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 2017-12-04.

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%
16353
20%
47905
11%
16306
45%
16306
28%
29909

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
29%
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%
539
18%
1853
11%
539
40%
539
23%
1128
April16th to endNight
29%
540
18%
1632
11%
540
41%
540
21%
1125
May1st to 15thNight
38%
540
18%
1620
12%
540
46%
540
28%
1014
May16th to endNight
42%
563
15%
1544
6%
561
48%
561
29%
999
June1st to 15thNight
51%
540
16%
1440
6%
540
54%
540
34%
903
June16th to endNight
55%
540
21%
1440
8%
540
59%
540
47%
793
July1st to 15thNight
66%
510
17%
1403
8%
510
69%
510
49%
751
July16th to endNight
76%
564
25%
1594
22%
531
77%
531
52%
786
August1st to 15thNight
64%
539
21%
1610
23%
536
66%
536
38%
900
August16th to endNight
61%
573
23%
1762
23%
573
66%
573
36%
1019
September1st to 15thNight
57%
540
25%
1860
23%
540
66%
540
37%
965
September16th to endNight
47%
537
28%
1980
21%
537
59%
537
34%
1013
October1st to 15thNight
37%
705
26%
2145
16%
705
46%
705
30%
1276
October16th to endNight
35%
768
24%
2304
12%
768
45%
768
30%
1374
November1st to 15thNight
34%
920
25%
2492
11%
920
44%
920
34%
1500
November16th to endNight
29%
975
22%
2730
10%
975
39%
975
30%
1699
December1st to 15thNight
25%
920
14%
2575
5%
920
33%
920
22%
1800
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
12%7%35%5%2445%7%41%
48579
Night
11%6%35%424347%46%
48089
Cloud CoverDay
12%7%35%5%2445%7%41%
48590
Night
11%6%25%424347%46%
48093
Cloud CoverDay
12%7%36%43445%7%40%
48588
Night
10%6%35%424347%46%
48093
TransparencyDay
42%5%13%24%12%1
48282
Night
38%413%26%15%2
47905
SeeingDay
14%7%29%29%14%3
6264
Night
14%8%33%31%10%1
16353

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
17%8%36%434446%38%
2094
16th to endDay
24%9%35%42335%5%31%
2327
May1st to 15thDay
17%7%245%35%5%5%6%35%
2331
16th to endDay
16%6%35%335%5%6%6%37%
2569
June1st to 15thDay
14%5%25%435%36%8%39%
2520
16th to endDay
6%3144245%6%9%49%
2520
July1st to 15thDay
8%423425%46%8%48%
2471
16th to endDay
5%213425%5%6%9%51%
2466
August1st to 15thDay
10%4245%36%6%5%9%42%
2340
16th to endDay
12%5%244235%6%6%47%
2439
September1st to 15thDay
11%42432445%6%49%
2099
16th to endDay
11%31232345%8%54%
1980
October1st to 15thDay
16%5%24414236%48%
1803
16th to endDay
13%7%26%423345%46%
1920
November1st to 15thDay
8%6%15%5%24346%50%
1693
16th to endDay
12%8%36%41345%6%43%
1560
December1st to 15thDay
13%9%5%9%7%24436%32%
1467
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
13%7%2442435%7%44%
1853
16th to endNight
18%9%25%5%33346%36%
1632
May1st to 15thNight
15%5%2442335%8%45%
1620
16th to endNight
11%426%43435%7%45%
1542
June1st to 15thNight
9%425%4245%6%8%46%
1440
16th to endNight
321232446%9%58%
1440
July1st to 15thNight
32133225%5%8%60%
1486
16th to endNight
32122244410%61%
1702
August1st to 15thNight
5%325%42335%9%53%
1620
16th to endNight
9%31432435%6%53%
1762
September1st to 15thNight
9%41331335%7%57%
1860
16th to endNight
10%413223446%56%
1980
October1st to 15thNight
15%5%24313245%51%
2145
16th to endNight
14%6%24313235%52%
2304
November1st to 15thNight
9%424324346%52%
2492
16th to endNight
10%8%24423346%48%
2730
December1st to 15thNight
13%10%36%5%2445%6%36%
2575
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
17%8%36%434446%37%
2094
16th to endDay
25%9%35%42435%5%31%
2327
May1st to 15thDay
17%7%25%5%35%5%5%6%35%
2331
16th to endDay
16%6%35%425%5%6%6%37%
2569
June1st to 15thDay
14%5%25%5%35%35%9%39%
2520
16th to endDay
6%3244345%6%9%49%
2520
July1st to 15thDay
8%424425%46%8%49%
2471
16th to endDay
5%213435%5%7%8%51%
2466
August1st to 15thDay
10%3245%36%6%5%9%42%
2340
16th to endDay
12%5%1442345%7%47%
2439
September1st to 15thDay
11%41432445%6%49%
2099
16th to endDay
11%31232345%7%55%
1980
October1st to 15thDay
16%424413235%48%
1803
16th to endDay
13%7%26%423345%45%
1920
November1st to 15thDay
8%6%15%5%24346%50%
1693
16th to endDay
12%8%36%41345%6%43%
1560
December1st to 15thDay
13%9%5%9%7%24436%32%
1467
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
13%7%2442435%7%44%
1853
16th to endNight
18%9%25%5%34346%36%
1632
May1st to 15thNight
15%42441335%8%45%
1619
16th to endNight
11%425%434447%45%
1542
June1st to 15thNight
9%425%4245%6%8%46%
1440
16th to endNight
311232447%9%58%
1440
July1st to 15thNight
32123235%48%60%
1486
16th to endNight
32122244410%61%
1702
August1st to 15thNight
5%32443335%9%53%
1620
16th to endNight
9%31442445%6%53%
1762
September1st to 15thNight
9%41231335%7%57%
1860
16th to endNight
10%413223346%56%
1980
October1st to 15thNight
15%424313245%51%
2145
16th to endNight
15%6%14313235%52%
2304
November1st to 15thNight
9%5%24324346%52%
2492
16th to endNight
10%7%34424346%48%
2730
December1st to 15thNight
12%10%36%5%2445%6%36%
2575
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%37%
2094
16th to endDay
24%9%25%5%23445%31%
2327
May1st to 15thDay
17%7%25%435%5%5%6%35%
2331
16th to endDay
16%6%25%425%5%5%7%37%
2569
June1st to 15thDay
14%5%25%435%46%8%39%
2520
16th to endDay
5%3244346%6%9%49%
2520
July1st to 15thDay
8%324425%46%9%48%
2471
16th to endDay
5%214435%5%6%9%51%
2466
August1st to 15thDay
9%4245%46%5%6%8%42%
2340
16th to endDay
12%5%2442445%7%46%
2439
September1st to 15thDay
11%5%2432436%7%49%
2099
16th to endDay
11%313313448%54%
1980
October1st to 15thDay
15%5%24413335%49%
1803
16th to endDay
14%7%26%324335%45%
1920
November1st to 15thDay
9%5%15%5%24347%49%
1693
16th to endDay
12%8%36%5%1335%6%42%
1560
December1st to 15thDay
13%10%5%9%7%34436%32%
1467
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%25%42345%7%43%
1853
16th to endNight
17%9%35%5%34347%36%
1632
May1st to 15thNight
15%425%31345%8%45%
1619
16th to endNight
11%5%25%435%45%7%45%
1542
June1st to 15thNight
8%425%5%25%46%8%46%
1440
16th to endNight
32133245%6%9%58%
1440
July1st to 15thNight
32133235%5%9%60%
1486
16th to endNight
311222435%10%61%
1702
August1st to 15thNight
5%32442435%8%54%
1620
16th to endNight
9%31432345%6%53%
1762
September1st to 15thNight
8%413313347%56%
1860
16th to endNight
10%5%3323346%56%
1980
October1st to 15thNight
15%5%34213345%51%
2145
16th to endNight
14%6%2431323452%
2304
November1st to 15thNight
9%434324346%52%
2492
16th to endNight
10%8%24423446%48%
2730
December1st to 15thNight
12%10%47%5%24446%36%
2575
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
2094
16th to endDay
54%410%20%9%
2327
May1st to 15thDay
48%6%13%22%10%
2331
16th to endDay
45%6%12%23%10%1
2573
June1st to 15thDay
42%5%14%23%12%1
2520
16th to endDay
29%6%16%30%13%2
2520
July1st to 15thDay
33%5%15%28%12%4
2326
16th to endDay
27%6%16%29%17%2
2311
August1st to 15thDay
37%6%14%25%14%1
2326
16th to endDay
35%5%11%26%16%3
2439
September1st to 15thDay
34%412%29%16%1
2099
16th to endDay
28%414%32%19%
1980
October1st to 15thDay
39%38%27%19%1
1803
16th to endDay
41%311%25%15%2
1920
November1st to 15thDay
35%314%24%21%1
1693
16th to endDay
41%313%26%12%
1560
December1st to 15thDay
54%413%19%6%1
1467
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
40%411%27%15%1
1853
16th to endNight
48%412%21%11%1
1632
May1st to 15thNight
37%6%13%26%15%1
1620
16th to endNight
38%6%16%22%13%2
1544
June1st to 15thNight
34%6%14%27%14%2
1440
16th to endNight
21%7%14%30%21%4
1440
July1st to 15thNight
21%5%20%31%16%4
1403
16th to endNight
18%5%15%36%21%2
1594
August1st to 15thNight
28%5%14%30%19%2
1610
16th to endNight
30%6%13%22%19%7%
1762
September1st to 15thNight
27%311%30%22%3
1860
16th to endNight
29%310%34%19%2
1980
October1st to 15thNight
36%38%26%21%3
2145
16th to endNight
36%313%25%19%1
2304
November1st to 15thNight
32%313%24%22%2
2492
16th to endNight
36%414%29%13%1
2730
December1st to 15thNight
48%413%24%9%
2575
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
18%11%40%23%4
213
16th to endDay
32%10%28%18%8%1
437
May1st to 15thDay
21%12%28%24%10%1
468
16th to endDay
18%6%35%24%12%2
517
June1st to 15thDay
13%7%27%32%17%1
495
16th to endDay
48%35%32%15%3
495
July1st to 15thDay
8%325%34%20%7%
475
16th to endDay
5%121%43%23%4
515
August1st to 15thDay
8%120%40%24%4
493
16th to endDay
14%319%32%23%6%
479
September1st to 15thDay
5%329%35%19%5%
254
16th to endDay
8%7%33%32%16%1
135
October1st to 15thDay
19%6%34%25%10%4
135
16th to endDay
15%10%40%27%5%
144
November1st to 15thDay
8%14%38%28%8%2
135
16th to endDay
25%14%34%19%5%
135
December1st to 15thDay
16%22%37%21%31
100
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
18%11%36%28%4
539
16th to endNight
23%9%32%25%9%
540
May1st to 15thNight
17%8%33%31%9%
540
16th to endNight
12%5%34%36%11%
563
June1st to 15thNight
10%428%42%12%
540
16th to endNight
4332%44%13%
540
July1st to 15thNight
5%122%44%23%1
510
16th to endNight
4113%52%26%1
564
August1st to 15thNight
8%219%43%24%2
539
16th to endNight
10%219%40%22%4
573
September1st to 15thNight
11%223%36%21%4
540
16th to endNight
13%431%32%15%2
537
October1st to 15thNight
18%7%33%29%9%1
705
16th to endNight
19%9%31%29%9%
768
November1st to 15thNight
12%11%38%26%9%
920
16th to endNight
16%13%38%24%7%
975
December1st to 15thNight
19%10%38%26%4
920
16th to endNight
20%10%36%25%6%
960
Page generated at 2017-12-05 09:19:03. Version ac04

Copyright 2017 A. Danko


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