Denison
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Denison clear sky chart from 2005-11-05 to 2017-04-09.

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
37%
15546
20%
45516
11%
15499
45%
15499
28%
28574

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
18%
2371
7%
895
36%
895
25%
1589
January16th to endNight
22%
960
19%
2496
5%
960
32%
960
22%
1774
February1st to 15thNight
23%
880
12%
2288
4%
876
28%
876
22%
1669
February16th to endNight
27%
723
21%
1985
6%
723
38%
723
28%
1288
March1st to 15thNight
35%
541
21%
1981
14%
541
45%
541
23%
1177
March16th to endNight
25%
576
15%
2112
10%
576
34%
576
17%
1414
April1st to 15thNight
29%
521
18%
1793
12%
521
41%
521
23%
1088
April16th to endNight
29%
495
18%
1496
11%
495
41%
495
21%
1030
May1st to 15thNight
35%
495
19%
1485
12%
495
43%
495
26%
953
May16th to endNight
42%
515
14%
1412
6%
513
48%
513
29%
910
June1st to 15thNight
49%
495
16%
1320
6%
495
52%
495
32%
844
June16th to endNight
57%
495
19%
1320
8%
495
60%
495
46%
733
July1st to 15thNight
65%
465
18%
1279
8%
465
68%
465
47%
694
July16th to endNight
76%
522
23%
1468
20%
489
77%
489
52%
726
August1st to 15thNight
63%
494
22%
1475
24%
491
66%
491
38%
831
August16th to endNight
61%
525
21%
1614
21%
525
65%
525
35%
939
September1st to 15thNight
56%
495
26%
1705
23%
495
66%
495
36%
902
September16th to endNight
48%
492
27%
1815
21%
492
59%
492
34%
926
October1st to 15thNight
38%
646
28%
1966
17%
646
48%
646
32%
1141
October16th to endNight
35%
704
22%
2112
11%
704
44%
704
29%
1270
November1st to 15thNight
35%
847
26%
2295
11%
847
46%
847
36%
1354
November16th to endNight
28%
900
20%
2520
9%
900
37%
900
28%
1602
December1st to 15thNight
24%
900
15%
2520
5%
900
32%
900
21%
1767
December16th to endNight
22%
960
17%
2688
7%
960
32%
960
18%
1953

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%35%5%2445%7%40%
45756
Night
11%6%35%424347%46%
45700
Cloud CoverDay
13%7%35%5%2445%7%40%
45767
Night
11%6%35%424347%46%
45704
Cloud CoverDay
13%7%36%43445%7%40%
45765
Night
11%7%35%424347%45%
45704
TransparencyDay
43%5%13%24%12%1
45459
Night
38%413%25%15%2
45516
SeeingDay
15%7%29%30%14%2
5271
Night
15%8%33%31%10%1
15546

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
8%9%47%7%4445%6%36%
1564
16th to endDay
11%12%6%8%7%23447%31%
1728
February1st to 15thDay
12%11%5%9%5%44346%31%
1575
16th to endDay
11%10%38%5%33446%36%
1498
March1st to 15thDay
12%9%47%5%24347%38%
1967
16th to endDay
17%12%46%424445%31%
2112
April1st to 15thDay
16%8%35%434446%38%
2017
16th to endDay
24%9%35%42435%5%32%
2133
May1st to 15thDay
18%7%35%5%35%5%5%6%33%
2136
16th to endDay
16%6%35%335%5%5%6%37%
2349
June1st to 15thDay
15%5%26%5%35%36%8%36%
2310
16th to endDay
6%3144245%6%9%49%
2310
July1st to 15thDay
8%424425%46%9%46%
2265
16th to endDay
5%213425%5%7%9%51%
2284
August1st to 15thDay
10%424436%6%5%9%42%
2145
16th to endDay
12%5%2442345%6%46%
2235
September1st to 15thDay
12%5%2432445%7%47%
1924
16th to endDay
10%31231345%8%55%
1815
October1st to 15thDay
14%423314236%51%
1653
16th to endDay
14%6%26%423345%45%
1760
November1st to 15thDay
8%6%15%5%24346%51%
1560
16th to endDay
13%9%36%41345%6%41%
1440
December1st to 15thDay
13%10%5%9%7%24436%31%
1440
16th to endDay
14%11%6%10%7%3445%6%26%
1536
January1st to 15thNight
8%7%47%6%35%45%7%40%
2371
16th to endNight
10%10%5%8%5%25%45%5%37%
2496
February1st to 15thNight
12%10%48%6%44345%34%
2285
16th to endNight
9%7%35%5%24446%45%
1985
March1st to 15thNight
12%7%34323347%47%
1969
16th to endNight
14%9%46%5%2435%7%35%
2112
April1st to 15thNight
14%7%2442435%6%45%
1793
16th to endNight
17%9%15%5%34346%37%
1496
May1st to 15thNight
15%5%2442335%8%43%
1485
16th to endNight
10%436%43445%7%46%
1410
June1st to 15thNight
9%425%4245%6%9%44%
1320
16th to endNight
321332446%9%58%
1320
July1st to 15thNight
42133235%5%9%58%
1362
16th to endNight
32122243410%61%
1576
August1st to 15thNight
6%425%42335%9%53%
1485
16th to endNight
10%31432436%5%53%
1614
September1st to 15thNight
9%41331335%7%55%
1705
16th to endNight
10%413223436%56%
1815
October1st to 15thNight
14%424213235%53%
1966
16th to endNight
16%6%24313235%51%
2112
November1st to 15thNight
8%424324346%54%
2295
16th to endNight
11%8%24424346%46%
2520
December1st to 15thNight
13%10%46%5%2445%6%35%
2520
16th to endNight
14%10%5%9%6%33346%32%
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
7%9%47%7%4445%7%36%
1564
16th to endDay
11%12%6%8%7%33447%31%
1728
February1st to 15thDay
12%11%5%9%5%44446%32%
1575
16th to endDay
11%10%38%6%34446%36%
1498
March1st to 15thDay
12%9%47%5%24346%38%
1978
16th to endDay
17%12%46%5%24445%31%
2112
April1st to 15thDay
16%8%35%434446%38%
2017
16th to endDay
24%9%35%42435%5%32%
2133
May1st to 15thDay
18%7%25%5%35%5%5%6%32%
2136
16th to endDay
16%6%35%425%5%6%6%37%
2349
June1st to 15thDay
15%5%26%5%35%35%8%36%
2310
16th to endDay
6%3244345%6%9%49%
2310
July1st to 15thDay
8%5%24425%46%9%47%
2265
16th to endDay
5%214435%5%7%8%51%
2284
August1st to 15thDay
10%4245%36%6%5%8%42%
2145
16th to endDay
12%5%1432345%7%46%
2235
September1st to 15thDay
12%5%2432445%7%47%
1924
16th to endDay
11%31232345%7%55%
1815
October1st to 15thDay
14%424413235%51%
1653
16th to endDay
14%7%26%423345%45%
1760
November1st to 15thDay
8%5%145%24346%51%
1560
16th to endDay
13%9%36%41345%6%41%
1440
December1st to 15thDay
13%10%5%9%7%24436%31%
1440
16th to endDay
14%11%6%10%7%3445%6%26%
1536
January1st to 15thNight
7%7%37%6%35%45%7%40%
2371
16th to endNight
10%10%48%5%3445%5%37%
2496
February1st to 15thNight
12%10%48%6%44346%34%
2278
16th to endNight
9%7%36%5%24446%45%
1985
March1st to 15thNight
12%8%25%323347%47%
1981
16th to endNight
15%9%46%5%2435%7%35%
2112
April1st to 15thNight
14%7%2442435%6%44%
1793
16th to endNight
18%9%25%5%34346%37%
1496
May1st to 15thNight
16%5%2442335%8%43%
1484
16th to endNight
10%435%43445%7%46%
1410
June1st to 15thNight
9%435%425%5%5%8%44%
1320
16th to endNight
3113325%47%9%58%
1320
July1st to 15thNight
42123235%5%8%59%
1362
16th to endNight
32122243410%61%
1576
August1st to 15thNight
6%42443335%9%53%
1485
16th to endNight
10%31432445%5%53%
1614
September1st to 15thNight
9%41331435%7%55%
1705
16th to endNight
11%413213346%56%
1815
October1st to 15thNight
14%424312245%53%
1966
16th to endNight
16%6%24213225%51%
2112
November1st to 15thNight
8%424324346%54%
2295
16th to endNight
11%8%34424346%46%
2520
December1st to 15thNight
13%11%36%5%2445%6%35%
2520
16th to endNight
14%10%5%8%7%33346%32%
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
8%9%48%7%445%47%36%
1564
16th to endDay
10%13%5%9%6%2345%7%30%
1728
February1st to 15thDay
12%12%5%9%6%35%346%31%
1575
16th to endDay
11%10%47%6%33447%36%
1498
March1st to 15thDay
12%9%47%5%2435%6%37%
1978
16th to endDay
17%12%46%5%2445%5%30%
2110
April1st to 15thDay
16%8%36%434446%38%
2017
16th to endDay
24%9%24423445%32%
2133
May1st to 15thDay
18%8%25%5%35%5%5%7%32%
2136
16th to endDay
16%6%25%425%5%5%7%37%
2349
June1st to 15thDay
15%6%26%5%35%46%8%36%
2310
16th to endDay
6%3234345%6%9%49%
2310
July1st to 15thDay
9%325%425%46%9%46%
2265
16th to endDay
5%214435%5%6%9%50%
2284
August1st to 15thDay
10%4245%36%5%6%8%42%
2145
16th to endDay
13%5%25%32345%7%46%
2235
September1st to 15thDay
12%5%2432436%7%47%
1924
16th to endDay
11%23313448%55%
1815
October1st to 15thDay
14%5%24413325%51%
1653
16th to endDay
14%7%26%324346%45%
1760
November1st to 15thDay
8%5%15%5%34347%50%
1560
16th to endDay
13%8%36%5%1345%6%41%
1440
December1st to 15thDay
13%10%5%9%7%34436%31%
1440
16th to endDay
14%11%6%10%6%345%46%25%
1536
January1st to 15thNight
8%8%37%6%3445%7%40%
2371
16th to endNight
9%11%48%5%35%45%5%37%
2496
February1st to 15thNight
13%9%5%7%6%34345%34%
2278
16th to endNight
9%7%45%6%3445%6%45%
1985
March1st to 15thNight
12%7%34423437%46%
1981
16th to endNight
14%11%45%5%3435%7%35%
2112
April1st to 15thNight
13%8%2432345%7%44%
1793
16th to endNight
17%9%35%5%33346%37%
1496
May1st to 15thNight
15%5%25%32345%8%43%
1484
16th to endNight
10%5%25%43445%7%45%
1410
June1st to 15thNight
8%5%26%5%25%46%8%44%
1320
16th to endNight
3213315%5%6%9%58%
1320
July1st to 15thNight
42133245%5%9%58%
1362
16th to endNight
311222435%10%61%
1576
August1st to 15thNight
6%42432335%8%54%
1485
16th to endNight
9%41432345%6%53%
1614
September1st to 15thNight
9%413314347%55%
1705
16th to endNight
10%5%3323346%56%
1815
October1st to 15thNight
14%5%33212245%53%
1966
16th to endNight
15%6%2431323451%
2112
November1st to 15thNight
8%434323346%54%
2295
16th to endNight
11%8%25%423446%46%
2520
December1st to 15thNight
13%10%47%5%24446%35%
2520
16th to endNight
14%10%5%8%7%23346%32%
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
47%316%20%11%
1565
16th to endDay
53%315%18%8%
1728
February1st to 15thDay
53%313%20%7%
1576
16th to endDay
48%6%12%19%10%2
1498
March1st to 15thDay
47%413%23%10%1
1978
16th to endDay
55%413%19%6%1
2112
April1st to 15thDay
48%411%25%8%1
2017
16th to endDay
53%410%20%9%
2133
May1st to 15thDay
50%6%13%21%8%
2136
16th to endDay
45%7%12%23%9%1
2353
June1st to 15thDay
45%5%15%21%10%
2310
16th to endDay
29%7%16%30%12%2
2310
July1st to 15thDay
35%5%15%26%12%4
2120
16th to endDay
27%6%16%29%17%1
2129
August1st to 15thDay
37%6%13%25%15%1
2131
16th to endDay
36%5%11%26%15%4
2235
September1st to 15thDay
36%411%27%17%2
1924
16th to endDay
27%415%31%20%1
1815
October1st to 15thDay
36%38%28%20%1
1653
16th to endDay
41%311%26%15%1
1760
November1st to 15thDay
34%313%24%22%1
1560
16th to endDay
43%314%26%11%
1440
December1st to 15thDay
55%413%18%6%1
1440
16th to endDay
59%412%16%6%1
1536
January1st to 15thNight
43%415%22%14%
2371
16th to endNight
48%414%22%9%
2496
February1st to 15thNight
52%312%22%8%1
2288
16th to endNight
40%413%24%15%2
1985
March1st to 15thNight
38%5%12%28%13%2
1981
16th to endNight
49%412%23%7%1
2112
April1st to 15thNight
39%411%27%15%1
1793
16th to endNight
48%412%21%11%1
1496
May1st to 15thNight
39%6%13%25%14%1
1485
16th to endNight
38%6%17%22%12%2
1412
June1st to 15thNight
36%6%14%27%13%1
1320
16th to endNight
21%6%14%31%21%4
1320
July1st to 15thNight
22%5%20%30%15%4
1279
16th to endNight
18%5%16%36%21%2
1468
August1st to 15thNight
29%5%13%30%19%2
1475
16th to endNight
30%6%12%22%18%8%
1614
September1st to 15thNight
29%411%28%23%3
1705
16th to endNight
29%310%33%20%2
1815
October1st to 15thNight
34%38%27%22%3
1966
16th to endNight
37%313%26%17%1
2112
November1st to 15thNight
30%313%25%23%2
2295
16th to endNight
38%414%27%13%1
2520
December1st to 15thNight
49%413%24%8%
2520
16th to endNight
53%412%20%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
15%12%45%23%3
90
16th to endDay
26%5%40%21%42
96
February1st to 15thDay
17%17%40%21%3
90
16th to endDay
22%9%28%30%7%1
81
March1st to 15thDay
15%17%46%16%3
90
16th to endDay
33%11%32%18%4
96
April1st to 15thDay
17%11%41%23%41
188
16th to endDay
32%10%27%20%7%1
363
May1st to 15thDay
23%14%28%22%8%1
393
16th to endDay
18%6%34%25%13%2
437
June1st to 15thDay
15%7%28%32%14%1
420
16th to endDay
46%31%34%18%4
420
July1st to 15thDay
10%425%33%20%6%
400
16th to endDay
4121%44%23%4
445
August1st to 15thDay
8%120%41%23%3
418
16th to endDay
16%318%33%23%5%
403
September1st to 15thDay
7%429%34%20%4
199
16th to endDay
27%32%33%22%2
90
October1st to 15thDay
12%5%35%27%14%4
90
16th to endDay
10%9%43%31%5%
96
November1st to 15thDay
411%32%36%11%4
90
16th to endDay
34%11%32%16%5%
90
December1st to 15thDay
17%23%37%16%31
90
16th to endDay
29%21%36%10%2
96
January1st to 15thNight
12%14%39%27%5%
900
16th to endNight
17%11%40%25%5%
960
February1st to 15thNight
17%8%42%26%5%
880
16th to endNight
13%10%43%23%7%
723
March1st to 15thNight
17%10%33%28%9%1
541
16th to endNight
22%9%36%25%5%
576
April1st to 15thNight
19%11%35%28%4
521
16th to endNight
23%9%31%25%9%
495
May1st to 15thNight
17%9%34%29%8%
495
16th to endNight
11%5%34%36%12%
515
June1st to 15thNight
11%429%43%11%
495
16th to endNight
4331%44%15%
495
July1st to 15thNight
6%123%43%23%1
465
16th to endNight
4112%53%26%1
522
August1st to 15thNight
8%218%43%24%2
494
16th to endNight
11%218%41%21%4
525
September1st to 15thNight
11%223%36%21%3
495
16th to endNight
13%430%31%16%2
492
October1st to 15thNight
17%7%33%29%9%2
646
16th to endNight
20%7%30%30%9%
704
November1st to 15thNight
11%11%38%27%10%
847
16th to endNight
17%13%37%24%7%
900
December1st to 15thNight
19%10%39%26%4
900
16th to endNight
20%10%36%25%6%
960
Page generated at 2017-04-10 08:00:35. Version ac04

Copyright 2017 A. Danko


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