Coyote Howl Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coyote Howl Observatory clear sky chart from 2005-11-06 to 2024-01-22.

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
38%
24364
18%
74718
12%
24311
45%
24311
22%
50931

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
20%
950
13%
2648
5%
946
27%
946
13%
2072
January11th to 20thNight
15%
950
11%
2660
5%
950
21%
950
12%
2155
January21st to endNight
19%
896
12%
2695
5%
896
26%
896
13%
2078
February1st to 10thNight
19%
720
10%
2182
5%
720
23%
720
13%
1675
February11th to 20thNight
24%
700
14%
2098
7%
699
31%
699
17%
1514
February21st to endNight
19%
592
14%
1776
5%
592
28%
592
15%
1331
March1st to 10thNight
25%
720
16%
2160
8%
720
32%
720
18%
1491
March11th to 20thNight
28%
720
17%
2033
9%
720
35%
720
23%
1406
March21st to endNight
27%
740
15%
2126
7%
740
36%
740
19%
1535
April1st to 10thNight
31%
540
18%
1800
11%
540
42%
540
22%
1182
April11th to 20thNight
34%
533
20%
1775
15%
533
42%
533
23%
1142
April21st to endNight
27%
540
18%
1625
6%
540
38%
540
22%
1119
May1st to 10thNight
30%
540
13%
1620
7%
540
35%
540
18%
1177
May11th to 20thNight
45%
531
17%
1593
11%
531
50%
531
24%
1068
May21st to endNight
57%
583
17%
1717
11%
582
62%
582
31%
1068
June1st to 10thNight
57%
540
18%
1440
13%
540
60%
540
36%
899
June11th to 20thNight
58%
540
21%
1440
15%
540
62%
540
36%
887
June21st to endNight
61%
540
20%
1440
14%
540
66%
540
34%
899
July1st to 10thNight
68%
525
17%
1400
15%
525
70%
525
34%
897
July11th to 20thNight
71%
522
21%
1392
17%
522
73%
522
42%
820
July21st to endNight
68%
591
23%
1581
19%
558
70%
558
38%
942
August1st to 10thNight
69%
537
21%
1600
18%
534
71%
534
36%
922
August11th to 20thNight
69%
534
23%
1658
20%
534
71%
534
33%
978
August21st to endNight
70%
594
23%
1980
23%
594
74%
594
36%
1064
September1st to 10thNight
63%
566
23%
1826
21%
566
68%
566
31%
1081
September11th to 20thNight
67%
720
31%
1980
25%
720
70%
720
40%
1144
September21st to endNight
56%
720
27%
1980
20%
720
61%
720
35%
1203
October1st to 10thNight
54%
720
26%
1980
20%
720
60%
720
37%
1179
October11th to 20thNight
37%
720
23%
2114
15%
720
46%
720
27%
1354
October21st to endNight
30%
792
20%
2574
13%
792
40%
792
21%
1703
November1st to 10thNight
37%
740
25%
2406
18%
740
49%
740
28%
1423
November11th to 20thNight
32%
760
23%
2470
14%
760
44%
760
22%
1604
November21st to endNight
28%
760
18%
2470
11%
760
37%
760
16%
1778
December1st to 10thNight
22%
760
13%
2470
7%
760
30%
760
15%
1832
December11th to 20thNight
24%
893
14%
3149
7%
891
30%
891
14%
2295
December21st to endNight
17%
1035
7%
4860
5%
1026
23%
1026
6%
4014

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
15%9%46%5%35%5%5%7%36%
74948
Night
15%9%46%5%3445%6%38%
75005
TransparencyDay
47%6%11%21%13%2
74656
Night
47%5%10%21%14%2
74818
SeeingDay
17%8%25%25%17%8%
14425
Night
19%7%28%30%15%2
24378

By Month

Percentage Cloud Cover SE (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
18%14%5%10%7%45%45%5%23%
1517
11th to 20thDay
18%15%7%11%7%4444421%
1520
21st to endDay
16%17%8%10%6%35%45%6%21%
1693
February1st to 10thDay
20%13%7%9%7%4434425%
1774
11th to 20thDay
15%12%5%10%7%45%446%28%
1748
21st to endDay
18%14%6%8%5%24446%29%
1480
March1st to 10thDay
19%11%5%7%6%3445%7%31%
1800
11th to 20thDay
18%10%5%6%6%35%5%5%6%31%
1926
21st to endDay
22%12%47%7%34447%27%
2245
April1st to 10thDay
15%10%47%5%4445%6%35%
2160
11th to 20thDay
18%9%35%5%3446%6%37%
2134
21st to endDay
21%8%36%6%44446%35%
2335
May1st to 10thDay
19%9%46%6%45%5%5%6%32%
2340
11th to 20thDay
20%7%36%6%35%45%6%34%
2301
21st to endDay
11%5%36%6%46%5%7%10%36%
2555
June1st to 10thDay
11%6%36%6%45%5%6%8%41%
2520
11th to 20thDay
10%5%245%45%5%7%8%44%
2520
21st to endDay
10%5%26%5%35%6%6%9%43%
2520
July1st to 10thDay
11%425%6%46%6%7%10%39%
2520
11th to 20thDay
8%4245%35%6%8%10%46%
2520
21st to endDay
9%425%436%6%6%11%44%
2640
August1st to 10thDay
8%425%5%35%5%6%10%45%
2327
11th to 20thDay
11%5%25%5%35%6%9%10%39%
2240
21st to endDay
8%5%245%35%5%7%9%47%
2376
September1st to 10thDay
12%6%25%5%35%5%5%7%46%
2116
11th to 20thDay
11%5%245%345%6%8%46%
1980
21st to endDay
13%5%25%5%2445%6%49%
1980
October1st to 10thDay
13%5%26%5%3445%7%47%
1980
11th to 20thDay
15%5%245%25%5%5%7%43%
1843
21st to endDay
20%10%36%5%34447%34%
1782
November1st to 10thDay
9%6%345%3445%7%50%
1672
11th to 20thDay
15%11%5%6%5%3445%7%34%
1710
21st to endDay
20%11%47%433446%34%
1710
December1st to 10thDay
20%15%5%9%6%44346%25%
1710
11th to 20thDay
16%16%7%11%5%24445%27%
1971
21st to endDay
23%20%10%10%6%3333415%
2783
January1st to 10thNight
19%12%6%10%6%3445%5%26%
2648
11th to 20thNight
19%16%7%10%7%3433424%
2660
21st to endNight
17%14%6%10%7%45%445%26%
2695
February1st to 10thNight
21%13%5%8%7%34345%26%
2182
11th to 20thNight
16%11%5%10%5%3445%6%32%
2098
21st to endNight
19%12%5%9%5%34345%30%
1776
March1st to 10thNight
17%9%47%5%34446%37%
2160
11th to 20thNight
16%9%36%5%3445%6%38%
2033
21st to endNight
20%10%37%5%2445%7%32%
2126
April1st to 10thNight
15%8%35%436%5%5%7%39%
1800
11th to 20thNight
17%7%345%35%347%40%
1775
21st to endNight
18%8%36%5%345%6%6%35%
1625
May1st to 10thNight
19%9%47%6%35%45%8%30%
1620
11th to 20thNight
18%8%35%5%3446%8%39%
1592
21st to endNight
9%5%26%5%35%6%7%9%42%
1716
June1st to 10thNight
9%6%25%6%3446%7%49%
1440
11th to 20thNight
9%6%25%5%35%35%9%48%
1440
21st to endNight
7%325%6%45%7%8%10%45%
1440
July1st to 10thNight
9%4345%35%5%6%11%46%
1440
11th to 20thNight
8%3244345%6%8%53%
1440
21st to endNight
8%4346%335%5%8%51%
1674
August1st to 10thNight
8%424435%5%6%9%49%
1611
11th to 20thNight
7%425%445%46%7%50%
1658
21st to endNight
7%3245%3446%8%53%
1980
September1st to 10thNight
12%5%344335%5%8%48%
1826
11th to 20thNight
8%4245%2445%7%54%
1980
21st to endNight
11%5%24434446%52%
1980
October1st to 10thNight
10%5%24334446%54%
1980
11th to 20thNight
18%7%24433446%44%
2114
21st to endNight
19%7%36%6%3435%5%39%
2574
November1st to 10thNight
13%8%35%433445%49%
2406
11th to 20thNight
15%9%47%42435%7%40%
2470
21st to endNight
19%12%47%5%35%435%32%
2470
December1st to 10thNight
17%12%6%9%6%3445%6%28%
2470
11th to 20thNight
18%14%5%8%5%34445%30%
3222
21st to endNight
23%20%7%9%6%3434417%
4884

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
63%47%17%8%
1518
11th to 20thDay
67%5%10%13%5%
1520
21st to endDay
64%6%9%15%5%1
1693
February1st to 10thDay
64%39%14%9%1
1774
11th to 20thDay
59%49%19%8%1
1758
21st to endDay
58%49%20%8%2
1480
March1st to 10thDay
54%410%21%10%1
1800
11th to 20thDay
54%5%13%17%10%1
1926
21st to endDay
60%412%18%5%1
2245
April1st to 10thDay
49%6%12%20%13%1
2160
11th to 20thDay
47%412%23%11%3
2134
21st to endDay
51%5%11%20%10%3
2335
May1st to 10thDay
52%6%11%21%9%1
2340
11th to 20thDay
50%7%12%17%13%1
2305
21st to endDay
41%9%13%21%14%1
2555
June1st to 10thDay
40%7%12%23%15%3
2520
11th to 20thDay
35%8%11%25%19%2
2520
21st to endDay
37%8%16%20%15%4
2520
July1st to 10thDay
38%9%13%22%15%3
2451
11th to 20thDay
31%8%16%26%17%2
2445
21st to endDay
33%9%17%24%14%3
2493
August1st to 10thDay
33%7%14%31%14%2
2314
11th to 20thDay
37%8%14%25%15%1
2240
21st to endDay
32%8%12%25%16%7%
2376
September1st to 10thDay
38%6%12%23%18%4
2116
11th to 20thDay
34%6%12%25%20%3
1980
21st to endDay
35%5%10%25%24%1
1980
October1st to 10thDay
38%5%11%24%20%3
1980
11th to 20thDay
39%5%11%25%19%2
1843
21st to endDay
51%5%9%22%12%1
1782
November1st to 10thDay
34%413%28%17%3
1672
11th to 20thDay
50%5%9%20%13%3
1710
21st to endDay
53%410%22%9%2
1710
December1st to 10thDay
62%5%9%16%8%
1710
11th to 20thDay
60%48%21%6%1
1968
21st to endDay
74%46%9%6%
2783
January1st to 10thNight
60%6%7%17%10%
2648
11th to 20thNight
67%48%16%6%1
2660
21st to endNight
62%49%16%8%1
2695
February1st to 10thNight
62%411%15%7%1
2182
11th to 20thNight
54%5%11%19%11%1
2099
21st to endNight
57%5%10%16%10%2
1776
March1st to 10thNight
50%5%10%22%13%1
2160
11th to 20thNight
47%5%12%22%11%3
2033
21st to endNight
53%411%22%8%2
2126
April1st to 10thNight
44%6%11%24%13%2
1800
11th to 20thNight
44%410%20%17%5%
1775
21st to endNight
47%6%10%20%13%4
1625
May1st to 10thNight
52%7%10%20%9%2
1620
11th to 20thNight
44%6%13%22%13%2
1593
21st to endNight
36%7%17%23%14%4
1717
June1st to 10thNight
35%5%11%26%20%4
1440
11th to 20thNight
34%5%12%25%20%3
1440
21st to endNight
31%10%14%24%16%4
1440
July1st to 10thNight
34%9%14%22%15%6%
1400
11th to 20thNight
26%8%16%29%20%2
1392
21st to endNight
30%7%13%29%18%3
1581
August1st to 10thNight
29%8%16%28%18%2
1600
11th to 20thNight
32%7%13%27%19%2
1658
21st to endNight
28%6%14%24%22%5%
1980
September1st to 10thNight
34%7%11%22%20%6%
1826
11th to 20thNight
29%5%9%29%25%3
1980
21st to endNight
33%6%10%25%23%4
1980
October1st to 10thNight
31%5%11%25%23%4
1980
11th to 20thNight
42%48%25%19%2
2114
21st to endNight
47%48%24%15%2
2574
November1st to 10thNight
38%49%24%22%3
2406
11th to 20thNight
45%49%23%16%3
2470
21st to endNight
56%49%21%10%
2470
December1st to 10thNight
57%5%9%19%9%1
2470
11th to 20thNight
56%49%20%10%1
3224
21st to endNight
72%5%8%10%5%
4884

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
23%16%35%20%5%1
270
11th to 20thDay
24%17%36%16%5%1
270
21st to endDay
28%13%30%22%6%
267
February1st to 10thDay
32%12%36%17%3
240
11th to 20thDay
23%18%35%18%5%
240
21st to endDay
25%15%39%20%2
198
March1st to 10thDay
21%21%37%20%2
240
11th to 20thDay
25%13%34%18%8%1
366
21st to endDay
31%13%31%16%8%1
462
April1st to 10thDay
17%13%32%25%10%3
420
11th to 20thDay
20%13%31%21%12%3
412
21st to endDay
25%12%34%20%7%2
420
May1st to 10thDay
25%10%29%26%8%3
423
11th to 20thDay
22%6%28%23%15%6%
447
21st to endDay
15%323%27%20%13%
509
June1st to 10thDay
11%5%24%30%23%7%
630
11th to 20thDay
12%422%31%23%8%
630
21st to endDay
11%5%23%30%22%9%
630
July1st to 10thDay
12%213%24%28%20%
621
11th to 20thDay
8%317%31%25%15%
618
21st to endDay
10%312%29%31%16%
581
August1st to 10thDay
10%210%26%31%20%
446
11th to 20thDay
15%213%26%29%15%
439
21st to endDay
10%39%29%32%17%
495
September1st to 10thDay
12%5%14%24%32%13%
450
11th to 20thDay
11%213%27%28%19%
450
21st to endDay
16%6%20%24%23%11%
450
October1st to 10thDay
13%5%22%34%18%8%
450
11th to 20thDay
14%12%35%26%12%1
407
21st to endDay
31%11%34%22%3
297
November1st to 10thDay
14%14%30%24%15%3
270
11th to 20thDay
21%14%32%20%11%3
270
21st to endDay
27%8%37%22%5%1
270
December1st to 10thDay
21%19%36%17%7%1
270
11th to 20thDay
21%15%36%20%7%1
270
21st to endDay
30%15%33%18%4
297
January1st to 10thNight
25%14%33%23%5%
950
11th to 20thNight
27%12%36%21%4
950
21st to endNight
23%12%36%24%4
896
February1st to 10thNight
28%9%36%25%3
720
11th to 20thNight
22%12%37%27%3
703
21st to endNight
26%9%40%22%3
592
March1st to 10thNight
22%13%33%26%6%
720
11th to 20thNight
21%11%36%26%6%1
720
21st to endNight
25%9%32%27%6%1
740
April1st to 10thNight
17%9%37%28%8%
540
11th to 20thNight
20%9%32%29%10%1
533
21st to endNight
23%6%38%22%9%1
540
May1st to 10thNight
22%6%33%28%10%
540
11th to 20thNight
20%5%23%34%17%2
531
21st to endNight
9%421%39%25%2
584
June1st to 10thNight
11%321%46%19%1
540
11th to 20thNight
11%319%42%22%2
540
21st to endNight
7%222%39%27%2
540
July1st to 10thNight
10%110%34%37%8%
525
11th to 20thNight
8%212%39%33%5%
522
21st to endNight
9%210%40%36%2
591
August1st to 10thNight
9%29%39%37%5%
537
11th to 20thNight
7%110%42%34%6%
534
21st to endNight
7%113%36%39%4
594
September1st to 10thNight
14%411%33%33%5%
566
11th to 20thNight
9%214%35%34%6%
720
21st to endNight
13%419%35%25%3
720
October1st to 10thNight
12%5%23%36%20%5%
720
11th to 20thNight
21%8%29%28%12%1
720
21st to endNight
22%9%36%26%7%1
792
November1st to 10thNight
17%8%34%26%14%1
740
11th to 20thNight
18%14%31%29%8%1
760
21st to endNight
25%9%30%27%8%
760
December1st to 10thNight
23%11%36%25%5%
760
11th to 20thNight
26%7%35%25%6%
893
21st to endNight
30%12%32%22%4
1045
Page generated at 2024-01-19 10:28:30. Version ac07

Copyright 2024 Attilla Danko


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