Cox Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cox Field clear sky chart from 2005-11-05 to 2017-04-28.

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
48%
15058
24%
45633
16%
15015
56%
15015
28%
27911

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
26%
719
24%
2327
9%
716
43%
716
21%
1430
January16th to endNight
26%
768
24%
2418
10%
768
41%
768
21%
1548
February1st to 15thNight
30%
704
26%
2110
11%
700
45%
700
26%
1294
February16th to endNight
24%
631
25%
1893
9%
631
40%
631
24%
1163
March1st to 15thNight
31%
720
25%
2067
11%
720
42%
720
27%
1272
March16th to endNight
39%
768
24%
2112
12%
768
47%
768
30%
1288
April1st to 15thNight
41%
635
25%
1893
16%
635
50%
635
30%
1091
April16th to endNight
47%
534
26%
1704
18%
534
57%
534
31%
964
May1st to 15thNight
50%
495
23%
1485
15%
495
58%
495
32%
900
May16th to endNight
62%
513
21%
1538
16%
513
66%
513
35%
914
June1st to 15thNight
71%
495
19%
1485
16%
495
72%
495
31%
938
June16th to endNight
77%
495
18%
1485
16%
495
77%
495
36%
886
July1st to 15thNight
73%
465
13%
1395
13%
465
74%
465
27%
920
July16th to endNight
73%
522
15%
1469
13%
489
75%
489
29%
939
August1st to 15thNight
75%
494
17%
1534
20%
491
75%
491
29%
986
August16th to endNight
63%
525
17%
1750
18%
525
64%
525
22%
1168
September1st to 15thNight
67%
646
21%
1801
20%
646
68%
646
27%
1187
September16th to endNight
59%
657
23%
1815
17%
657
64%
657
28%
1196
October1st to 15thNight
55%
660
32%
1815
24%
660
63%
660
38%
1061
October16th to endNight
51%
704
34%
2104
26%
704
63%
704
37%
1153
November1st to 15thNight
49%
700
31%
2257
25%
700
61%
700
36%
1190
November16th to endNight
39%
720
27%
2340
17%
720
54%
720
29%
1337
December1st to 15thNight
36%
720
24%
2340
16%
720
48%
720
24%
1430
December16th to endNight
32%
768
21%
2496
14%
768
42%
768
19%
1656

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
12%5%25%5%35%5%5%7%40%
46055
Night
11%5%2442445%7%46%
45834
TransparencyDay
40%6%10%18%17%5%
45756
Night
35%5%10%19%19%7%
45637
SeeingDay
14%7%20%23%21%12%
4816
Night
14%8%22%28%21%4
15061

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 15thDay
16%6%24413346%44%
1611
16th to endDay
17%6%3433335%5%43%
1803
February1st to 15thDay
14%7%24323436%45%
1750
16th to endDay
16%5%35%324446%43%
1580
March1st to 15thDay
15%7%26%41345%5%43%
1892
16th to endDay
15%5%2443445%7%42%
2111
April1st to 15thDay
11%5%245%24446%46%
2064
16th to endDay
9%4145%2345%6%50%
2203
May1st to 15thDay
10%5%26%5%35%46%8%41%
2136
16th to endDay
8%425%6%35%5%5%10%42%
2223
June1st to 15thDay
8%426%8%47%6%6%10%32%
2145
16th to endDay
33146%5%7%7%8%11%40%
2145
July1st to 15thDay
10%5%37%7%5%8%7%9%11%25%
2145
16th to endDay
6%5%36%7%49%8%9%11%26%
2283
August1st to 15thDay
8%5%26%6%48%8%9%10%29%
2083
16th to endDay
14%6%36%7%47%7%7%9%26%
2100
September1st to 15thDay
13%6%36%7%46%7%6%7%31%
1818
16th to endDay
16%6%25%5%25%447%39%
1815
October1st to 15thDay
14%413312345%54%
1815
16th to endDay
12%31322333458%
1766
November1st to 15thDay
11%423423335%55%
1599
16th to endDay
13%424324447%49%
1620
December1st to 15thDay
15%7%25%423346%43%
1620
16th to endDay
22%8%26%5%2335%5%35%
1728
January1st to 15thNight
15%6%24423346%46%
2327
16th to endNight
17%6%35%42334444%
2418
February1st to 15thNight
14%4245%23346%47%
2103
16th to endNight
14%5%24424345%47%
1893
March1st to 15thNight
13%5%24334336%49%
2067
16th to endNight
11%6%23323448%49%
2112
April1st to 15thNight
12%42232345%7%50%
1893
16th to endNight
8%4245%3345%6%51%
1704
May1st to 15thNight
8%424435%46%9%47%
1484
16th to endNight
7%325%435%46%8%48%
1538
June1st to 15thNight
5%4235%45%6%7%11%43%
1485
16th to endNight
33245%35%5%9%13%43%
1485
July1st to 15thNight
7%325%6%36%7%8%12%36%
1485
16th to endNight
6%225%5%47%7%8%12%36%
1577
August1st to 15thNight
5%325%5%46%6%8%11%39%
1545
16th to endNight
11%6%36%6%35%5%6%11%35%
1750
September1st to 15thNight
8%5%26%5%36%5%7%9%38%
1801
16th to endNight
11%5%25%5%345%5%7%42%
1815
October1st to 15thNight
12%413213346%55%
1815
16th to endNight
9%31342233459%
2104
November1st to 15thNight
10%413223335%58%
2257
16th to endNight
13%423323345%52%
2340
December1st to 15thNight
13%6%25%323346%45%
2340
16th to endNight
19%6%35%424446%37%
2496

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%47%14%26%6%
1612
16th to endDay
42%36%16%22%8%
1803
February1st to 15thDay
40%37%19%22%6%
1752
16th to endDay
42%36%18%22%6%
1580
March1st to 15thDay
42%38%17%20%7%
1892
16th to endDay
40%5%9%21%18%4
2112
April1st to 15thDay
38%47%21%20%7%
2064
16th to endDay
33%5%10%19%24%6%
2203
May1st to 15thDay
39%6%12%18%19%3
2136
16th to endDay
36%7%14%25%14%2
2227
June1st to 15thDay
44%8%15%21%8%1
2145
16th to endDay
32%11%16%21%15%2
2145
July1st to 15thDay
45%13%18%15%6%1
2006
16th to endDay
43%13%17%17%7%
2128
August1st to 15thDay
42%11%17%18%8%
2070
16th to endDay
51%10%14%13%9%
2100
September1st to 15thDay
47%9%12%14%13%2
1818
16th to endDay
44%5%8%20%17%4
1815
October1st to 15thDay
33%310%20%24%7%
1815
16th to endDay
30%35%16%31%12%
1766
November1st to 15thDay
33%35%16%28%13%
1599
16th to endDay
36%47%15%25%10%
1620
December1st to 15thDay
42%38%20%17%7%
1620
16th to endDay
50%37%17%13%7%
1728
January1st to 15thNight
40%36%18%24%6%
2327
16th to endNight
43%35%16%21%9%
2418
February1st to 15thNight
38%2420%21%12%
2112
16th to endNight
38%36%17%24%8%
1893
March1st to 15thNight
37%39%19%20%9%
2067
16th to endNight
33%5%9%22%22%6%
2112
April1st to 15thNight
32%48%23%21%9%
1893
16th to endNight
31%5%9%22%21%9%
1704
May1st to 15thNight
33%7%13%20%21%3
1485
16th to endNight
31%6%15%26%15%3
1540
June1st to 15thNight
32%10%16%28%11%
1485
16th to endNight
29%8%20%23%15%2
1485
July1st to 15thNight
34%13%22%19%7%3
1395
16th to endNight
33%11%24%20%8%1
1469
August1st to 15thNight
35%10%20%22%10%1
1534
16th to endNight
42%9%17%16%12%1
1750
September1st to 15thNight
38%9%15%19%14%3
1801
16th to endNight
38%8%9%20%17%6%
1815
October1st to 15thNight
30%5%10%20%23%10%
1815
16th to endNight
28%3415%32%15%
2104
November1st to 15thNight
29%27%16%29%15%
2257
16th to endNight
33%36%16%25%12%
2340
December1st to 15thNight
39%48%19%20%8%
2340
16th to endNight
47%47%17%17%6%
2496

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
24%17%32%17%43
90
16th to endDay
18%28%44%17%
96
February1st to 15thDay
21%20%43%13%2
90
16th to endDay
24%12%50%11%1
81
March1st to 15thDay
19%16%35%19%7%1
182
16th to endDay
15%14%32%23%12%1
288
April1st to 15thDay
20%14%28%17%17%1
270
16th to endDay
10%9%27%25%19%7%
259
May1st to 15thDay
14%8%28%21%14%12%
228
16th to endDay
11%116%29%25%14%
267
June1st to 15thDay
10%212%24%30%20%
255
16th to endDay
110%33%27%27%
255
July1st to 15thDay
9%8%24%29%26%
245
16th to endDay
6%7%19%38%27%
270
August1st to 15thDay
10%1430%33%19%
253
16th to endDay
15%28%26%28%19%
268
September1st to 15thDay
15%17%20%34%19%
255
16th to endDay
17%115%34%22%8%
254
October1st to 15thDay
19%421%25%21%7%
255
16th to endDay
16%6%17%27%22%9%
272
November1st to 15thDay
27%16%22%19%12%1
107
16th to endDay
13%12%35%26%10%2
90
December1st to 15thDay
22%16%36%16%7%
90
16th to endDay
37%10%32%13%5%1
96
January1st to 15thNight
20%18%28%24%7%
720
16th to endNight
21%16%31%26%3
768
February1st to 15thNight
19%14%30%29%5%
704
16th to endNight
17%19%35%23%3
631
March1st to 15thNight
17%14%33%27%6%
720
16th to endNight
16%11%27%28%14%
768
April1st to 15thNight
14%13%27%27%15%
635
16th to endNight
11%8%27%31%18%1
534
May1st to 15thNight
9%429%28%24%3
495
16th to endNight
9%115%35%31%5%
515
June1st to 15thNight
6%112%35%35%9%
495
16th to endNight
317%32%42%13%
495
July1st to 15thNight
7%17%27%42%13%
465
16th to endNight
6%6%24%50%11%
522
August1st to 15thNight
5%5%28%47%13%
494
16th to endNight
14%17%23%39%14%
525
September1st to 15thNight
10%18%24%43%11%
646
16th to endNight
13%213%35%31%3
657
October1st to 15thNight
15%419%31%22%6%
660
16th to endNight
11%8%23%29%23%3
704
November1st to 15thNight
13%8%24%30%20%2
700
16th to endNight
15%13%27%27%14%
720
December1st to 15thNight
16%12%29%28%11%1
720
16th to endNight
23%12%27%27%8%
768
Page generated at 2017-04-29 09:45:03. Version ac04

Copyright 2017 A. Danko


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