Denton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Denton clear sky chart from 2005-11-05 to 2018-10-27.

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
53%
17047
30%
51314
21%
17003
62%
17003
41%
27592

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
42%
972
31%
2522
14%
970
53%
970
42%
1458
January16th to endNight
41%
1040
35%
2704
14%
1040
54%
1040
45%
1528
February1st to 15thNight
37%
819
28%
2346
12%
814
48%
814
36%
1341
February16th to endNight
27%
681
29%
2047
10%
681
42%
681
35%
1144
March1st to 15thNight
35%
585
29%
2145
18%
585
49%
585
30%
1167
March16th to endNight
38%
624
25%
2288
16%
624
51%
624
31%
1217
April1st to 15thNight
34%
584
25%
2142
14%
584
50%
584
31%
1112
April16th to endNight
39%
579
28%
1810
19%
579
55%
579
38%
972
May1st to 15thNight
41%
585
25%
1755
15%
585
57%
585
35%
1016
May16th to endNight
56%
610
26%
1828
23%
609
66%
609
43%
996
June1st to 15thNight
74%
585
25%
1755
26%
585
79%
585
54%
849
June16th to endNight
78%
585
26%
1755
28%
585
80%
585
50%
875
July1st to 15thNight
81%
555
24%
1665
29%
555
83%
555
48%
854
July16th to endNight
88%
612
32%
1738
39%
579
88%
579
55%
827
August1st to 15thNight
89%
575
38%
1717
44%
572
90%
572
60%
783
August16th to endNight
81%
621
30%
2043
36%
621
83%
621
43%
1022
September1st to 15thNight
70%
585
23%
2145
28%
585
71%
585
32%
1155
September16th to endNight
73%
582
34%
2145
35%
582
76%
582
39%
1051
October1st to 15thNight
63%
660
34%
2220
28%
660
70%
660
42%
1115
October16th to endNight
52%
816
37%
2448
22%
816
63%
816
46%
1236
November1st to 15thNight
53%
802
30%
2322
16%
802
61%
802
44%
1237
November16th to endNight
44%
975
36%
2535
17%
975
55%
975
42%
1456
December1st to 15thNight
42%
975
32%
2535
16%
975
51%
975
40%
1507
December16th to endNight
36%
1040
29%
2704
12%
1040
47%
1040
36%
1674

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
9%3133233419%46%
52231
Night
7%3132122319%50%
51511
Cloud CoverDay
10%413324446%53%
52229
Night
9%313323347%57%
51511
TransparencyDay
31%410%24%22%7%
51929
Night
27%39%23%25%10%
51316
SeeingDay
11%318%28%27%10%
7040
Night
11%5%26%36%18%1
17051

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
10%4122113219%49%
1746
16th to endDay
8%222223319%51%
1872
February1st to 15thDay
11%5%143222219%45%
1856
16th to endDay
15%4122112218%45%
1710
March1st to 15thDay
15%4123233220%40%
2145
16th to endDay
10%4133122220%46%
2288
April1st to 15thDay
9%4132232420%45%
2136
16th to endDay
10%4132222321%45%
2420
May1st to 15thDay
10%4133233320%42%
2526
16th to endDay
7%4244233422%39%
2638
June1st to 15thDay
4234234423%46%
2535
16th to endDay
31132234422%50%
2535
July1st to 15thDay
311333345%22%44%
2535
16th to endDay
21232445%23%48%
2674
August1st to 15thDay
32232445%15%54%
2486
16th to endDay
6%3134246%6%16%43%
2507
September1st to 15thDay
10%3134235%5%14%44%
2145
16th to endDay
9%41332335%14%48%
2145
October1st to 15thDay
10%3132133312%52%
2054
16th to endDay
9%3121122211%60%
2033
November1st to 15thDay
9%3133232318%49%
1863
16th to endDay
10%3121112219%52%
1755
December1st to 15thDay
14%6%133122319%41%
1755
16th to endDay
14%4133123319%40%
1872
January1st to 15thNight
8%3133123319%49%
2522
16th to endNight
8%221111219%55%
2704
February1st to 15thNight
10%5%132123219%47%
2337
16th to endNight
12%3123122219%49%
2047
March1st to 15thNight
13%4123212320%43%
2145
16th to endNight
7%4122122320%50%
2288
April1st to 15thNight
7%2132223322%47%
2142
16th to endNight
9%3122112321%49%
1810
May1st to 15thNight
7%3143122321%47%
1754
16th to endNight
321322325%24%46%
1827
June1st to 15thNight
2112222423%53%
1755
16th to endNight
2122122423%55%
1755
July1st to 15thNight
31221235%24%50%
1755
16th to endNight
2122222424%54%
1846
August1st to 15thNight
11211235%16%62%
1727
16th to endNight
331342335%18%50%
2043
September1st to 15thNight
9%31432345%13%49%
2145
16th to endNight
7%31331335%14%52%
2145
October1st to 15thNight
8%333223314%54%
2220
16th to endNight
9%2122112311%61%
2448
November1st to 15thNight
5%4133123217%53%
2322
16th to endNight
10%3122122319%50%
2535
December1st to 15thNight
12%5%132122319%44%
2535
16th to endNight
12%5%232122321%41%
2704

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%5%23212335%57%
1746
16th to endDay
12%31222333458%
1872
February1st to 15thDay
14%5%2432223453%
1856
16th to endDay
20%5%1331123452%
1710
March1st to 15thDay
17%423324436%48%
2145
16th to endDay
14%5%23423345%50%
2286
April1st to 15thDay
11%42332335%6%52%
2136
16th to endDay
12%41332335%6%51%
2420
May1st to 15thDay
12%5%24424446%48%
2526
16th to endDay
10%5%245%25%45%8%45%
2638
June1st to 15thDay
5%2134245%6%9%54%
2535
16th to endDay
6%223325%46%8%54%
2535
July1st to 15thDay
5%224436%47%8%49%
2535
16th to endDay
3113335%46%10%54%
2674
August1st to 15thDay
421233445%8%58%
2486
16th to endDay
6%313435%6%7%9%47%
2507
September1st to 15thDay
11%3144245%5%6%49%
2145
16th to endDay
10%31342335%6%54%
2145
October1st to 15thDay
12%323313336%56%
2054
16th to endDay
10%31221222466%
2033
November1st to 15thDay
10%313324336%57%
1863
16th to endDay
12%41222222463%
1755
December1st to 15thDay
15%6%1332323452%
1755
16th to endDay
17%5%23322435%48%
1872
January1st to 15thNight
10%313313335%59%
2522
16th to endNight
11%32221223461%
2704
February1st to 15thNight
12%5%23312325%56%
2337
16th to endNight
15%322312235%56%
2047
March1st to 15thNight
14%413423346%51%
2145
16th to endNight
10%5%23223246%55%
2288
April1st to 15thNight
8%324324448%53%
2142
16th to endNight
10%323322347%56%
1810
May1st to 15thNight
10%425%323347%53%
1754
16th to endNight
5%22433436%11%52%
1827
June1st to 15thNight
221222335%9%64%
1755
16th to endNight
311332335%10%61%
1755
July1st to 15thNight
42331445%12%56%
1755
16th to endNight
221332235%10%62%
1846
August1st to 15thNight
21221235%9%66%
1727
16th to endNight
431342445%11%54%
2043
September1st to 15thNight
10%42432345%6%52%
2145
16th to endNight
7%31332335%8%57%
2145
October1st to 15thNight
9%312322346%59%
2220
16th to endNight
10%31221223466%
2448
November1st to 15thNight
7%313313335%62%
2322
16th to endNight
12%31231233461%
2535
December1st to 15thNight
13%423223345%54%
2535
16th to endNight
15%6%23312246%50%
2704

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
31%27%22%28%7%
1747
16th to endDay
29%36%20%30%10%
1872
February1st to 15thDay
35%26%23%24%7%
1857
16th to endDay
37%25%20%22%11%
1710
March1st to 15thDay
37%37%20%21%9%
2145
16th to endDay
37%310%21%20%6%
2288
April1st to 15thDay
33%311%22%18%11%
2136
16th to endDay
33%38%22%24%6%
2420
May1st to 15thDay
38%49%20%19%7%
2526
16th to endDay
36%5%11%23%19%2
2642
June1st to 15thDay
25%6%14%29%21%2
2535
16th to endDay
26%5%12%28%21%5%
2535
July1st to 15thDay
28%6%16%30%16%1
2396
16th to endDay
21%5%18%32%20%1
2519
August1st to 15thDay
21%6%13%30%25%3
2472
16th to endDay
28%6%14%31%15%3
2507
September1st to 15thDay
33%6%11%23%18%6%
2145
16th to endDay
29%46%24%24%9%
2145
October1st to 15thDay
29%310%23%20%12%
2054
16th to endDay
23%26%20%28%17%
2033
November1st to 15thDay
30%28%23%26%9%
1863
16th to endDay
27%15%20%30%12%
1755
December1st to 15thDay
35%36%21%26%6%
1755
16th to endDay
38%26%21%23%7%
1872
January1st to 15thNight
28%26%19%30%12%
2522
16th to endNight
27%26%19%30%14%
2704
February1st to 15thNight
32%27%21%22%13%
2347
16th to endNight
32%18%20%22%13%
2047
March1st to 15thNight
34%37%18%23%13%
2145
16th to endNight
30%412%23%23%6%
2288
April1st to 15thNight
29%410%21%19%14%
2142
16th to endNight
27%410%22%25%10%
1810
May1st to 15thNight
32%312%19%22%9%
1755
16th to endNight
26%416%28%21%3
1829
June1st to 15thNight
17%414%34%23%5%
1755
16th to endNight
19%413%27%28%6%
1755
July1st to 15thNight
21%413%35%19%4
1665
16th to endNight
17%413%33%27%4
1738
August1st to 15thNight
13%411%30%32%7%
1717
16th to endNight
23%411%31%23%5%
2043
September1st to 15thNight
31%410%21%21%9%
2145
16th to endNight
25%38%24%26%11%
2145
October1st to 15thNight
25%211%25%19%15%
2220
16th to endNight
23%1418%29%21%
2448
November1st to 15thNight
25%37%25%24%14%
2322
16th to endNight
28%25%17%33%13%
2535
December1st to 15thNight
32%18%21%24%10%
2535
16th to endNight
36%27%21%23%9%
2704

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
17%8%33%28%11%
135
16th to endDay
10%6%39%27%12%2
144
February1st to 15thDay
10%7%42%28%11%
135
16th to endDay
29%10%37%17%5%
120
March1st to 15thDay
20%13%40%17%8%
135
16th to endDay
11%8%40%27%11%1
144
April1st to 15thDay
17%18%28%22%11%1
135
16th to endDay
14%7%38%25%12%1
432
May1st to 15thDay
15%7%31%32%10%2
543
16th to endDay
14%5%25%31%17%5%
597
June1st to 15thDay
7%10%42%30%8%
570
16th to endDay
6%18%35%36%12%
570
July1st to 15thDay
45%33%38%16%
550
16th to endDay
3419%46%25%
595
August1st to 15thDay
5%325%46%18%
549
16th to endDay
9%228%41%17%
419
September1st to 15thDay
10%211%40%35%
180
16th to endDay
15%5%18%40%21%
180
October1st to 15thDay
8%114%25%38%11%
180
16th to endDay
17%320%29%23%5%
178
November1st to 15thDay
19%221%29%21%5%
135
16th to endDay
16%8%33%25%13%2
135
December1st to 15thDay
23%325%31%9%5%
135
16th to endDay
18%11%34%29%6%
144
January1st to 15thNight
12%8%32%36%9%
975
16th to endNight
13%7%34%35%8%
1040
February1st to 15thNight
13%8%36%35%5%
819
16th to endNight
17%9%42%25%3
681
March1st to 15thNight
17%6%37%33%5%
585
16th to endNight
11%10%37%35%5%
624
April1st to 15thNight
9%10%43%29%6%
584
16th to endNight
12%5%39%33%8%
579
May1st to 15thNight
10%5%37%35%8%1
585
16th to endNight
6%229%39%19%2
611
June1st to 15thNight
3116%50%25%2
585
16th to endNight
412%46%32%4
585
July1st to 15thNight
5%7%44%37%5%
555
16th to endNight
2334%53%4
612
August1st to 15thNight
1238%51%5%
575
16th to endNight
6%339%43%7%
621
September1st to 15thNight
12%7%34%40%5%
585
16th to endNight
8%9%39%35%6%
582
October1st to 15thNight
10%218%39%26%2
660
16th to endNight
11%5%26%36%18%1
816
November1st to 15thNight
8%428%38%18%1
802
16th to endNight
14%7%32%33%12%
975
December1st to 15thNight
16%7%29%38%8%
975
16th to endNight
19%6%34%32%6%
1040
Page generated at 2018-10-28 07:41:01. Version ac04

Copyright 2018 A. Danko


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