Cordes Lakes Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cordes Lakes Observatory clear sky chart from 2005-11-06 to 2024-03-08.

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%
24272
35%
79569
29%
24185
79%
24185
49%
37299

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
63%
749
37%
3992
28%
736
75%
736
31%
1651
January11th to 20thNight
62%
751
43%
3905
32%
740
73%
740
40%
1361
January21st to endNight
54%
830
23%
4305
27%
814
67%
814
22%
2391
February1st to 10thNight
61%
760
35%
2396
29%
760
74%
760
47%
1174
February11th to 20thNight
59%
740
35%
2219
28%
740
72%
740
48%
1125
February21st to endNight
56%
628
34%
1884
29%
628
65%
628
44%
983
March1st to 10thNight
59%
750
36%
2069
26%
750
69%
750
52%
1046
March11th to 20thNight
65%
720
36%
1980
27%
720
73%
720
52%
1016
March21st to endNight
64%
792
36%
2178
24%
792
74%
792
54%
1079
April1st to 10thNight
66%
720
33%
1980
20%
720
76%
720
59%
962
April11th to 20thNight
59%
611
39%
1835
24%
611
72%
611
58%
808
April21st to endNight
66%
540
46%
1620
32%
540
78%
540
72%
662
May1st to 10thNight
74%
540
40%
1620
30%
540
80%
540
62%
697
May11th to 20thNight
74%
531
40%
1594
33%
531
79%
531
65%
671
May21st to endNight
78%
582
40%
1746
30%
582
83%
582
74%
695
June1st to 10thNight
83%
540
37%
1620
32%
540
84%
540
72%
657
June11th to 20thNight
84%
540
38%
1620
32%
540
86%
540
78%
626
June21st to endNight
85%
540
34%
1620
30%
540
86%
540
66%
692
July1st to 10thNight
88%
525
28%
1575
23%
525
88%
525
52%
766
July11th to 20thNight
88%
522
26%
1566
23%
522
88%
522
49%
786
July21st to endNight
79%
591
23%
1674
20%
558
80%
558
35%
978
August1st to 10thNight
89%
537
28%
1602
24%
534
89%
534
48%
811
August11th to 20thNight
87%
534
31%
1602
27%
534
87%
534
45%
824
August21st to endNight
87%
701
32%
1980
28%
701
87%
701
48%
1052
September1st to 10thNight
82%
720
32%
1980
28%
720
84%
720
51%
1044
September11th to 20thNight
87%
720
42%
1980
35%
720
90%
720
68%
898
September21st to endNight
79%
720
40%
1980
30%
720
85%
720
64%
925
October1st to 10thNight
74%
720
37%
2006
28%
720
80%
720
57%
985
October11th to 20thNight
80%
720
43%
2160
38%
720
85%
720
70%
885
October21st to endNight
76%
792
45%
2376
36%
792
85%
792
68%
984
November1st to 10thNight
77%
740
41%
2224
35%
740
84%
740
62%
995
November11th to 20thNight
76%
760
41%
2470
37%
760
84%
760
61%
1029
November21st to endNight
65%
760
38%
2470
33%
760
76%
760
49%
1135
December1st to 10thNight
67%
760
36%
2470
33%
760
74%
760
46%
1184
December11th to 20thNight
62%
758
32%
2936
29%
758
71%
758
32%
1586
December21st to endNight
56%
828
22%
4335
27%
817
66%
817
24%
2136

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
331332345%6%67%
79039
Night
4313323446%68%
80592
TransparencyDay
19%5%6%15%27%28%
78766
Night
18%46%15%27%29%
80387
SeeingDay
5%10%24%33%22%7%
14048
Night
4316%40%32%5%
24314

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
3425%423345%64%
2858
11th to 20thDay
331343445%466%
2860
21st to endDay
10%6%2442445%7%52%
3146
February1st to 10thDay
3424423446%65%
1781
11th to 20thDay
5%32442445%6%61%
1850
21st to endDay
43235%34447%62%
1570
March1st to 10thDay
431342445%7%62%
2049
11th to 20thDay
432332345%6%65%
1980
21st to endDay
3212424446%67%
2178
April1st to 10thDay
211322345%8%68%
1980
11th to 20thDay
1212223337%74%
2066
21st to endDay
2112212346%75%
2340
May1st to 10thDay
2112323346%74%
2340
11th to 20thDay
2211223446%74%
2301
21st to endDay
121211233481%
2530
June1st to 10thDay
111112235%82%
2340
11th to 20thDay
11111112388%
2340
21st to endDay
111221234478%
2340
July1st to 10thDay
1212335%5%6%7%64%
2340
11th to 20thDay
33245%46%7%8%10%48%
2340
21st to endDay
43346%47%7%9%12%41%
2545
August1st to 10thDay
3314435%6%6%8%58%
2328
11th to 20thDay
3213435%6%8%11%53%
2299
21st to endDay
42134347%6%8%57%
2369
September1st to 10thDay
33124245%6%8%61%
1980
11th to 20thDay
3111212335%78%
1980
21st to endDay
311322234475%
1980
October1st to 10thDay
221332335%6%71%
1954
11th to 20thDay
21121223482%
1800
21st to endDay
111211233480%
1980
November1st to 10thDay
1212223346%74%
1850
11th to 20thDay
121221235%5%75%
1710
21st to endDay
5%323312345%69%
1710
December1st to 10thDay
6%423324436%62%
1710
11th to 20thDay
45%25%5%45%5%6%8%50%
2169
21st to endDay
9%5%25%423346%55%
3146
January1st to 10thNight
4423424446%63%
4097
11th to 20thNight
3212323337%71%
4110
21st to endNight
11%8%34423446%51%
4521
February1st to 10thNight
4413323346%67%
2396
11th to 20thNight
5%423323347%65%
2218
21st to endNight
6%5%1332346%6%61%
1884
March1st to 10thNight
432322445%7%64%
2069
11th to 20thNight
6%313323335%68%
1980
21st to endNight
32233135%46%68%
2178
April1st to 10thNight
311222335%6%71%
1980
11th to 20thNight
1213222335%76%
1835
21st to endNight
1111212336%80%
1620
May1st to 10thNight
21122245%6%75%
1620
11th to 20thNight
121221223480%
1594
21st to endNight
21211122484%
1746
June1st to 10thNight
111212335%81%
1620
11th to 20thNight
11111123386%
1620
21st to endNight
211222322478%
1620
July1st to 10thNight
2113435%6%6%8%63%
1620
11th to 20thNight
12233245%9%12%59%
1620
21st to endNight
3425%5%46%7%7%10%46%
1773
August1st to 10thNight
1212425%6%8%9%59%
1611
11th to 20thNight
2113336%7%8%10%56%
1602
21st to endNight
2214435%6%6%9%59%
1980
September1st to 10thNight
331342446%9%61%
1980
11th to 20thNight
221221234477%
1980
21st to endNight
2212222345%76%
1980
October1st to 10thNight
3213323345%71%
2006
11th to 20thNight
211121222482%
2160
21st to endNight
1112212335%80%
2376
November1st to 10thNight
2213222345%74%
2224
11th to 20thNight
221221233477%
2470
21st to endNight
5%21222435%6%69%
2470
December1st to 10thNight
5%31332345%6%65%
2470
11th to 20thNight
6%4245%3446%7%55%
3041
21st to endNight
8%5%245%3445%5%57%
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
24%45%19%35%14%
2859
11th to 20thDay
23%45%28%25%16%
2860
21st to endDay
32%6%6%15%30%11%
3146
February1st to 10thDay
22%46%14%27%27%
1781
11th to 20thDay
25%45%17%27%22%
1860
21st to endDay
24%46%18%28%21%
1570
March1st to 10thDay
22%4417%28%24%
2049
11th to 20thDay
21%45%16%32%23%
1980
21st to endDay
19%45%17%37%18%
2178
April1st to 10thDay
16%45%16%34%26%
1980
11th to 20thDay
12%4413%32%35%
2069
21st to endDay
12%3413%34%34%
2340
May1st to 10thDay
12%45%13%32%34%
2340
11th to 20thDay
12%35%13%30%36%
2304
21st to endDay
9%2311%31%43%
2530
June1st to 10thDay
9%227%32%48%
2340
11th to 20thDay
5%115%20%67%
2340
21st to endDay
11%346%21%55%
2340
July1st to 10thDay
16%6%8%14%19%38%
2276
11th to 20thDay
25%12%15%18%19%12%
2271
21st to endDay
29%12%18%18%14%9%
2404
August1st to 10thDay
22%7%11%16%18%26%
2313
11th to 20thDay
21%8%14%21%19%18%
2299
21st to endDay
22%8%10%17%27%16%
2369
September1st to 10thDay
20%6%9%15%24%26%
1980
11th to 20thDay
11%35%12%33%36%
1980
21st to endDay
13%35%10%30%38%
1980
October1st to 10thDay
16%46%17%23%35%
1954
11th to 20thDay
9%2410%30%46%
1800
21st to endDay
11%25%14%30%38%
1980
November1st to 10thDay
13%3418%34%28%
1850
11th to 20thDay
13%3416%30%34%
1710
21st to endDay
20%3415%31%27%
1710
December1st to 10thDay
26%5%6%16%23%25%
1710
11th to 20thDay
31%5%9%18%19%17%
2168
21st to endDay
30%6%6%18%29%11%
3146
January1st to 10thNight
23%45%17%36%15%
4097
11th to 20thNight
16%46%29%31%14%
4110
21st to endNight
34%6%412%29%15%
4521
February1st to 10thNight
21%46%14%27%29%
2396
11th to 20thNight
22%35%18%28%24%
2219
21st to endNight
24%45%14%30%23%
1884
March1st to 10thNight
19%36%16%29%26%
2069
11th to 20thNight
20%35%14%30%28%
1980
21st to endNight
17%5%6%16%35%21%
2178
April1st to 10thNight
15%35%14%33%29%
1980
11th to 20thNight
13%3310%32%38%
1835
21st to endNight
9%15%13%34%37%
1620
May1st to 10thNight
12%35%13%28%39%
1620
11th to 20thNight
11%3410%29%43%
1595
21st to endNight
8%2210%32%47%
1746
June1st to 10thNight
9%226%24%57%
1620
11th to 20thNight
7%22416%70%
1620
21st to endNight
12%226%17%61%
1620
July1st to 10thNight
17%6%8%11%17%40%
1575
11th to 20thNight
18%8%16%20%24%15%
1566
21st to endNight
28%9%16%20%15%11%
1674
August1st to 10thNight
18%9%11%17%17%29%
1602
11th to 20thNight
18%10%14%20%17%21%
1602
21st to endNight
21%6%9%20%26%19%
1980
September1st to 10thNight
19%6%11%19%19%26%
1980
11th to 20thNight
11%36%11%30%39%
1980
21st to endNight
13%439%29%42%
1980
October1st to 10thNight
17%35%15%22%37%
2006
11th to 20thNight
10%1310%25%50%
2160
21st to endNight
10%35%11%27%45%
2376
November1st to 10thNight
14%2415%35%29%
2224
11th to 20thNight
13%3415%29%37%
2470
21st to endNight
19%3413%29%31%
2470
December1st to 10thNight
21%47%17%23%28%
2470
11th to 20thNight
30%5%7%15%25%18%
3041
21st to endNight
28%8%6%18%27%14%
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
13%9%24%34%19%1
270
11th to 20thDay
13%6%22%38%16%4
270
21st to endDay
8%10%28%30%18%5%
297
February1st to 10thDay
5%14%29%31%17%3
341
11th to 20thDay
9%16%36%27%13%
455
21st to endDay
9%24%33%25%8%1
382
March1st to 10thDay
8%22%30%27%10%2
449
11th to 20thDay
8%18%27%27%15%4
420
21st to endDay
7%22%35%24%10%2
462
April1st to 10thDay
6%14%36%25%15%5%
420
11th to 20thDay
6%20%37%23%10%4
412
21st to endDay
419%35%25%12%5%
420
May1st to 10thDay
315%35%28%16%3
423
11th to 20thDay
313%32%29%17%6%
448
21st to endDay
5%13%31%30%17%4
485
June1st to 10thDay
17%27%38%21%5%
450
11th to 20thDay
27%30%34%19%8%
450
21st to endDay
2324%42%22%7%
450
July1st to 10thDay
1215%44%28%11%
446
11th to 20thDay
417%40%29%19%
444
21st to endDay
5%15%32%35%22%
487
August1st to 10thDay
2111%40%32%15%
447
11th to 20thDay
329%38%30%18%
437
21st to endDay
316%34%36%20%
495
September1st to 10thDay
4314%34%31%12%
450
11th to 20thDay
3319%38%30%6%
450
21st to endDay
47%18%37%24%10%
450
October1st to 10thDay
39%27%28%24%8%
424
11th to 20thDay
3421%30%31%9%
270
21st to endDay
5%8%16%31%30%9%
297
November1st to 10thDay
47%18%42%23%6%
270
11th to 20thDay
37%19%37%26%7%
270
21st to endDay
8%10%23%31%22%5%
270
December1st to 10thDay
10%9%20%37%23%2
270
11th to 20thDay
37%27%41%19%2
270
21st to endDay
15%13%23%29%18%2
297
January1st to 10thNight
6%421%45%19%4
760
11th to 20thNight
7%5%22%42%22%3
760
21st to endNight
10%6%24%39%19%2
836
February1st to 10thNight
7%5%23%42%21%2
760
11th to 20thNight
7%5%25%47%16%1
744
21st to endNight
9%7%26%41%14%3
628
March1st to 10thNight
5%7%27%45%16%1
750
11th to 20thNight
8%418%39%27%4
720
21st to endNight
46%23%43%22%2
792
April1st to 10thNight
3422%47%22%3
720
11th to 20thNight
28%25%39%24%2
611
21st to endNight
1427%40%26%3
540
May1st to 10thNight
2416%51%25%3
540
11th to 20thNight
2415%44%32%3
531
21st to endNight
2215%45%32%4
584
June1st to 10thNight
2212%45%37%3
540
11th to 20thNight
1111%48%35%4
540
21st to endNight
216%37%48%5%
540
July1st to 10thNight
2334%54%7%
525
11th to 20thNight
2216%66%15%
522
21st to endNight
31218%60%15%
591
August1st to 10thNight
11122%60%15%
537
11th to 20thNight
11322%62%11%
534
21st to endNight
21221%58%15%
701
September1st to 10thNight
326%28%50%11%
720
11th to 20thNight
36%38%48%6%
720
21st to endNight
3212%37%42%6%
720
October1st to 10thNight
4314%43%34%2
720
11th to 20thNight
1212%48%32%4
720
21st to endNight
3315%38%33%9%
792
November1st to 10thNight
4213%46%30%5%
740
11th to 20thNight
2316%46%28%4
760
21st to endNight
6%5%20%40%26%3
760
December1st to 10thNight
8%5%17%42%28%1
760
11th to 20thNight
10%419%46%20%2
760
21st to endNight
10%324%43%16%3
836
Page generated at 2024-03-05 05:23:58. Version ac07

Copyright © 2024 Attilla Danko.


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