Black Canyon of the Gunnison
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Black Canyon of the Gunnison clear sky chart from 2005-11-06 to 2024-03-23.

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
55%
24691
23%
80291
20%
24601
61%
24601
31%
47548

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
48%
844
17%
4202
16%
831
54%
831
16%
2740
January11th to 20thNight
49%
754
17%
4082
20%
740
55%
740
15%
2694
January21st to endNight
47%
830
16%
4395
22%
814
53%
814
16%
2664
February1st to 10thNight
42%
760
19%
2470
16%
760
49%
760
25%
1575
February11th to 20thNight
43%
740
19%
2370
16%
740
49%
740
25%
1508
February21st to endNight
39%
628
26%
1884
17%
628
50%
628
26%
1233
March1st to 10thNight
44%
760
24%
2100
15%
760
52%
760
29%
1367
March11th to 20thNight
53%
760
26%
2090
19%
760
57%
760
34%
1298
March21st to endNight
45%
792
20%
2192
14%
792
50%
792
26%
1487
April1st to 10thNight
42%
540
21%
1800
18%
540
48%
540
23%
1129
April11th to 20thNight
45%
533
21%
1777
18%
533
52%
533
23%
1127
April21st to endNight
46%
540
23%
1800
17%
540
55%
540
28%
1061
May1st to 10thNight
47%
540
22%
1652
18%
540
52%
540
29%
990
May11th to 20thNight
56%
531
23%
1542
20%
531
61%
531
34%
920
May21st to endNight
52%
582
24%
1552
15%
582
59%
582
38%
924
June1st to 10thNight
63%
540
31%
1440
23%
540
69%
540
49%
781
June11th to 20thNight
63%
540
32%
1440
23%
540
69%
540
54%
747
June21st to endNight
71%
540
30%
1440
24%
540
75%
540
54%
737
July1st to 10thNight
74%
525
24%
1400
21%
525
76%
525
45%
781
July11th to 20thNight
77%
522
22%
1539
20%
522
78%
522
42%
856
July21st to endNight
76%
591
16%
1674
14%
558
77%
558
32%
1012
August1st to 10thNight
71%
537
18%
1602
17%
534
72%
534
35%
918
August11th to 20thNight
76%
534
29%
1660
27%
534
78%
534
44%
848
August21st to endNight
71%
594
28%
1980
31%
594
72%
594
37%
1074
September1st to 10thNight
73%
540
31%
1800
33%
540
78%
540
40%
933
September11th to 20thNight
70%
543
34%
1803
34%
543
74%
543
41%
910
September21st to endNight
68%
720
34%
2062
26%
720
73%
720
51%
1053
October1st to 10thNight
62%
720
29%
2160
22%
720
67%
720
42%
1170
October11th to 20thNight
65%
720
35%
2160
25%
720
71%
720
48%
1084
October21st to endNight
62%
792
34%
2376
25%
792
67%
792
42%
1286
November1st to 10thNight
61%
763
33%
2243
24%
763
67%
763
45%
1188
November11th to 20thNight
56%
950
31%
2508
20%
950
62%
950
44%
1426
November21st to endNight
54%
950
27%
2660
19%
950
60%
950
38%
1572
December1st to 10thNight
50%
950
19%
2660
14%
950
53%
950
33%
1662
December11th to 20thNight
41%
950
20%
3115
12%
949
46%
949
22%
2018
December21st to endNight
37%
1036
11%
4661
10%
1026
42%
1026
16%
2775

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
6%8%35%5%345%5%7%50%
78884
Night
6%9%35%42445%6%51%
81066
TransparencyDay
32%8%9%21%21%9%
78602
Night
33%7%10%22%21%7%
80869
SeeingDay
9%12%28%32%16%2
14423
Night
10%6%22%41%20%2
24729

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
49%411%7%446%6%6%37%
2727
11th to 20thDay
7%17%49%6%2447%5%36%
2860
21st to endDay
5%12%5%7%423346%48%
3146
February1st to 10thDay
8%12%48%6%3435%6%41%
1710
11th to 20thDay
7%14%5%7%5%2445%6%41%
1697
21st to endDay
5%15%6%9%6%34345%40%
1570
March1st to 10thDay
7%13%47%42345%7%43%
2076
11th to 20thDay
5%10%5%5%43446%7%47%
2090
21st to endDay
5%14%5%7%5%35%45%7%40%
2209
April1st to 10thDay
8%11%46%4245%47%45%
2160
11th to 20thDay
8%12%46%5%35%45%7%41%
2131
21st to endDay
6%9%35%435%5%6%8%45%
2160
May1st to 10thDay
7%10%35%5%446%6%7%43%
2305
11th to 20thDay
6%6%25%5%37%6%7%8%46%
2349
21st to endDay
6%6%245%345%6%7%52%
2724
June1st to 10thDay
332333446%9%60%
2520
11th to 20thDay
432432445%6%64%
2520
21st to endDay
2214425%5%5%7%63%
2520
July1st to 10thDay
3325%436%6%6%8%54%
2520
11th to 20thDay
33245%36%7%8%9%50%
2365
21st to endDay
5%5%35%6%48%8%9%10%39%
2545
August1st to 10thDay
6%425%6%5%6%8%8%10%42%
2328
11th to 20thDay
4314435%6%6%8%55%
2241
21st to endDay
4325%6%35%7%6%8%51%
2376
September1st to 10thDay
6%324425%5%6%6%57%
2160
11th to 20thDay
5%4134245%5%7%60%
2154
21st to endDay
6%314423346%64%
1896
October1st to 10thDay
8%5%2343345%6%58%
1800
11th to 20thDay
6%423322345%67%
1800
21st to endDay
7%7%33322345%60%
1980
November1st to 10thDay
46%2332335%6%64%
1815
11th to 20thDay
8%7%3432334460%
1670
21st to endDay
5%10%37%41334457%
1520
December1st to 10thDay
9%12%46%42333450%
1520
11th to 20thDay
8%12%48%5%34446%43%
1926
21st to endDay
5%12%47%6%3445%6%44%
2794
January1st to 10thNight
413%9%10%5%34445%40%
4257
11th to 20thNight
7%21%6%6%5%23346%37%
4110
21st to endNight
5%16%5%8%5%23345%44%
4521
February1st to 10thNight
7%15%47%5%23446%45%
2470
11th to 20thNight
7%12%48%5%2446%5%44%
2369
21st to endNight
5%15%46%434445%44%
1884
March1st to 10thNight
8%11%45%5%3445%5%47%
2100
11th to 20thNight
410%46%434445%51%
2090
21st to endNight
8%15%46%5%3446%5%41%
2192
April1st to 10thNight
9%13%46%6%33446%44%
1800
11th to 20thNight
7%11%47%5%3345%6%44%
1777
21st to endNight
11%8%35%43445%6%48%
1800
May1st to 10thNight
10%7%25%435%47%7%46%
1652
11th to 20thNight
8%5%26%4245%46%53%
1541
21st to endNight
8%425%4245%5%8%54%
1552
June1st to 10thNight
3323425%5%5%7%61%
1440
11th to 20thNight
4213422445%67%
1440
21st to endNight
32124335%7%7%64%
1440
July1st to 10thNight
42135%35%6%7%9%56%
1440
11th to 20thNight
23245%35%6%8%11%52%
1591
21st to endNight
3325%6%47%7%9%13%41%
1773
August1st to 10thNight
5%425%435%6%7%9%50%
1611
11th to 20thNight
5%4233245%7%9%57%
1660
21st to endNight
44246%346%6%8%53%
1980
September1st to 10thNight
4425%4345%6%7%58%
1800
11th to 20thNight
5%4145%235%5%7%60%
1803
21st to endNight
6%323322335%68%
2062
October1st to 10thNight
8%5%2342335%6%59%
2160
11th to 20thNight
6%413322236%68%
2160
21st to endNight
9%7%23222235%62%
2376
November1st to 10thNight
5%5%23423346%63%
2243
11th to 20thNight
8%7%23312345%61%
2508
21st to endNight
7%9%44322446%55%
2660
December1st to 10thNight
9%11%35%323345%51%
2660
11th to 20thNight
7%13%47%5%2346%8%41%
3271
21st to endNight
5%13%6%7%5%33346%45%
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
40%13%13%21%12%1
2728
11th to 20thDay
44%11%16%19%9%1
2860
21st to endDay
36%9%11%31%10%2
3146
February1st to 10thDay
45%8%13%19%12%3
1710
11th to 20thDay
43%7%7%24%17%3
1706
21st to endDay
46%7%421%18%3
1570
March1st to 10thDay
41%7%7%24%19%3
2076
11th to 20thDay
35%7%9%31%14%3
2090
21st to endDay
43%8%6%25%15%3
2209
April1st to 10thDay
38%7%7%22%19%7%
2160
11th to 20thDay
41%7%7%21%20%4
2134
21st to endDay
35%8%7%25%22%3
2160
May1st to 10thDay
37%9%7%21%21%5%
2305
11th to 20thDay
34%8%9%24%21%4
2352
21st to endDay
30%7%8%18%27%9%
2724
June1st to 10thDay
21%6%5%22%29%16%
2520
11th to 20thDay
21%5%5%12%28%29%
2520
21st to endDay
18%6%416%26%29%
2520
July1st to 10thDay
26%8%7%14%20%25%
2451
11th to 20thDay
26%10%13%19%19%14%
2294
21st to endDay
34%11%17%19%13%6%
2404
August1st to 10thDay
33%11%12%17%16%12%
2313
11th to 20thDay
25%8%8%17%27%14%
2241
21st to endDay
28%8%9%20%22%12%
2376
September1st to 10thDay
26%7%7%13%27%19%
2160
11th to 20thDay
23%7%8%18%28%15%
2154
21st to endDay
22%5%418%39%11%
1896
October1st to 10thDay
27%6%7%26%25%9%
1800
11th to 20thDay
21%4427%35%9%
1800
21st to endDay
27%6%8%30%25%5%
1980
November1st to 10thDay
23%6%8%26%33%4
1815
11th to 20thDay
29%5%8%32%23%3
1670
21st to endDay
32%5%9%27%23%4
1520
December1st to 10thDay
40%5%15%22%15%3
1520
11th to 20thDay
43%6%8%26%17%1
1924
21st to endDay
38%10%10%16%22%4
2794
January1st to 10thNight
45%9%10%21%14%1
4257
11th to 20thNight
45%10%15%20%9%1
4110
21st to endNight
42%8%13%25%11%2
4521
February1st to 10thNight
42%6%14%21%16%2
2470
11th to 20thNight
40%7%9%25%17%2
2370
21st to endNight
42%6%5%24%20%3
1884
March1st to 10thNight
38%7%6%24%22%3
2100
11th to 20thNight
34%7%6%30%20%4
2090
21st to endNight
43%6%7%24%17%2
2192
April1st to 10thNight
41%6%6%20%21%6%
1800
11th to 20thNight
41%7%6%18%22%6%
1777
21st to endNight
36%6%8%23%24%3
1800
May1st to 10thNight
34%7%9%21%23%6%
1652
11th to 20thNight
30%9%11%23%22%4
1542
21st to endNight
27%8%9%18%28%11%
1552
June1st to 10thNight
20%7%6%18%30%18%
1440
11th to 20thNight
19%46%15%21%35%
1440
21st to endNight
16%6%5%16%24%31%
1440
July1st to 10thNight
22%8%11%13%22%24%
1400
11th to 20thNight
23%9%15%22%14%18%
1539
21st to endNight
29%12%22%18%12%7%
1674
August1st to 10thNight
26%10%17%18%15%13%
1602
11th to 20thNight
23%6%15%17%21%20%
1660
21st to endNight
26%8%12%18%22%15%
1980
September1st to 10thNight
24%7%8%16%23%23%
1800
11th to 20thNight
23%6%10%16%26%18%
1803
21st to endNight
21%4420%39%13%
2062
October1st to 10thNight
26%5%7%25%26%12%
2160
11th to 20thNight
21%5%6%23%33%12%
2160
21st to endNight
26%5%7%29%28%5%
2376
November1st to 10thNight
24%5%8%28%29%6%
2243
11th to 20thNight
27%49%31%25%4
2508
21st to endNight
31%5%6%26%27%4
2660
December1st to 10thNight
36%5%14%24%18%2
2660
11th to 20thNight
41%6%9%23%20%1
3272
21st to endNight
40%7%9%17%24%2
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
16%8%31%31%13%1
270
11th to 20thDay
12%16%35%27%10%
270
21st to endDay
10%7%32%37%13%1
297
February1st to 10thDay
13%17%36%27%5%2
270
11th to 20thDay
18%14%38%24%5%1
270
21st to endDay
13%20%38%23%5%1
225
March1st to 10thDay
16%20%29%25%9%1
446
11th to 20thDay
12%18%28%29%13%
460
21st to endDay
17%23%33%20%6%
471
April1st to 10thDay
14%20%31%22%11%1
420
11th to 20thDay
17%23%32%18%8%1
412
21st to endDay
16%21%32%21%9%1
420
May1st to 10thDay
14%19%33%26%9%
423
11th to 20thDay
9%13%31%28%16%3
496
21st to endDay
10%15%27%31%15%2
679
June1st to 10thDay
5%10%28%33%21%1
630
11th to 20thDay
7%11%33%31%17%1
630
21st to endDay
312%27%41%17%1
630
July1st to 10thDay
36%17%48%23%3
621
11th to 20thDay
4416%43%28%4
467
21st to endDay
6%415%40%31%5%
487
August1st to 10thDay
5%8%22%42%19%4
447
11th to 20thDay
5%5%22%40%25%3
437
21st to endDay
4320%46%25%2
495
September1st to 10thDay
6%6%26%36%23%2
450
11th to 20thDay
6%6%32%40%13%2
450
21st to endDay
8%11%26%33%21%1
366
October1st to 10thDay
10%13%23%30%22%3
270
11th to 20thDay
5%15%28%31%19%2
270
21st to endDay
10%12%28%33%16%1
297
November1st to 10thDay
9%17%29%30%14%1
270
11th to 20thDay
7%11%34%32%14%2
270
21st to endDay
12%11%31%29%14%2
270
December1st to 10thDay
10%14%35%29%10%1
270
11th to 20thDay
12%10%32%31%13%1
270
21st to endDay
13%13%37%26%10%1
297
January1st to 10thNight
13%7%23%40%16%1
855
11th to 20thNight
12%9%22%41%14%1
760
21st to endNight
12%7%24%43%12%1
836
February1st to 10thNight
13%9%28%40%9%
760
11th to 20thNight
11%8%28%42%11%
744
21st to endNight
14%7%32%39%7%
628
March1st to 10thNight
13%9%28%39%11%1
760
11th to 20thNight
7%8%25%42%18%
760
21st to endNight
16%8%25%39%12%
792
April1st to 10thNight
13%11%27%39%10%
540
11th to 20thNight
14%10%24%38%13%2
533
21st to endNight
14%8%25%36%16%1
540
May1st to 10thNight
13%6%27%39%14%1
540
11th to 20thNight
10%423%40%20%3
531
21st to endNight
8%8%26%35%21%3
584
June1st to 10thNight
35%23%41%27%2
540
11th to 20thNight
5%423%46%21%2
540
21st to endNight
4317%45%29%2
540
July1st to 10thNight
5%211%46%35%2
525
11th to 20thNight
3110%40%42%4
522
21st to endNight
428%42%42%3
591
August1st to 10thNight
6%211%39%39%3
537
11th to 20thNight
4310%44%35%3
534
21st to endNight
6%211%42%35%4
594
September1st to 10thNight
4413%49%30%1
540
11th to 20thNight
6%215%45%30%2
543
21st to endNight
7%417%42%27%4
720
October1st to 10thNight
9%420%45%21%1
720
11th to 20thNight
6%6%19%45%22%3
720
21st to endNight
12%418%42%21%3
792
November1st to 10thNight
7%5%22%44%19%2
763
11th to 20thNight
11%6%22%42%18%2
950
21st to endNight
11%8%23%42%16%1
950
December1st to 10thNight
13%7%23%44%12%1
950
11th to 20thNight
15%9%25%37%13%
950
21st to endNight
13%9%28%41%8%
1045
Page generated at 2024-03-19 21:31:07. Version ac07

Copyright © 2024 Attilla Danko.


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