Coyote Run Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coyote Run Observatory clear sky chart from 2005-11-05 to 2017-08-12.

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
36%
15959
18%
46552
10%
15912
44%
15912
27%
30010

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
27%
900
14%
2443
6%
895
34%
895
21%
1723
January16th to endNight
24%
960
15%
2496
5%
960
31%
960
20%
1828
February1st to 15thNight
24%
879
11%
2288
2%
875
29%
875
21%
1663
February16th to endNight
27%
753
18%
2015
5%
753
37%
753
25%
1358
March1st to 15thNight
34%
540
18%
1980
11%
540
44%
540
23%
1205
March16th to endNight
27%
576
14%
2112
9%
576
35%
576
16%
1450
April1st to 15thNight
28%
539
16%
1830
11%
539
38%
539
22%
1172
April16th to endNight
28%
540
18%
1637
11%
540
38%
540
20%
1159
May1st to 15thNight
37%
540
17%
1599
10%
540
44%
540
26%
1043
May16th to endNight
41%
563
15%
1498
5%
561
47%
561
30%
985
June1st to 15thNight
49%
540
14%
1440
5%
540
53%
540
33%
924
June16th to endNight
55%
540
19%
1440
7%
540
59%
540
47%
811
July1st to 15thNight
64%
510
19%
1360
8%
510
68%
510
49%
740
July16th to endNight
69%
564
23%
1553
17%
531
72%
531
48%
805
August1st to 15thNight
64%
527
22%
1575
21%
524
68%
524
41%
874
August16th to endNight
62%
525
23%
1619
23%
525
67%
525
39%
894
September1st to 15thNight
57%
495
26%
1675
24%
495
67%
495
38%
863
September16th to endNight
46%
495
24%
1818
17%
495
58%
495
33%
956
October1st to 15thNight
37%
660
26%
1980
15%
660
47%
660
32%
1161
October16th to endNight
35%
704
19%
2112
11%
704
42%
704
27%
1325
November1st to 15thNight
34%
849
24%
2354
10%
849
44%
849
30%
1459
November16th to endNight
27%
900
17%
2520
8%
900
34%
900
23%
1696
December1st to 15thNight
21%
900
11%
2520
3%
900
28%
900
18%
1865
December16th to endNight
20%
960
14%
2688
5%
960
28%
960
15%
2051

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
13%7%36%5%3445%7%38%
47424
Night
11%7%35%5%24447%43%
46732
Cloud CoverDay
13%7%36%5%3445%7%38%
47435
Night
11%7%35%5%24447%43%
46736
Cloud CoverDay
13%7%36%5%3445%7%38%
47433
Night
11%7%35%5%24447%43%
46736
TransparencyDay
44%5%14%22%11%1
47122
Night
40%5%14%24%13%1
46552
SeeingDay
15%7%29%29%14%3
5921
Night
15%8%33%30%11%
15960

By Month

Percentage Cloud Cover NE (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
9%10%5%8%8%35%46%7%30%
1492
16th to endDay
10%11%7%10%7%45%45%8%24%
1728
February1st to 15thDay
11%11%6%9%7%35%446%29%
1575
16th to endDay
12%7%49%7%26%5%5%6%32%
1470
March1st to 15thDay
13%10%6%8%5%24436%33%
1969
16th to endDay
19%10%36%5%2446%7%29%
2112
April1st to 15thDay
16%8%36%5%2446%7%34%
2118
16th to endDay
25%10%36%423345%28%
2322
May1st to 15thDay
20%7%35%5%3435%6%34%
2352
16th to endDay
17%5%25%5%35%45%7%37%
2617
June1st to 15thDay
14%5%25%4245%5%8%39%
2520
16th to endDay
7%424435%5%6%8%46%
2520
July1st to 15thDay
5%3235%35%6%6%9%49%
2520
16th to endDay
6%3134245%6%9%50%
2505
August1st to 15thDay
9%4245%36%5%6%8%41%
2289
16th to endDay
11%5%244245%5%8%44%
2231
September1st to 15thDay
12%41342446%7%47%
1954
16th to endDay
11%42342345%7%50%
1801
October1st to 15thDay
13%6%24433345%48%
1650
16th to endDay
14%8%35%423345%44%
1760
November1st to 15thDay
10%5%35%423447%47%
1503
16th to endDay
14%9%35%5%34338%38%
1440
December1st to 15thDay
14%9%5%11%8%5%5%435%26%
1440
16th to endDay
17%13%5%8%8%2445%7%23%
1536
January1st to 15thNight
8%8%46%7%35%5%6%8%33%
2443
16th to endNight
11%10%5%7%5%35%45%7%32%
2496
February1st to 15thNight
11%12%5%6%6%34346%33%
2285
16th to endNight
9%7%36%6%35%447%40%
2015
March1st to 15thNight
13%6%27%423347%43%
1968
16th to endNight
14%9%5%7%5%33345%35%
2112
April1st to 15thNight
16%6%25%5%24446%41%
1830
16th to endNight
20%8%36%5%33345%36%
1637
May1st to 15thNight
15%5%245%24447%44%
1599
16th to endNight
13%5%2442445%10%40%
1496
June1st to 15thNight
9%424425%5%7%9%43%
1440
16th to endNight
6%21331345%9%57%
1440
July1st to 15thNight
321321445%10%60%
1440
16th to endNight
32132245%5%10%58%
1660
August1st to 15thNight
432442346%7%55%
1585
16th to endNight
8%413422436%57%
1619
September1st to 15thNight
9%413322346%59%
1675
16th to endNight
8%414333447%54%
1818
October1st to 15thNight
14%5%1342234452%
1980
16th to endNight
16%6%2431335%5%46%
2112
November1st to 15thNight
10%6%25%423345%49%
2354
16th to endNight
11%9%36%5%24446%41%
2520
December1st to 15thNight
13%11%47%7%35%45%6%31%
2520
16th to endNight
17%11%5%9%6%33445%28%
2688

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
9%10%5%8%8%35%46%6%30%
1492
16th to endDay
10%10%7%10%7%45%45%8%24%
1728
February1st to 15thDay
11%11%5%9%8%35%446%28%
1575
16th to endDay
12%7%39%7%26%5%5%6%32%
1470
March1st to 15thDay
13%10%6%8%5%24437%33%
1980
16th to endDay
19%10%36%5%2445%7%29%
2112
April1st to 15thDay
16%8%36%5%2446%7%34%
2118
16th to endDay
25%10%36%424345%28%
2322
May1st to 15thDay
20%7%35%5%3435%6%34%
2352
16th to endDay
17%6%25%5%25%45%7%37%
2617
June1st to 15thDay
14%5%25%4345%5%8%39%
2520
16th to endDay
7%424435%5%6%8%46%
2520
July1st to 15thDay
5%323435%6%6%9%49%
2520
16th to endDay
6%3134245%6%9%50%
2505
August1st to 15thDay
9%435%5%35%5%6%8%41%
2289
16th to endDay
11%5%2442445%8%44%
2231
September1st to 15thDay
12%41342446%7%47%
1954
16th to endDay
11%42342345%7%50%
1801
October1st to 15thDay
14%6%14433336%48%
1650
16th to endDay
14%8%35%423345%44%
1760
November1st to 15thDay
10%5%35%423447%47%
1503
16th to endDay
14%9%35%5%34347%38%
1440
December1st to 15thDay
14%9%5%11%8%5%5%435%26%
1440
16th to endDay
17%13%5%8%8%2345%7%23%
1536
January1st to 15thNight
8%8%46%7%35%6%6%8%33%
2443
16th to endNight
11%10%5%7%5%35%45%7%32%
2496
February1st to 15thNight
10%13%5%6%6%34346%34%
2278
16th to endNight
9%7%36%6%35%447%40%
2015
March1st to 15thNight
13%6%27%423347%43%
1980
16th to endNight
14%10%5%7%5%3334435%
2112
April1st to 15thNight
16%6%25%434446%42%
1830
16th to endNight
20%8%36%5%33345%36%
1637
May1st to 15thNight
15%5%245%24447%44%
1598
16th to endNight
13%4344345%5%10%41%
1496
June1st to 15thNight
9%424435%6%7%9%43%
1440
16th to endNight
6%21331345%8%58%
1440
July1st to 15thNight
32132145%5%9%60%
1440
16th to endNight
32132245%5%10%59%
1660
August1st to 15thNight
432442345%8%55%
1585
16th to endNight
8%414422436%57%
1619
September1st to 15thNight
9%412323346%59%
1675
16th to endNight
8%414333347%54%
1818
October1st to 15thNight
14%5%2342233452%
1980
16th to endNight
16%6%23313345%46%
2112
November1st to 15thNight
10%6%25%5%2335%5%49%
2354
16th to endNight
11%9%36%5%24446%41%
2520
December1st to 15thNight
13%11%47%7%35%45%6%31%
2520
16th to endNight
17%11%5%8%6%33445%28%
2688

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 15thDay
9%10%5%9%8%35%46%7%30%
1492
16th to endDay
10%11%6%10%7%45%448%24%
1728
February1st to 15thDay
12%11%5%9%8%34446%28%
1575
16th to endDay
12%7%49%7%26%5%46%32%
1470
March1st to 15thDay
13%10%6%8%5%24336%33%
1980
16th to endDay
19%10%36%5%3446%6%29%
2110
April1st to 15thDay
16%8%36%5%3446%6%34%
2118
16th to endDay
25%10%36%423445%29%
2322
May1st to 15thDay
20%6%35%5%34346%34%
2352
16th to endDay
17%5%25%5%25%45%7%37%
2617
June1st to 15thDay
15%5%25%5%3445%8%39%
2520
16th to endDay
8%414435%5%6%8%46%
2520
July1st to 15thDay
5%314426%5%6%9%49%
2520
16th to endDay
6%314425%6%6%9%50%
2505
August1st to 15thDay
9%425%6%35%46%8%41%
2289
16th to endDay
11%5%24425%46%8%44%
2231
September1st to 15thDay
12%41342446%7%47%
1954
16th to endDay
11%42442345%7%50%
1801
October1st to 15thDay
13%6%24424345%48%
1650
16th to endDay
14%8%35%423345%44%
1760
November1st to 15thDay
10%5%25%424447%47%
1503
16th to endDay
13%9%36%5%34337%38%
1440
December1st to 15thDay
14%10%5%10%8%5%5%435%26%
1440
16th to endDay
16%13%5%9%8%2345%6%23%
1536
January1st to 15thNight
8%8%46%7%35%6%6%8%33%
2443
16th to endNight
11%11%5%7%5%35%46%6%32%
2496
February1st to 15thNight
10%13%5%6%7%33446%33%
2278
16th to endNight
9%8%45%6%35%447%40%
2015
March1st to 15thNight
13%6%26%5%13447%43%
1980
16th to endNight
14%10%47%5%3434435%
2112
April1st to 15thNight
16%6%25%424446%42%
1830
16th to endNight
20%8%36%5%24335%36%
1637
May1st to 15thNight
15%5%24433447%44%
1598
16th to endNight
13%5%2442445%10%41%
1496
June1st to 15thNight
9%424426%6%7%8%44%
1440
16th to endNight
6%21342335%9%57%
1440
July1st to 15thNight
32321445%9%60%
1440
16th to endNight
32132245%5%10%59%
1660
August1st to 15thNight
5%3244135%5%7%55%
1585
16th to endNight
8%414423336%58%
1619
September1st to 15thNight
9%313223336%59%
1675
16th to endNight
8%5%14423347%54%
1818
October1st to 15thNight
14%5%13423335%52%
1980
16th to endNight
16%7%24312446%46%
2112
November1st to 15thNight
10%6%25%424345%49%
2354
16th to endNight
11%8%46%424446%41%
2520
December1st to 15thNight
13%10%47%7%35%346%31%
2520
16th to endNight
17%11%5%8%6%34445%28%
2688

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
52%415%18%9%
1493
16th to endDay
57%5%15%15%4
1728
February1st to 15thDay
57%413%17%6%
1576
16th to endDay
50%5%15%17%8%1
1470
March1st to 15thDay
52%415%20%6%
1980
16th to endDay
53%6%15%19%4
2112
April1st to 15thDay
47%6%13%22%8%1
2118
16th to endDay
56%5%11%19%7%
2322
May1st to 15thDay
50%5%12%22%8%
2352
16th to endDay
45%6%14%19%12%1
2621
June1st to 15thDay
42%6%15%23%11%
2520
16th to endDay
32%7%16%26%14%2
2520
July1st to 15thDay
30%8%16%28%13%3
2371
16th to endDay
28%7%17%29%15%2
2349
August1st to 15thDay
38%6%15%26%10%1
2275
16th to endDay
35%6%13%26%14%3
2231
September1st to 15thDay
33%7%14%25%17%1
1954
16th to endDay
33%5%13%32%14%
1801
October1st to 15thDay
38%412%23%19%1
1650
16th to endDay
41%415%25%12%
1760
November1st to 15thDay
36%414%23%19%1
1503
16th to endDay
46%5%18%20%9%
1440
December1st to 15thDay
60%5%12%12%7%1
1440
16th to endDay
60%412%14%6%
1536
January1st to 15thNight
45%7%14%21%11%
2443
16th to endNight
50%5%16%19%7%
2496
February1st to 15thNight
50%413%20%9%
2288
16th to endNight
43%415%23%11%2
2015
March1st to 15thNight
40%416%25%10%1
1980
16th to endNight
51%412%22%6%
2112
April1st to 15thNight
42%5%12%24%12%1
1830
16th to endNight
50%5%9%20%11%2
1637
May1st to 15thNight
39%7%13%24%14%1
1599
16th to endNight
38%6%17%22%13%2
1498
June1st to 15thNight
33%8%18%24%13%1
1440
16th to endNight
24%5%16%29%21%3
1440
July1st to 15thNight
19%7%17%33%17%5%
1360
16th to endNight
19%7%16%33%19%4
1553
August1st to 15thNight
26%6%15%31%17%2
1575
16th to endNight
28%5%13%30%18%4
1619
September1st to 15thNight
26%413%29%22%2
1675
16th to endNight
29%413%31%19%1
1818
October1st to 15thNight
35%311%27%20%2
1980
16th to endNight
38%5%15%24%15%1
2112
November1st to 15thNight
36%412%24%20%2
2354
16th to endNight
43%5%16%22%11%1
2520
December1st to 15thNight
53%5%15%18%6%
2520
16th to endNight
58%411%15%9%
2688

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
16%8%40%24%8%1
90
16th to endDay
15%9%37%32%32
96
February1st to 15thDay
13%22%33%28%2
90
16th to endDay
20%11%34%23%9%
81
March1st to 15thDay
23%14%38%22%1
90
16th to endDay
34%7%27%25%6%
96
April1st to 15thDay
21%8%35%27%7%
237
16th to endDay
30%15%25%19%6%2
432
May1st to 15thDay
22%13%28%28%5%2
468
16th to endDay
20%8%30%24%13%2
517
June1st to 15thDay
15%429%31%14%3
495
16th to endDay
7%7%35%33%12%3
495
July1st to 15thDay
6%129%34%22%5%
475
16th to endDay
7%224%38%21%5%
515
August1st to 15thDay
8%222%36%25%4
474
16th to endDay
16%320%31%23%4
399
September1st to 15thDay
12%330%29%20%3
229
16th to endDay
12%8%30%22%22%4
90
October1st to 15thDay
47%37%30%15%4
90
16th to endDay
17%10%39%20%11%
96
November1st to 15thDay
47%35%34%14%3
90
16th to endDay
41%12%26%15%4
90
December1st to 15thDay
18%15%44%12%7%1
90
16th to endDay
32%22%29%12%3
96
January1st to 15thNight
13%12%39%26%7%1
900
16th to endNight
17%11%37%28%5%
960
February1st to 15thNight
17%11%37%25%6%
880
16th to endNight
13%10%41%24%8%1
753
March1st to 15thNight
17%7%35%29%9%
540
16th to endNight
19%10%36%25%7%
576
April1st to 15thNight
20%9%37%26%6%
539
16th to endNight
23%9%34%21%9%1
540
May1st to 15thNight
16%8%35%29%10%
540
16th to endNight
16%6%29%33%13%
563
June1st to 15thNight
10%429%41%14%
540
16th to endNight
6%330%45%13%
540
July1st to 15thNight
4126%41%24%1
510
16th to endNight
3121%47%24%1
564
August1st to 15thNight
6%121%42%26%2
527
16th to endNight
10%319%40%22%3
525
September1st to 15thNight
13%124%37%20%2
495
16th to endNight
10%6%33%29%18%1
495
October1st to 15thNight
16%8%34%28%12%
660
16th to endNight
20%8%30%30%8%
704
November1st to 15thNight
14%12%35%26%10%
849
16th to endNight
15%14%39%23%7%
900
December1st to 15thNight
18%10%41%25%4
900
16th to endNight
23%9%36%23%7%
960
Page generated at 2017-08-13 13:16:50. Version ac04

Copyright 2017 A. Danko


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