Durango
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Durango clear sky chart from 2005-11-05 to

2017-09-12
.

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
61%
15746
28%
46885
22%
15706
68%
15706
41%
25635

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 15thNight
58%
717
30%
2327
25%
716
67%
716
43%
1170
January16th to endNight
56%
768
32%
2496
27%
768
65%
768
40%
1287
February1st to 15thNight
56%
701
26%
2288
22%
699
65%
699
41%
1177
February16th to endNight
50%
632
34%
1908
21%
632
64%
632
39%
1047
March1st to 15thNight
57%
720
32%
1980
21%
720
65%
720
45%
1081
March16th to endNight
52%
768
28%
2112
17%
768
60%
768
42%
1190
April1st to 15thNight
47%
542
25%
1801
16%
542
59%
542
33%
984
April16th to endNight
50%
540
31%
1800
23%
540
64%
540
39%
912
May1st to 15thNight
55%
539
25%
1663
20%
539
62%
539
38%
911
May16th to endNight
55%
562
27%
1585
18%
561
62%
561
40%
890
June1st to 15thNight
68%
540
31%
1440
23%
540
72%
540
57%
727
June16th to endNight
78%
540
29%
1440
24%
540
80%
540
56%
734
July1st to 15thNight
71%
510
13%
1477
12%
510
71%
510
26%
959
July16th to endNight
76%
564
15%
1593
14%
531
77%
531
24%
1069
August1st to 15thNight
76%
539
19%
1611
19%
536
76%
536
31%
995
August16th to endNight
76%
573
23%
1902
25%
573
77%
573
34%
1085
September1st to 15thNight
70%
530
23%
1766
24%
530
73%
530
30%
1038
September16th to endNight
75%
615
35%
1818
29%
615
79%
615
50%
919
October1st to 15thNight
63%
660
33%
1980
24%
660
69%
660
45%
1030
October16th to endNight
70%
704
38%
2112
27%
704
78%
704
53%
1012
November1st to 15thNight
70%
727
37%
2127
29%
727
75%
727
53%
1042
November16th to endNight
61%
900
36%
2456
24%
900
69%
900
51%
1279
December1st to 15thNight
52%
900
25%
2520
16%
900
60%
900
42%
1410
December16th to endNight
49%
955
22%
2683
16%
955
54%
955
32%
1687

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
5%5%1442445%6%54%
47762
Night
5%413323446%58%
47081
TransparencyDay
27%6%10%21%23%10%
47457
Night
26%410%22%24%11%
46887
SeeingDay
9%11%28%31%15%3
5560
Night
8%320%38%25%3
15754

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 15thDay
5%6%14313346%59%
1611
16th to endDay
5%8%23313335%59%
1728
February1st to 15thDay
38%24423345%58%
1575
16th to endDay
5%8%34424445%50%
1563
March1st to 15thDay
36%2332445%6%56%
1980
16th to endDay
5%5%24435%446%53%
2112
April1st to 15thDay
5%6%145%2445%8%51%
2145
16th to endDay
45%1443445%7%53%
2160
May1st to 15thDay
5%5%244345%5%7%51%
2285
16th to endDay
5%4133245%5%7%55%
2526
June1st to 15thDay
3212324445%64%
2520
16th to endDay
112224446%67%
2520
July1st to 15thDay
4325%5%46%7%8%9%42%
2389
16th to endDay
6%426%7%48%8%8%10%31%
2467
August1st to 15thDay
6%425%7%47%6%7%8%38%
2340
16th to endDay
6%415%447%7%7%9%41%
2298
September1st to 15thDay
9%415%5%36%46%7%44%
2113
16th to endDay
6%213323245%63%
1809
October1st to 15thDay
8%412313337%58%
1650
16th to endDay
431232222468%
1760
November1st to 15thDay
432223245%68%
1717
16th to endDay
45%211333468%
1503
December1st to 15thDay
7%7%22123345%58%
1440
16th to endDay
7%10%35%423246%48%
1551
January1st to 15thNight
46%1322223464%
2327
16th to endNight
6%6%22213345%62%
2496
February1st to 15thNight
47%23212337%61%
2277
16th to endNight
47%2331333362%
1908
March1st to 15thNight
45%23323347%61%
1980
16th to endNight
6%41332335%6%58%
2112
April1st to 15thNight
7%42342445%6%54%
1801
16th to endNight
6%413223336%62%
1800
May1st to 15thNight
6%5%14324346%56%
1663
16th to endNight
8%5%12333347%56%
1585
June1st to 15thNight
2312212337%68%
1440
16th to endNight
11232445%8%65%
1440
July1st to 15thNight
4325%7%36%8%7%10%40%
1567
16th to endNight
44346%48%9%8%9%35%
1701
August1st to 15thNight
6%424435%6%8%7%45%
1620
16th to endNight
43235%35%6%6%10%48%
1902
September1st to 15thNight
7%3147%35%6%6%8%45%
1766
16th to endNight
6%21232233468%
1818
October1st to 15thNight
9%32212335%64%
1980
16th to endNight
421221233470%
2112
November1st to 15thNight
431213346%67%
2127
16th to endNight
5%412112225%68%
2456
December1st to 15thNight
6%7%13313345%61%
2520
16th to endNight
7%9%34323335%51%
2683

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 15thDay
27%414%33%17%1
1612
16th to endDay
28%5%11%27%22%5%
1728
February1st to 15thDay
29%6%14%27%16%6%
1575
16th to endDay
35%47%19%29%2
1563
March1st to 15thDay
26%47%30%26%4
1980
16th to endDay
29%5%7%25%26%5%
2112
April1st to 15thDay
31%5%7%22%24%9%
2145
16th to endDay
27%5%7%24%26%8%
2160
May1st to 15thDay
29%6%10%19%27%6%
2285
16th to endDay
25%6%9%16%30%11%
2529
June1st to 15thDay
19%46%14%27%27%
2520
16th to endDay
15%45%11%28%33%
2520
July1st to 15thDay
31%10%14%13%14%16%
2250
16th to endDay
38%12%16%18%10%3
2312
August1st to 15thDay
36%9%12%14%15%10%
2325
16th to endDay
31%10%12%19%18%8%
2298
September1st to 15thDay
33%8%11%16%18%10%
2113
16th to endDay
21%5%7%15%35%15%
1809
October1st to 15thDay
24%5%6%23%29%10%
1650
16th to endDay
20%36%22%36%10%
1760
November1st to 15thDay
19%38%27%32%8%
1717
16th to endDay
20%36%31%29%9%
1503
December1st to 15thDay
28%6%15%30%16%2
1440
16th to endDay
39%6%16%21%14%1
1551
January1st to 15thNight
24%311%31%25%2
2327
16th to endNight
26%49%30%25%4
2496
February1st to 15thNight
26%315%28%18%7%
2288
16th to endNight
27%47%20%33%6%
1908
March1st to 15thNight
25%36%29%28%6%
1980
16th to endNight
26%48%22%28%10%
2112
April1st to 15thNight
30%47%18%26%12%
1801
16th to endNight
24%35%23%29%13%
1800
May1st to 15thNight
28%49%18%30%8%
1664
16th to endNight
26%5%9%17%26%13%
1586
June1st to 15thNight
17%37%12%25%34%
1440
16th to endNight
16%47%10%22%38%
1440
July1st to 15thNight
36%11%13%10%8%19%
1477
16th to endNight
38%12%17%16%9%6%
1593
August1st to 15thNight
32%10%15%13%14%13%
1611
16th to endNight
29%7%16%20%16%8%
1902
September1st to 15thNight
33%6%13%16%14%15%
1766
16th to endNight
21%36%15%32%21%
1818
October1st to 15thNight
24%37%20%26%17%
1980
16th to endNight
18%36%18%38%14%
2112
November1st to 15thNight
18%46%26%32%11%
2127
16th to endNight
21%26%27%32%9%
2456
December1st to 15thNight
26%415%28%20%4
2520
16th to endNight
37%414%24%16%2
2683

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 15thDay
27%13%21%25%11%1
90
16th to endDay
13%10%32%27%13%3
96
February1st to 15thDay
11%10%28%37%11%1
90
16th to endDay
15%18%33%24%8%
93
March1st to 15thDay
15%19%33%21%9%
270
16th to endDay
13%29%33%16%6%
288
April1st to 15thDay
15%27%32%17%42
269
16th to endDay
20%31%32%13%3
270
May1st to 15thDay
10%23%41%18%6%
288
16th to endDay
7%17%31%26%14%3
427
June1st to 15thDay
5%7%27%33%22%3
495
16th to endDay
2322%37%26%7%
495
July1st to 15thDay
45%24%35%23%6%
354
16th to endDay
6%20%44%20%6%
327
August1st to 15thDay
9%121%46%16%4
315
16th to endDay
7%325%40%19%4
332
September1st to 15thDay
9%331%40%13%3
300
16th to endDay
8%6%30%39%9%6%
209
October1st to 15thDay
5%8%28%26%24%5%
90
16th to endDay
7%8%30%30%20%3
96
November1st to 15thDay
12%10%16%28%28%3
90
16th to endDay
20%11%35%23%10%
90
December1st to 15thDay
11%14%37%33%3
90
16th to endDay
19%14%25%31%8%1
96
January1st to 15thNight
8%223%41%18%5%
720
16th to endNight
11%323%37%18%4
768
February1st to 15thNight
9%325%43%15%1
704
16th to endNight
9%6%30%43%10%
632
March1st to 15thNight
6%426%38%20%1
720
16th to endNight
9%6%27%36%18%1
768
April1st to 15thNight
9%10%29%37%13%
542
16th to endNight
8%10%26%38%15%1
540
May1st to 15thNight
7%5%25%41%18%1
540
16th to endNight
11%424%34%22%2
563
June1st to 15thNight
4220%41%29%1
540
16th to endNight
1213%43%36%2
540
July1st to 15thNight
311%34%44%5%
510
16th to endNight
5%15%30%48%9%
564
August1st to 15thNight
5%16%28%50%7%
539
16th to endNight
5%8%30%46%8%
573
September1st to 15thNight
8%8%39%38%4
530
16th to endNight
7%111%36%34%7%
615
October1st to 15thNight
10%220%38%23%5%
660
16th to endNight
5%217%40%28%6%
704
November1st to 15thNight
6%318%40%27%4
727
16th to endNight
9%5%21%36%22%5%
900
December1st to 15thNight
10%5%26%42%13%2
900
16th to endNight
13%425%38%15%2
955
Page generated at 2017-09-13 05:39:10. Version ac04

Copyright 2017 A. Danko


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