
312%26%26%21%12%
423
11th to 20thDay
18%21%35%23%13%
448
21st to endDay
25%24%36%25%8%
485
June1st to 10thDay
4316%35%26%16%
450
11th to 20thDay
2215%32%33%16%
450
21st to endDay
426%33%34%21%
450
July1st to 10thDay
5%2421%36%32%
446
11th to 20thDay
6%2217%36%37%
444
21st to endDay
7%2316%34%38%
487
August1st to 10thDay
7%113%38%41%
447
11th to 20thDay
44316%36%37%
437
21st to endDay
32215%37%41%
495
September1st to 10thDay
9%16%26%34%25%
450
11th to 20thDay
5%2425%38%26%
450
21st to endDay
3411%25%39%18%
450
October1st to 10thDay
1315%26%33%22%
332
11th to 20thDay
3212%27%33%23%
270
21st to endDay
1214%31%29%22%
297
November1st to 10thDay
35%17%32%31%11%
270
11th to 20thDay
3314%33%35%13%
270
21st to endDay
5%427%32%25%8%
270
December1st to 10thDay
6%321%31%29%10%
270
11th to 20thDay
7%321%35%29%5%
270
21st to endDay
10%7%24%30%24%6%
297
January1st to 10thNight
3216%54%23%2
760
11th to 20thNight
4316%48%27%2
724
21st to endNight
6%222%47%21%2
792
February1st to 10thNight
3320%46%24%4
720
11th to 20thNight
6%424%48%16%3
704
21st to endNight
36%31%44%15%1
592
March1st to 10thNight
3329%49%14%2
720
11th to 20thNight
3424%41%25%4
720
21st to endNight
3324%47%21%2
792
April1st to 10thNight
1220%55%20%2
719
11th to 20thNight
3427%47%18%1
533
21st to endNight
1324%55%16%1
540
May1st to 10thNight
3222%50%23%1
540
11th to 20thNight
1114%52%30%2
531
21st to endNight
2215%52%28%1
584
June1st to 10thNight
418%52%34%1
540
11th to 20thNight
217%52%37%1
540
21st to endNight
22439%49%4
540
July1st to 10thNight
42230%55%6%
525
11th to 20thNight
41220%60%12%
522
21st to endNight
5%3217%59%14%
591
August1st to 10thNight
41117%62%15%
537
11th to 20thNight
43119%59%14%
534
21st to endNight
6%220%60%12%
594
September1st to 10thNight
8%1323%55%9%
676
11th to 20thNight
41232%53%8%
720
21st to endNight
326%43%41%5%
720
October1st to 10thNight
219%48%34%6%
720
11th to 20thNight
2112%45%34%6%
720
21st to endNight
1211%44%36%7%
792
November1st to 10thNight
1211%46%33%6%
740
11th to 20thNight
3111%49%32%4
760
21st to endNight
6%320%47%21%4
760
December1st to 10thNight
6%216%50%22%4
760
11th to 20thNight
3420%52%19%3
760
21st to endNight
6%321%47%19%4
836
Page generated at 2024-01-08 09:14:21. Version ac07

Copyright 2024 Attilla Danko


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