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Colorado National Monument
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Colorado National Monument 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
68%
24440
26%
74608
22%
24398
71%
24398
40%
40514

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
67%
794
19%
2495
18%
794
69%
794
32%
1486
January11th to 20thNight
64%
740
23%
2405
21%
740
68%
740
34%
1346
January21st to endNight
66%
792
23%
2574
24%
792
68%
792
31%
1507
February1st to 10thNight
64%
720
20%
2340
19%
720
68%
720
35%
1321
February11th to 20thNight
58%
700
19%
2273
17%
700
62%
700
30%
1333
February21st to endNight
56%
592
28%
1757
23%
592
62%
592
34%
1045
March1st to 10thNight
58%
720
25%
1980
19%
720
63%
720
38%
1162
March11th to 20thNight
66%
720
28%
1980
22%
720
69%
720
43%
1114
March21st to endNight
59%
792
22%
2178
15%
792
64%
792
33%
1368
April1st to 10thNight
53%
575
24%
1835
19%
575
61%
575
34%
1035
April11th to 20thNight
55%
533
24%
1777
20%
533
63%
533
32%
964
April21st to endNight
58%
540
25%
1738
19%
540
66%
540
36%
937
May1st to 10thNight
59%
540
24%
1620
19%
540
64%
540
36%
924
May11th to 20thNight
69%
531
25%
1595
21%
531
72%
531
42%
861
May21st to endNight
62%
582
26%
1565
19%
582
68%
582
44%
873
June1st to 10thNight
73%
540
30%
1440
24%
540
76%
540
59%
720
June11th to 20thNight
68%
540
31%
1440
25%
540
72%
540
54%
746
June21st to endNight
82%
540
32%
1440
29%
540
84%
540
66%
689
July1st to 10thNight
80%
525
25%
1440
23%
525
81%
525
50%
765
July11th to 20thNight
85%
522
24%
1566
22%
522
86%
522
49%
778
July21st to endNight
83%
591
23%
1674
21%
558
83%
558
40%
942
August1st to 10thNight
80%
537
24%
1602
21%
534
80%
534
43%
868
August11th to 20thNight
80%
534
33%
1602
30%
534
82%
534
51%
790
August21st to endNight
81%
594
32%
1973
36%
594
82%
594
46%
959
September1st to 10thNight
79%
540
36%
1800
39%
540
82%
540
49%
834
September11th to 20thNight
83%
622
35%
1882
36%
622
84%
622
54%
912
September21st to endNight
75%
720
37%
2017
28%
720
80%
720
57%
997
October1st to 10thNight
71%
720
30%
2160
22%
720
75%
720
47%
1103
October11th to 20thNight
74%
720
36%
2160
27%
720
79%
720
55%
1013
October21st to endNight
68%
792
36%
2376
28%
792
73%
792
47%
1211
November1st to 10thNight
71%
740
35%
2220
27%
740
76%
740
51%
1076
November11th to 20thNight
70%
912
33%
2560
25%
912
74%
912
54%
1282
November21st to endNight
64%
950
26%
2660
20%
950
68%
950
43%
1492
December1st to 10thNight
65%
950
19%
2660
16%
950
66%
950
37%
1583
December11th to 20thNight
60%
949
19%
3144
14%
948
63%
948
28%
1874
December21st to endNight
55%
1031
9%
4680
13%
1026
57%
1026
19%
2604

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
34244345%6%8%59%
74678
Night
34244345%6%8%57%
75130
TransparencyDay
22%7%12%23%22%14%
74400
Night
24%8%13%23%21%12%
74929
SeeingDay
47%21%33%26%8%
14173
Night
5%318%45%26%3
24465

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
25%26%6%45%6%7%10%48%
1684
11th to 20thDay
2425%5%45%6%6%8%56%
1665
21st to endDay
45%35%6%35%448%53%
1782
February1st to 10thDay
25%25%6%46%5%5%8%52%
1620
11th to 20thDay
37%26%5%45%5%6%7%50%
1575
21st to endDay
36%26%6%36%5%5%7%52%
1494
March1st to 10thDay
36%35%436%5%6%7%52%
1980
11th to 20thDay
26%235%35%5%6%8%55%
1980
21st to endDay
35%25%5%36%6%6%8%51%
2178
April1st to 10thDay
4423435%6%6%8%54%
2124
11th to 20thDay
35%25%6%25%5%6%8%55%
2131
21st to endDay
2313435%6%7%9%56%
2219
May1st to 10thDay
44145%46%6%8%9%50%
2340
11th to 20thDay
43144246%7%10%55%
2301
21st to endDay
3323435%6%7%9%56%
2707
June1st to 10thDay
221232445%8%68%
2520
11th to 20thDay
2212323347%72%
2520
21st to endDay
111232336%8%71%
2520
July1st to 10thDay
221333447%8%61%
2473
11th to 20thDay
2213435%5%9%11%57%
2340
21st to endDay
3312436%6%8%14%50%
2545
August1st to 10thDay
33245%35%6%8%8%53%
2328
11th to 20thDay
31123245%5%8%64%
2299
21st to endDay
32124335%6%9%62%
2381
September1st to 10thDay
421332345%7%67%
2160
11th to 20thDay
221332445%7%67%
2074
21st to endDay
3213323345%71%
1941
October1st to 10thDay
6%323324346%64%
1800
11th to 20thDay
2212323347%72%
1800
21st to endDay
342332335%6%66%
1980
November1st to 10thDay
231232445%7%67%
1859
11th to 20thDay
321342445%7%65%
1598
21st to endDay
3424433448%62%
1520
December1st to 10thDay
36%36%435%5%6%7%52%
1520
11th to 20thDay
35%46%6%45%5%6%8%50%
1926
21st to endDay
37%36%435%5%5%8%51%
2794
January1st to 10thNight
26%25%5%35%6%7%9%50%
2495
11th to 20thNight
25%35%6%3445%8%56%
2405
21st to endNight
37%25%5%45%5%5%9%49%
2574
February1st to 10thNight
15%36%5%35%5%6%9%54%
2340
11th to 20thNight
37%35%436%5%6%9%49%
2272
21st to endNight
37%25%6%45%5%6%6%51%
1757
March1st to 10thNight
35%345%45%6%6%7%54%
1980
11th to 20thNight
35%25%425%45%7%58%
1980
21st to endNight
46%35%5%47%6%6%8%47%
2178
April1st to 10thNight
44246%46%6%5%8%52%
1835
11th to 20thNight
5%5%245%445%5%9%52%
1777
21st to endNight
44344346%8%10%51%
1738
May1st to 10thNight
6%423445%5%7%10%50%
1620
11th to 20thNight
33145%35%5%5%9%56%
1594
21st to endNight
4313426%5%6%8%57%
1565
June1st to 10thNight
121242345%9%66%
1440
11th to 20thNight
331241345%6%67%
1440
21st to endNight
12232435%9%70%
1440
July1st to 10thNight
3113435%5%6%10%59%
1482
11th to 20thNight
22125%25%6%8%13%54%
1620
21st to endNight
3314436%8%9%12%47%
1773
August1st to 10thNight
3313435%5%9%9%55%
1611
11th to 20thNight
331432445%9%62%
1602
21st to endNight
22134345%5%9%60%
1973
September1st to 10thNight
321343346%6%66%
1800
11th to 20thNight
222332445%7%66%
1882
21st to endNight
321222344472%
2017
October1st to 10thNight
5%31332345%6%64%
2160
11th to 20thNight
3212314345%70%
2160
21st to endNight
44135%22346%65%
2376
November1st to 10thNight
2323324446%67%
2220
11th to 20thNight
2314323447%68%
2560
21st to endNight
45%2442435%7%60%
2660
December1st to 10thNight
35%36%5%44446%56%
2660
11th to 20thNight
36%245%45%7%7%9%48%
3271
21st to endNight
47%36%6%3446%8%48%
4873

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
28%14%23%28%6%1
1685
11th to 20thDay
25%9%23%32%10%1
1665
21st to endDay
30%9%22%27%10%2
1782
February1st to 10thDay
29%9%21%26%13%2
1620
11th to 20thDay
32%7%17%26%16%2
1584
21st to endDay
30%10%11%28%18%4
1494
March1st to 10thDay
29%8%13%27%21%3
1980
11th to 20thDay
25%7%14%32%16%6%
1980
21st to endDay
28%8%13%28%18%5%
2178
April1st to 10thDay
25%8%11%24%21%11%
2124
11th to 20thDay
25%7%11%24%25%8%
2134
21st to endDay
20%7%12%26%28%8%
2219
May1st to 10thDay
26%9%11%20%26%9%
2340
11th to 20thDay
21%8%12%23%25%11%
2304
21st to endDay
20%8%11%18%30%13%
2707
June1st to 10thDay
14%47%18%32%25%
2520
11th to 20thDay
14%46%10%23%42%
2520
21st to endDay
11%45%12%26%42%
2520
July1st to 10thDay
18%6%9%13%18%36%
2406
11th to 20thDay
18%6%12%20%21%23%
2271
21st to endDay
22%9%15%21%18%15%
2404
August1st to 10thDay
24%8%13%18%16%20%
2313
11th to 20thDay
17%5%10%19%23%27%
2299
21st to endDay
19%6%8%21%25%21%
2381
September1st to 10thDay
17%5%8%15%23%33%
2160
11th to 20thDay
16%7%9%19%24%25%
2074
21st to endDay
17%46%14%39%21%
1941
October1st to 10thDay
21%6%10%24%27%13%
1800
11th to 20thDay
13%48%25%37%13%
1800
21st to endDay
19%5%10%32%27%6%
1980
November1st to 10thDay
16%6%12%27%32%7%
1859
11th to 20thDay
21%6%12%35%23%3
1598
21st to endDay
22%6%15%32%23%3
1520
December1st to 10thDay
28%9%23%25%12%2
1520
11th to 20thDay
31%11%19%32%7%
1924
21st to endDay
30%9%20%22%18%1
2794
January1st to 10thNight
28%12%22%28%9%1
2495
11th to 20thNight
26%10%21%31%10%1
2405
21st to endNight
30%9%20%28%11%2
2574
February1st to 10thNight
26%10%21%29%12%2
2340
11th to 20thNight
31%10%15%25%17%2
2273
21st to endNight
28%10%13%28%17%3
1757
March1st to 10thNight
26%9%13%27%23%2
1980
11th to 20thNight
24%7%10%28%24%7%
1980
21st to endNight
31%10%12%25%18%4
2178
April1st to 10thNight
29%8%10%21%22%11%
1835
11th to 20thNight
28%8%12%19%23%10%
1777
21st to endNight
25%9%12%21%25%8%
1738
May1st to 10thNight
27%8%13%17%25%9%
1620
11th to 20thNight
22%9%12%20%28%9%
1595
21st to endNight
21%9%9%18%30%13%
1565
June1st to 10thNight
14%5%10%16%29%25%
1440
11th to 20thNight
18%5%8%11%18%40%
1440
21st to endNight
12%46%12%23%43%
1440
July1st to 10thNight
20%6%9%13%18%34%
1440
11th to 20thNight
18%8%11%19%19%25%
1566
21st to endNight
24%9%16%21%15%14%
1674
August1st to 10thNight
22%8%12%21%18%19%
1602
11th to 20thNight
19%5%11%18%19%28%
1602
21st to endNight
19%7%10%17%20%27%
1973
September1st to 10thNight
18%5%8%14%18%37%
1800
11th to 20thNight
17%5%10%20%20%28%
1882
21st to endNight
15%6%6%15%32%27%
2017
October1st to 10thNight
21%6%9%20%27%17%
2160
11th to 20thNight
15%5%8%19%36%17%
2160
21st to endNight
20%6%7%29%29%8%
2376
November1st to 10thNight
16%7%11%26%31%10%
2220
11th to 20thNight
17%6%12%33%29%4
2560
21st to endNight
24%7%10%28%25%5%
2660
December1st to 10thNight
29%7%18%25%17%2
2660
11th to 20thNight
29%12%19%30%9%1
3272
21st to endNight
31%12%16%23%17%1
4873

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
7%425%34%22%8%
270
11th to 20thDay
6%5%22%42%20%5%
255
21st to endDay
6%316%42%25%9%
264
February1st to 10thDay
45%23%48%16%4
240
11th to 20thDay
8%5%24%45%16%2
240
21st to endDay
7%11%24%43%12%4
246
March1st to 10thDay
8%13%30%30%16%3
420
11th to 20thDay
7%11%26%33%18%4
420
21st to endDay
8%15%36%29%11%1
462
April1st to 10thDay
5%18%30%27%16%4
420
11th to 20thDay
10%18%32%27%10%3
412
21st to endDay
6%18%28%28%16%5%
420
May1st to 10thDay
5%13%37%26%16%3
423
11th to 20thDay
49%25%34%20%7%
448
21st to endDay
410%24%29%27%6%
662
June1st to 10thDay
36%21%32%32%7%
630
11th to 20thDay
37%24%33%27%6%
630
21st to endDay
25%19%37%32%5%
630
July1st to 10thDay
2212%30%42%12%
576
11th to 20thDay
2112%33%38%15%
444
21st to endDay
217%32%40%17%
487
August1st to 10thDay
3215%34%36%10%
447
11th to 20thDay
3311%31%36%15%
437
21st to endDay
3114%31%40%11%
495
September1st to 10thDay
4416%28%32%17%
450
11th to 20thDay
26%20%34%29%10%
450
21st to endDay
48%18%27%33%11%
411
October1st to 10thDay
7%8%16%24%30%14%
270
11th to 20thDay
28%16%29%35%10%
270
21st to endDay
6%7%16%35%30%7%
297
November1st to 10thDay
48%21%36%25%6%
270
11th to 20thDay
2422%42%22%8%
270
21st to endDay
45%21%37%25%9%
270
December1st to 10thDay
7%320%43%17%9%
270
11th to 20thDay
5%422%41%23%6%
270
21st to endDay
8%7%21%43%16%5%
297
January1st to 10thNight
5%317%47%23%4
798
11th to 20thNight
5%221%44%23%4
740
21st to endNight
6%317%51%19%4
792
February1st to 10thNight
3222%53%17%3
720
11th to 20thNight
6%324%50%16%2
704
21st to endNight
6%425%54%11%1
592
March1st to 10thNight
5%5%25%47%17%1
720
11th to 20thNight
7%220%49%21%2
720
21st to endNight
5%6%22%52%15%1
792
April1st to 10thNight
6%7%29%43%14%
575
11th to 20thNight
7%8%23%47%14%1
533
21st to endNight
5%7%27%38%21%3
540
May1st to 10thNight
8%324%46%17%1
540
11th to 20thNight
4418%45%27%3
531
21st to endNight
6%7%20%38%28%2
584
June1st to 10thNight
1318%46%29%2
540
11th to 20thNight
4320%47%23%2
540
21st to endNight
2111%49%36%1
540
July1st to 10thNight
2110%39%44%3
525
11th to 20thNight
26%37%50%5%
522
21st to endNight
35%33%55%5%
591
August1st to 10thNight
417%37%49%2
537
11th to 20thNight
417%41%44%3
534
21st to endNight
318%40%44%5%
594
September1st to 10thNight
4110%42%40%4
540
11th to 20thNight
219%48%38%3
622
21st to endNight
4215%34%38%7%
720
October1st to 10thNight
7%415%43%28%3
720
11th to 20thNight
4216%44%31%3
720
21st to endNight
7%417%40%29%3
792
November1st to 10thNight
3417%46%28%2
740
11th to 20thNight
3220%52%20%4
912
21st to endNight
6%420%42%25%3
950
December1st to 10thNight
6%316%54%19%2
950
11th to 20thNight
7%422%45%21%2
950
21st to endNight
7%5%21%51%14%2
1045
Page generated at 2024-01-12 23:38:10. Version ac07

Copyright 2024 Attilla Danko


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