Kansas State University
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kansas State University clear sky chart from 2005-11-05 to 2017-09-21.

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
43%
15917
23%
47036
14%
15872
52%
15872
33%
27565

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
34%
900
23%
2327
9%
895
45%
895
35%
1443
January16th to endNight
34%
960
27%
2496
11%
960
43%
960
36%
1517
February1st to 15thNight
30%
879
16%
2288
6%
875
37%
875
25%
1594
February16th to endNight
30%
635
25%
1897
8%
635
44%
635
30%
1130
March1st to 15thNight
36%
561
22%
2001
13%
561
47%
561
28%
1127
March16th to endNight
29%
576
18%
2112
11%
576
39%
576
20%
1317
April1st to 15thNight
30%
539
19%
1902
12%
539
44%
539
27%
1057
April16th to endNight
32%
540
22%
1620
15%
540
45%
540
24%
1044
May1st to 15thNight
36%
540
18%
1620
13%
540
44%
540
24%
1054
May16th to endNight
47%
561
18%
1684
13%
561
53%
561
32%
1023
June1st to 15thNight
55%
540
19%
1620
11%
540
60%
540
37%
907
June16th to endNight
59%
540
22%
1620
14%
540
65%
540
49%
811
July1st to 15thNight
66%
510
18%
1530
14%
510
69%
510
42%
814
July16th to endNight
69%
564
24%
1594
24%
531
71%
531
41%
862
August1st to 15thNight
71%
539
23%
1610
25%
536
75%
536
42%
877
August16th to endNight
70%
573
28%
1751
29%
573
75%
573
42%
935
September1st to 15thNight
58%
540
24%
1947
23%
540
66%
540
33%
1050
September16th to endNight
58%
510
30%
1881
25%
510
68%
510
34%
967
October1st to 15thNight
43%
604
28%
1924
20%
604
50%
604
30%
1122
October16th to endNight
42%
704
30%
2112
15%
704
53%
704
41%
1114
November1st to 15thNight
44%
842
30%
2242
14%
842
56%
842
44%
1232
November16th to endNight
38%
900
28%
2340
11%
900
49%
900
39%
1371
December1st to 15thNight
34%
900
21%
2422
8%
900
43%
900
30%
1552
December16th to endNight
34%
960
25%
2496
11%
960
43%
960
30%
1645

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
10%5%2442445%7%47%
47797
Night
9%5%2432345%7%51%
47232
Cloud CoverDay
10%5%2442445%7%47%
47795
Night
9%5%2432345%6%51%
47232
TransparencyDay
35%6%12%26%16%2
47495
Night
32%5%12%26%18%3
47037
SeeingDay
12%7%27%31%16%3
5923
Night
12%7%31%35%11%
15920

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
9%5%25%424347%49%
1611
16th to endDay
9%7%45%42335%6%47%
1728
February1st to 15thDay
11%9%47%424446%40%
1581
16th to endDay
8%8%35%43345%6%46%
1580
March1st to 15thDay
11%7%35%5%34447%42%
1959
16th to endDay
18%7%25%5%24346%39%
2112
April1st to 15thDay
14%7%25%42435%5%44%
2041
16th to endDay
17%7%345%34445%38%
2340
May1st to 15thDay
14%6%35%5%2445%7%39%
2331
16th to endDay
13%5%25%5%3446%7%39%
2430
June1st to 15thDay
9%4145%24446%50%
2340
16th to endDay
5%2133246%5%10%54%
2340
July1st to 15thDay
8%325%425%47%9%46%
2340
16th to endDay
6%314435%5%6%9%49%
2466
August1st to 15thDay
6%4244245%5%11%49%
2340
16th to endDay
8%32342445%7%53%
2450
September1st to 15thDay
11%5%15%423446%49%
2010
16th to endDay
7%42342345%6%54%
1871
October1st to 15thDay
12%423323335%55%
1694
16th to endDay
10%413323335%57%
1760
November1st to 15thDay
7%31222435%6%60%
1613
16th to endDay
11%7%13213346%54%
1620
December1st to 15thDay
13%6%26%5%25%35%6%41%
1512
16th to endDay
12%8%47%5%13437%40%
1728
January1st to 15thNight
8%6%24333446%51%
2327
16th to endNight
8%5%24424345%53%
2496
February1st to 15thNight
9%9%35%5%35%446%41%
2278
16th to endNight
8%7%245%24447%49%
1897
March1st to 15thNight
9%5%2432445%6%50%
2001
16th to endNight
16%7%25%423346%42%
2112
April1st to 15thNight
11%5%23423346%50%
1902
16th to endNight
17%7%1442345%6%42%
1620
May1st to 15thNight
15%5%35%4245%46%42%
1619
16th to endNight
11%324325%45%8%48%
1683
June1st to 15thNight
5%21333445%9%55%
1620
16th to endNight
41113245%6%9%60%
1620
July1st to 15thNight
5%222325%46%10%55%
1620
16th to endNight
422442346%9%54%
1702
August1st to 15thNight
341442446%9%54%
1620
16th to endNight
5%314223446%59%
1751
September1st to 15thNight
8%324323448%52%
1947
16th to endNight
6%324423446%57%
1881
October1st to 15thNight
13%424423345%52%
1924
16th to endNight
10%413222235%61%
2112
November1st to 15thNight
7%413312345%62%
2242
16th to endNight
10%5%12222346%57%
2340
December1st to 15thNight
10%7%35%323346%47%
2422
16th to endNight
13%9%24323346%45%
2496

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
9%5%25%424447%49%
1611
16th to endDay
9%7%35%42345%5%47%
1728
February1st to 15thDay
11%9%37%434446%40%
1581
16th to endDay
8%8%35%33345%7%46%
1580
March1st to 15thDay
11%8%35%4345%47%42%
1959
16th to endDay
18%9%26%423446%38%
2110
April1st to 15thDay
14%7%25%424345%44%
2041
16th to endDay
17%7%35%434436%37%
2340
May1st to 15thDay
14%6%36%4245%5%6%39%
2331
16th to endDay
14%5%25%5%3446%7%39%
2430
June1st to 15thDay
8%5%245%34447%50%
2340
16th to endDay
42134245%6%10%54%
2340
July1st to 15thDay
8%315%425%5%7%9%46%
2340
16th to endDay
6%314425%5%7%9%49%
2466
August1st to 15thDay
6%32343446%10%49%
2340
16th to endDay
8%32433445%7%53%
2450
September1st to 15thDay
11%424423446%49%
2010
16th to endDay
8%423323448%53%
1871
October1st to 15thDay
12%5%23323336%54%
1694
16th to endDay
10%413422335%57%
1760
November1st to 15thDay
7%213224347%60%
1613
16th to endDay
12%5%23213236%54%
1620
December1st to 15thDay
13%7%26%6%2435%6%41%
1512
16th to endDay
12%8%5%7%5%13437%39%
1728
January1st to 15thNight
7%6%25%433446%51%
2327
16th to endNight
8%6%24424346%53%
2496
February1st to 15thNight
10%8%36%5%34446%40%
2278
16th to endNight
8%6%24434446%49%
1897
March1st to 15thNight
9%6%25%32345%6%49%
2001
16th to endNight
17%6%25%423346%41%
2112
April1st to 15thNight
11%5%24323447%50%
1902
16th to endNight
17%6%2442445%6%42%
1620
May1st to 15thNight
16%5%25%424446%42%
1619
16th to endNight
11%3234235%5%8%48%
1683
June1st to 15thNight
5%21433436%9%55%
1620
16th to endNight
4123145%6%9%60%
1620
July1st to 15thNight
5%222325%45%10%54%
1620
16th to endNight
431442446%8%54%
1702
August1st to 15thNight
33134335%7%9%54%
1620
16th to endNight
5%323224346%59%
1751
September1st to 15thNight
9%32432345%7%52%
1947
16th to endNight
7%32442345%5%57%
1881
October1st to 15thNight
13%424323345%52%
1924
16th to endNight
9%413212335%60%
2112
November1st to 15thNight
7%413323345%61%
2242
16th to endNight
10%5%1331225%5%57%
2340
December1st to 15thNight
10%6%36%324446%47%
2422
16th to endNight
13%9%3432345%5%45%
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
35%414%29%14%2
1612
16th to endDay
37%5%15%26%13%1
1728
February1st to 15thDay
43%5%15%22%9%2
1582
16th to endDay
37%5%12%26%15%2
1580
March1st to 15thDay
41%412%23%15%2
1959
16th to endDay
47%5%11%22%10%2
2112
April1st to 15thDay
40%5%12%23%17%1
2041
16th to endDay
46%6%10%23%12%
2340
May1st to 15thDay
44%6%10%23%13%1
2331
16th to endDay
41%8%14%22%10%1
2434
June1st to 15thDay
33%6%13%28%15%2
2340
16th to endDay
24%6%15%30%20%2
2340
July1st to 15thDay
31%7%12%28%16%3
2201
16th to endDay
27%7%13%31%17%3
2311
August1st to 15thDay
28%8%15%27%17%2
2326
16th to endDay
30%6%11%26%18%6%
2450
September1st to 15thDay
34%6%11%23%17%6%
2010
16th to endDay
29%6%11%29%21%2
1871
October1st to 15thDay
31%49%24%24%3
1694
16th to endDay
30%310%28%22%4
1760
November1st to 15thDay
24%5%12%26%26%5%
1613
16th to endDay
32%410%31%19%1
1620
December1st to 15thDay
42%5%14%25%11%
1512
16th to endDay
44%414%23%12%1
1728
January1st to 15thNight
33%415%25%18%1
2327
16th to endNight
32%416%26%17%3
2496
February1st to 15thNight
43%6%12%24%10%2
2288
16th to endNight
35%412%25%18%4
1897
March1st to 15thNight
33%5%13%23%18%5%
2001
16th to endNight
43%413%22%13%3
2112
April1st to 15thNight
33%413%23%22%2
1902
16th to endNight
40%5%10%24%16%1
1620
May1st to 15thNight
41%6%11%21%17%1
1620
16th to endNight
32%7%20%22%14%1
1685
June1st to 15thNight
25%8%14%30%17%4
1620
16th to endNight
18%7%14%34%21%4
1620
July1st to 15thNight
23%6%14%30%19%4
1530
16th to endNight
26%412%31%21%2
1594
August1st to 15thNight
23%7%17%30%16%3
1610
16th to endNight
25%5%9%28%24%6%
1751
September1st to 15thNight
30%5%12%26%16%8%
1947
16th to endNight
28%5%9%26%26%4
1881
October1st to 15thNight
35%48%22%23%5%
1924
16th to endNight
26%39%30%25%5%
2112
November1st to 15thNight
24%311%26%25%8%
2242
16th to endNight
28%311%31%20%3
2340
December1st to 15thNight
37%413%28%14%
2422
16th to endNight
40%415%22%15%2
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
17%12%48%15%5%
90
16th to endDay
15%9%42%26%6%
96
February1st to 15thDay
12%20%42%18%6%
90
16th to endDay
12%14%44%16%11%1
81
March1st to 15thDay
21%13%43%21%1
90
16th to endDay
23%12%44%17%1
96
April1st to 15thDay
20%11%32%27%8%
160
16th to endDay
22%14%35%18%7%1
450
May1st to 15thDay
17%13%29%24%12%1
468
16th to endDay
17%10%30%27%11%2
517
June1st to 15thDay
9%428%36%17%3
495
16th to endDay
5%5%33%35%16%3
495
July1st to 15thDay
11%219%39%22%4
475
16th to endDay
6%113%43%30%4
515
August1st to 15thDay
6%116%41%29%3
493
16th to endDay
10%218%35%25%6%
490
September1st to 15thDay
10%320%40%21%3
165
16th to endDay
9%5%23%40%16%3
105
October1st to 15thDay
7%11%32%31%10%7%
90
16th to endDay
5%10%38%30%13%2
96
November1st to 15thDay
7%8%23%37%16%5%
90
16th to endDay
31%16%34%12%41
90
December1st to 15thDay
13%17%46%13%5%3
90
16th to endDay
19%15%37%23%3
96
January1st to 15thNight
12%11%36%31%7%
900
16th to endNight
11%9%39%32%5%
960
February1st to 15thNight
15%9%38%33%3
880
16th to endNight
12%13%39%29%5%
635
March1st to 15thNight
14%9%36%32%6%
561
16th to endNight
18%12%36%25%5%
576
April1st to 15thNight
14%12%38%28%5%
539
16th to endNight
20%11%32%28%5%
540
May1st to 15thNight
17%8%30%32%10%1
540
16th to endNight
14%430%35%13%1
563
June1st to 15thNight
7%329%41%18%
540
16th to endNight
4230%45%16%
540
July1st to 15thNight
7%19%50%20%1
510
16th to endNight
5%15%49%25%2
564
August1st to 15thNight
5%14%52%26%1
539
16th to endNight
7%115%40%30%4
573
September1st to 15thNight
10%223%37%23%2
540
16th to endNight
8%324%39%21%1
510
October1st to 15thNight
14%5%29%32%15%1
604
16th to endNight
11%8%35%31%11%
704
November1st to 15thNight
9%10%32%35%10%
842
16th to endNight
13%11%34%31%8%
900
December1st to 15thNight
14%11%35%32%6%
900
16th to endNight
18%9%32%33%5%
960
Page generated at 2017-09-22 06:35:34. Version ac04

Copyright 2017 A. Danko


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