Coyle Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coyle Field 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
38%
14976
20%
46489
11%
14945
48%
14945
25%
29441

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%
720
21%
2506
10%
716
42%
716
20%
1556
January16th to endNight
23%
768
21%
2554
8%
768
41%
768
22%
1579
February1st to 15thNight
20%
704
18%
2222
6%
701
36%
701
22%
1404
February16th to endNight
22%
631
26%
1893
9%
631
43%
631
24%
1163
March1st to 15thNight
26%
720
20%
2134
10%
720
40%
720
25%
1365
March16th to endNight
28%
768
22%
2004
9%
768
37%
768
27%
1365
April1st to 15thNight
28%
718
18%
1796
6%
718
35%
718
28%
1219
April16th to endNight
37%
720
18%
1800
7%
720
41%
720
30%
1221
May1st to 15thNight
33%
532
17%
1612
9%
532
41%
532
21%
1101
May16th to endNight
47%
374
15%
1497
14%
374
53%
374
18%
951
June1st to 15thNight
51%
360
14%
1440
16%
360
57%
360
18%
915
June16th to endNight
62%
360
16%
1440
19%
360
67%
360
25%
818
July1st to 15thNight
58%
340
12%
1360
16%
340
60%
340
21%
835
July16th to endNight
65%
376
16%
1418
18%
354
70%
354
26%
792
August1st to 15thNight
65%
596
18%
1645
13%
594
66%
594
34%
1022
August16th to endNight
64%
700
17%
1750
9%
700
65%
700
33%
1160
September1st to 15thNight
56%
660
25%
1650
15%
660
60%
660
35%
1079
September16th to endNight
57%
657
24%
1798
20%
657
59%
657
32%
1150
October1st to 15thNight
46%
660
23%
1939
18%
660
53%
660
29%
1202
October16th to endNight
35%
704
26%
2175
14%
704
50%
704
28%
1313
November1st to 15thNight
37%
700
23%
2277
15%
700
50%
700
26%
1386
November16th to endNight
33%
720
20%
2371
12%
720
44%
720
21%
1504
December1st to 15thNight
26%
720
17%
2520
7%
720
39%
720
18%
1626
December16th to endNight
23%
768
21%
2688
7%
768
41%
768
19%
1715

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%5%2442445%7%41%
47491
Night
15%5%2442445%7%43%
46659
Cloud CoverDay
14%6%2443445%7%41%
47500
Night
15%6%24424447%43%
46665
TransparencyDay
40%6%12%22%15%2
47179
Night
40%5%11%22%17%2
46489
SeeingDay
18%6%25%26%16%6%
5674
Night
18%7%28%31%12%1
14977

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
13%6%25%435%446%43%
1432
16th to endDay
17%6%1442335%6%44%
1668
February1st to 15thDay
15%7%25%423446%41%
1639
16th to endDay
13%6%27%5%3345%6%41%
1580
March1st to 15thDay
16%5%24424446%41%
1814
16th to endDay
18%6%24424345%42%
2220
April1st to 15thDay
17%6%24323347%43%
2152
16th to endDay
15%5%244235%5%7%43%
2160
May1st to 15thDay
18%5%33434447%38%
2349
16th to endDay
15%5%3443445%7%40%
2618
June1st to 15thDay
14%6%245%35%45%9%37%
2520
16th to endDay
10%4246%36%5%7%9%39%
2520
July1st to 15thDay
10%6%25%5%46%6%6%8%37%
2520
16th to endDay
10%5%246%37%7%8%9%34%
2654
August1st to 15thDay
11%426%6%345%6%8%41%
2204
16th to endDay
11%5%245%3446%8%42%
2100
September1st to 15thDay
14%5%13333348%46%
1980
16th to endDay
15%6%26%5%24347%40%
1831
October1st to 15thDay
18%5%24413437%44%
1689
16th to endDay
17%5%24323246%48%
1697
November1st to 15thDay
18%5%24423336%46%
1581
16th to endDay
16%4245%24446%45%
1587
December1st to 15thDay
16%5%2442345%6%43%
1440
16th to endDay
20%6%35%323447%39%
1536
January1st to 15thNight
17%6%2432345%7%42%
2506
16th to endNight
17%6%14324446%43%
2554
February1st to 15thNight
15%7%34424346%42%
2221
16th to endNight
16%425%41435%5%47%
1893
March1st to 15thNight
18%5%14423247%44%
2121
16th to endNight
18%6%35%32332445%
2004
April1st to 15thNight
16%7%25%323336%44%
1796
16th to endNight
16%6%3432445%7%42%
1800
May1st to 15thNight
19%7%25%32435%7%36%
1612
16th to endNight
16%7%345%235%5%7%39%
1495
June1st to 15thNight
16%5%25%435%448%39%
1440
16th to endNight
8%5%246%35%46%10%43%
1440
July1st to 15thNight
9%5%36%6%25%5%6%11%37%
1440
16th to endNight
7%3245%45%5%7%10%42%
1514
August1st to 15thNight
8%425%5%3446%9%46%
1655
16th to endNight
11%5%25%43446%8%44%
1750
September1st to 15thNight
13%424423448%46%
1650
16th to endNight
14%6%2332335%7%46%
1798
October1st to 15thNight
17%5%2432235%6%46%
1939
16th to endNight
17%413323345%49%
2175
November1st to 15thNight
15%6%35%323335%48%
2277
16th to endNight
15%6%25%425%45%6%40%
2371
December1st to 15thNight
18%5%35%42445%5%38%
2520
16th to endNight
17%6%35%425%346%40%
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
12%6%36%425%436%42%
1432
16th to endDay
17%6%14424446%44%
1668
February1st to 15thDay
14%7%25%424447%41%
1639
16th to endDay
13%6%36%5%2445%6%41%
1580
March1st to 15thDay
16%5%34425%446%41%
1824
16th to endDay
17%6%24324345%43%
2219
April1st to 15thDay
17%7%24233346%43%
2152
16th to endDay
15%5%244245%5%7%43%
2160
May1st to 15thDay
18%6%335%2445%7%38%
2349
16th to endDay
15%6%3442445%8%39%
2618
June1st to 15thDay
14%6%245%36%5%5%9%36%
2520
16th to endDay
10%4246%35%6%6%9%39%
2520
July1st to 15thDay
9%6%35%5%45%6%6%8%37%
2520
16th to endDay
9%5%35%5%46%6%8%10%34%
2654
August1st to 15thDay
10%5%26%6%345%6%8%40%
2204
16th to endDay
12%424425%6%7%8%41%
2100
September1st to 15thDay
13%5%1433435%8%46%
1980
16th to endDay
14%6%26%5%23447%40%
1831
October1st to 15thDay
17%6%24322346%44%
1689
16th to endDay
17%5%24323246%48%
1697
November1st to 15thDay
17%5%24423347%45%
1581
16th to endDay
16%324424346%45%
1587
December1st to 15thDay
16%5%24432447%43%
1440
16th to endDay
20%6%25%313447%39%
1536
January1st to 15thNight
17%5%3432345%7%42%
2506
16th to endNight
18%6%2432445%6%43%
2554
February1st to 15thNight
15%7%24423346%42%
2214
16th to endNight
16%424324445%47%
1893
March1st to 15thNight
17%6%23422337%44%
2134
16th to endNight
18%6%35%32332445%
2004
April1st to 15thNight
16%7%25%323446%43%
1796
16th to endNight
16%6%2442445%7%41%
1800
May1st to 15thNight
19%7%25%425%35%8%36%
1612
16th to endNight
17%7%15%5%245%47%38%
1495
June1st to 15thNight
15%6%26%435%448%39%
1440
16th to endNight
8%425%5%345%5%11%43%
1440
July1st to 15thNight
8%6%26%7%25%5%5%12%37%
1440
16th to endNight
6%335%6%45%47%10%41%
1514
August1st to 15thNight
7%5%25%4345%5%9%46%
1655
16th to endNight
11%5%2443446%7%44%
1750
September1st to 15thNight
12%5%2442345%8%46%
1650
16th to endNight
14%7%13323447%46%
1798
October1st to 15thNight
17%5%1432235%6%46%
1939
16th to endNight
16%423323345%49%
2175
November1st to 15thNight
15%6%34423235%48%
2277
16th to endNight
15%5%35%43445%6%40%
2371
December1st to 15thNight
18%5%35%43345%6%38%
2520
16th to endNight
17%6%35%424446%39%
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
41%6%12%20%14%4
1433
16th to endDay
40%410%25%15%3
1668
February1st to 15thDay
43%411%24%14%2
1642
16th to endDay
42%5%9%25%13%2
1580
March1st to 15thDay
43%413%22%13%2
1824
16th to endDay
41%5%8%23%16%3
2220
April1st to 15thDay
42%49%23%14%5%
2152
16th to endDay
38%6%12%17%21%3
2160
May1st to 15thDay
44%6%11%20%14%2
2349
16th to endDay
41%7%14%22%11%1
2622
June1st to 15thDay
42%8%12%22%11%1
2520
16th to endDay
37%10%13%21%15%1
2520
July1st to 15thDay
41%7%12%23%13%2
2371
16th to endDay
39%9%13%24%10%2
2487
August1st to 15thDay
37%7%15%22%16%1
2190
16th to endDay
35%7%14%21%18%2
2100
September1st to 15thDay
36%5%13%20%22%2
1980
16th to endDay
42%49%17%22%2
1831
October1st to 15thDay
40%411%23%17%2
1689
16th to endDay
38%39%26%20%2
1697
November1st to 15thDay
40%310%23%18%2
1581
16th to endDay
40%310%26%17%2
1587
December1st to 15thDay
40%5%15%22%13%2
1440
16th to endDay
44%413%21%13%1
1536
January1st to 15thNight
41%5%11%21%17%3
2506
16th to endNight
41%410%25%15%1
2554
February1st to 15thNight
42%311%24%14%3
2222
16th to endNight
37%49%24%19%4
1893
March1st to 15thNight
41%411%22%16%3
2134
16th to endNight
44%39%20%17%4
2004
April1st to 15thNight
41%410%21%16%4
1796
16th to endNight
41%5%9%17%22%3
1800
May1st to 15thNight
47%5%9%18%16%2
1612
16th to endNight
45%6%13%18%14%2
1497
June1st to 15thNight
44%6%11%19%17%
1440
16th to endNight
35%6%14%25%16%2
1440
July1st to 15thNight
39%8%15%20%12%2
1360
16th to endNight
33%7%19%25%12%1
1418
August1st to 15thNight
33%7%14%22%19%1
1645
16th to endNight
37%6%12%20%20%2
1750
September1st to 15thNight
36%6%12%22%20%2
1650
16th to endNight
37%5%8%22%23%2
1798
October1st to 15thNight
38%412%23%17%3
1939
16th to endNight
37%38%27%19%2
2175
November1st to 15thNight
39%39%22%19%6%
2277
16th to endNight
43%410%22%15%2
2371
December1st to 15thNight
45%5%12%21%12%1
2520
16th to endNight
43%5%12%22%13%2
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%21%38%13%8%1
60
16th to endDay
25%13%34%22%3
86
February1st to 15thDay
19%21%39%18%1
155
16th to endDay
15%15%44%21%2
239
March1st to 15thDay
16%15%34%25%7%
270
16th to endDay
21%10%37%21%5%3
288
April1st to 15thDay
22%9%34%22%8%2
270
16th to endDay
20%5%30%27%10%5%
270
May1st to 15thDay
28%12%24%19%11%3
288
16th to endDay
21%319%26%22%5%
331
June1st to 15thDay
19%326%26%18%6%
315
16th to endDay
12%225%36%18%5%
315
July1st to 15thDay
16%18%31%25%6%
305
16th to endDay
9%117%34%26%9%
326
August1st to 15thDay
12%117%30%26%11%
297
16th to endDay
10%17%29%30%19%
268
September1st to 15thDay
14%121%23%20%18%
255
16th to endDay
22%215%26%19%13%
254
October1st to 15thDay
22%316%29%21%6%
255
16th to endDay
14%9%31%27%14%3
261
November1st to 15thDay
19%9%25%27%14%2
235
16th to endDay
19%9%32%22%12%2
207
December1st to 15thDay
16%20%30%18%15%
60
16th to endDay
31%7%42%17%1
64
January1st to 15thNight
19%14%34%25%5%
720
16th to endNight
21%10%40%25%2
768
February1st to 15thNight
19%13%39%25%1
704
16th to endNight
19%14%38%25%2
631
March1st to 15thNight
20%10%38%25%5%
720
16th to endNight
21%6%37%24%8%1
768
April1st to 15thNight
20%10%35%27%5%
718
16th to endNight
19%432%34%8%
720
May1st to 15thNight
22%7%30%29%8%
532
16th to endNight
19%219%38%18%1
375
June1st to 15thNight
19%319%38%17%1
360
16th to endNight
8%217%50%21%
360
July1st to 15thNight
12%116%46%22%
340
16th to endNight
9%113%44%28%3
376
August1st to 15thNight
10%112%45%27%2
596
16th to endNight
12%211%38%30%5%
700
September1st to 15thNight
15%216%36%25%4
660
16th to endNight
19%114%33%26%4
657
October1st to 15thNight
20%421%30%19%2
660
16th to endNight
18%8%32%28%11%
704
November1st to 15thNight
18%8%29%28%13%2
700
16th to endNight
18%9%31%29%10%1
720
December1st to 15thNight
23%9%33%23%9%1
720
16th to endNight
20%11%39%25%3
768
Page generated at 2017-08-13 14:16:12. Version ac04

Copyright 2017 A. Danko


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