Columbus
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Columbus clear sky chart from 2005-11-05 to 2018-02-22.

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%
16122
17%
48693
13%
16082
48%
16082
23%
32893

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
20%
779
12%
2522
7%
776
27%
776
11%
1980
January16th to endNight
23%
832
13%
2704
8%
832
30%
832
13%
2036
February1st to 15thNight
25%
761
11%
2428
6%
761
31%
761
14%
1791
February16th to endNight
23%
659
13%
1977
7%
659
28%
659
14%
1494
March1st to 15thNight
32%
720
16%
2049
11%
720
36%
720
20%
1457
March16th to endNight
32%
768
17%
2112
10%
768
38%
768
23%
1485
April1st to 15thNight
32%
636
15%
1864
8%
636
38%
636
24%
1260
April16th to endNight
40%
540
21%
1620
9%
540
50%
540
27%
1051
May1st to 15thNight
40%
540
14%
1620
9%
540
45%
540
21%
1132
May16th to endNight
59%
562
17%
1684
14%
561
62%
561
32%
1053
June1st to 15thNight
65%
540
16%
1620
14%
540
69%
540
37%
935
June16th to endNight
61%
540
17%
1486
13%
540
65%
540
34%
927
July1st to 15thNight
65%
510
15%
1454
14%
510
67%
510
32%
925
July16th to endNight
74%
564
19%
1595
16%
531
76%
531
38%
917
August1st to 15thNight
72%
539
21%
1609
18%
536
74%
536
36%
954
August16th to endNight
74%
573
25%
1749
23%
573
76%
573
40%
969
September1st to 15thNight
64%
702
26%
1962
20%
702
67%
702
38%
1159
September16th to endNight
60%
717
29%
1980
24%
717
63%
717
36%
1200
October1st to 15thNight
54%
720
24%
2070
22%
720
58%
720
31%
1277
October16th to endNight
38%
768
23%
2343
19%
768
45%
768
24%
1559
November1st to 15thNight
46%
760
23%
2471
19%
760
52%
760
28%
1489
November16th to endNight
33%
780
18%
2535
13%
780
41%
780
19%
1746
December1st to 15thNight
26%
780
9%
2535
7%
780
30%
780
13%
1940
December16th to endNight
21%
832
10%
2704
6%
832
27%
832
10%
2157

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
15%8%36%5%3445%7%33%
49533
Night
15%8%36%5%3445%6%37%
48884
Cloud CoverDay
16%8%36%5%3445%7%33%
49543
Night
15%8%36%5%3445%6%37%
48888
TransparencyDay
48%411%20%11%1
49243
Night
46%411%21%13%2
48693
SeeingDay
18%5%21%23%19%10%
6052
Night
18%6%23%32%16%1
16127

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
24%12%6%10%6%3444418%
1746
16th to endDay
16%17%7%9%6%45%35%5%19%
1872
February1st to 15thDay
19%14%5%9%7%34345%22%
1760
16th to endDay
18%14%5%8%5%34446%24%
1643
March1st to 15thDay
21%11%5%6%6%34436%25%
1898
16th to endDay
22%8%46%5%23336%31%
2112
April1st to 15thDay
20%9%35%424345%35%
2093
16th to endDay
18%5%25%6%345%5%6%36%
2340
May1st to 15thDay
19%8%36%5%35%45%6%31%
2331
16th to endDay
11%5%25%6%35%5%7%9%37%
2431
June1st to 15thDay
11%425%6%36%5%5%9%38%
2340
16th to endDay
10%425%6%35%6%7%9%36%
2466
July1st to 15thDay
12%6%36%6%36%6%5%8%35%
2412
16th to endDay
8%4245%46%7%7%10%38%
2465
August1st to 15thDay
6%425%6%45%6%8%10%38%
2340
16th to endDay
7%425%5%35%6%7%10%41%
2450
September1st to 15thDay
12%5%244235%5%7%44%
1986
16th to endDay
14%6%245%2435%5%44%
1980
October1st to 15thDay
14%6%245%345%5%6%41%
1889
16th to endDay
20%7%25%5%24345%37%
1880
November1st to 15thDay
12%7%25%5%23446%43%
1717
16th to endDay
18%11%46%5%24436%31%
1755
December1st to 15thDay
24%14%6%8%6%33345%20%
1755
16th to endDay
23%15%6%8%6%24445%18%
1872
January1st to 15thNight
22%12%5%10%7%43335%21%
2522
16th to endNight
17%14%5%7%6%35%445%26%
2704
February1st to 15thNight
21%11%47%5%33345%29%
2426
16th to endNight
18%13%6%8%6%34445%24%
1977
March1st to 15thNight
17%10%37%5%35%35%5%32%
2037
16th to endNight
17%9%36%5%2345%7%34%
2112
April1st to 15thNight
16%7%36%5%3446%6%36%
1864
16th to endNight
13%6%25%5%3445%7%40%
1620
May1st to 15thNight
17%6%27%6%35%5%5%6%33%
1620
16th to endNight
10%5%245%25%5%6%10%41%
1682
June1st to 15thNight
5%3145%25%6%5%9%49%
1620
16th to endNight
8%425%335%5%6%10%43%
1486
July1st to 15thNight
8%5%245%45%6%5%7%45%
1542
16th to endNight
6%3244346%5%9%49%
1703
August1st to 15thNight
6%325%445%6%7%8%46%
1620
16th to endNight
6%3145%2446%8%52%
1749
September1st to 15thNight
12%413314346%53%
1962
16th to endNight
13%423323347%49%
1980
October1st to 15thNight
12%5%2442335%6%46%
2070
16th to endNight
18%7%25%5%24346%39%
2343
November1st to 15thNight
15%6%23423346%46%
2471
16th to endNight
19%9%45%5%245%46%32%
2535
December1st to 15thNight
22%12%48%5%34345%24%
2535
16th to endNight
22%15%6%8%6%33445%19%
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
24%12%6%10%7%3444418%
1746
16th to endDay
16%18%6%9%6%44445%19%
1872
February1st to 15thDay
19%14%5%9%7%33445%22%
1760
16th to endDay
18%13%5%8%5%34446%24%
1643
March1st to 15thDay
22%11%5%6%6%34436%26%
1909
16th to endDay
22%9%37%5%23336%31%
2111
April1st to 15thDay
20%8%45%424445%35%
2093
16th to endDay
18%5%26%5%345%46%36%
2340
May1st to 15thDay
19%8%35%5%35%45%6%31%
2331
16th to endDay
11%5%25%6%35%5%7%8%37%
2431
June1st to 15thDay
11%425%6%37%5%5%9%38%
2340
16th to endDay
10%425%6%36%5%7%9%36%
2466
July1st to 15thDay
12%6%36%6%36%5%5%8%36%
2412
16th to endDay
9%4145%45%7%7%10%38%
2465
August1st to 15thDay
6%425%6%45%6%8%10%38%
2340
16th to endDay
7%425%436%5%7%10%41%
2450
September1st to 15thDay
12%5%2442445%7%45%
1986
16th to endDay
15%5%345%23445%44%
1980
October1st to 15thDay
14%6%25%5%25%5%46%41%
1889
16th to endDay
20%7%25%424346%37%
1880
November1st to 15thDay
13%7%25%5%24446%43%
1717
16th to endDay
18%11%46%5%34346%31%
1755
December1st to 15thDay
24%14%6%8%5%33345%20%
1755
16th to endDay
23%16%6%7%6%23445%18%
1872
January1st to 15thNight
22%11%5%10%6%43345%21%
2522
16th to endNight
17%14%5%7%7%35%445%26%
2704
February1st to 15thNight
21%11%47%5%33345%29%
2419
16th to endNight
18%13%5%8%6%34445%25%
1977
March1st to 15thNight
18%9%37%5%34446%32%
2049
16th to endNight
17%9%46%5%2445%7%34%
2112
April1st to 15thNight
17%7%26%5%3445%6%36%
1864
16th to endNight
13%6%25%5%3445%7%40%
1620
May1st to 15thNight
17%6%26%5%45%45%6%33%
1619
16th to endNight
10%5%245%345%7%10%41%
1682
June1st to 15thNight
6%3245%25%6%5%9%49%
1620
16th to endNight
9%434425%5%7%9%43%
1486
July1st to 15thNight
9%425%445%5%5%7%45%
1542
16th to endNight
6%2244346%5%9%49%
1703
August1st to 15thNight
6%325%445%6%7%8%46%
1620
16th to endNight
6%3145%3346%8%52%
1749
September1st to 15thNight
12%423313347%53%
1962
16th to endNight
13%423323447%49%
1980
October1st to 15thNight
12%5%245%2435%6%46%
2070
16th to endNight
18%7%35%5%24346%39%
2343
November1st to 15thNight
15%5%23423346%46%
2471
16th to endNight
19%9%46%5%24446%32%
2535
December1st to 15thNight
23%12%48%5%34435%24%
2535
16th to endNight
22%15%5%8%6%34445%19%
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
69%37%13%5%
1747
16th to endDay
65%214%13%3
1872
February1st to 15thDay
63%410%14%7%
1762
16th to endDay
60%411%18%4
1643
March1st to 15thDay
58%413%17%4
1909
16th to endDay
54%310%23%6%
2112
April1st to 15thDay
50%312%21%10%1
2093
16th to endDay
47%410%20%13%4
2340
May1st to 15thDay
52%412%19%8%1
2331
16th to endDay
41%6%13%24%12%1
2435
June1st to 15thDay
40%5%13%23%16%1
2340
16th to endDay
40%6%15%19%15%2
2466
July1st to 15thDay
45%6%9%19%16%2
2272
16th to endDay
36%7%15%27%11%1
2310
August1st to 15thDay
35%6%13%26%15%2
2327
16th to endDay
34%6%13%25%15%4
2450
September1st to 15thDay
37%5%9%22%22%2
1986
16th to endDay
41%48%20%24%1
1980
October1st to 15thDay
42%410%22%19%1
1889
16th to endDay
47%212%25%10%1
1880
November1st to 15thDay
41%48%25%15%4
1717
16th to endDay
53%312%20%9%
1755
December1st to 15thDay
67%29%15%4
1755
16th to endDay
67%410%13%3
1872
January1st to 15thNight
65%38%14%7%
2522
16th to endNight
60%311%17%6%
2704
February1st to 15thNight
58%311%17%7%
2428
16th to endNight
61%210%19%6%
1977
March1st to 15thNight
52%211%23%7%2
2049
16th to endNight
49%411%24%10%1
2112
April1st to 15thNight
46%312%19%15%1
1864
16th to endNight
42%310%19%18%5%
1620
May1st to 15thNight
49%5%12%22%9%1
1620
16th to endNight
35%6%14%25%13%3
1684
June1st to 15thNight
29%6%16%24%20%2
1620
16th to endNight
33%7%16%21%18%3
1486
July1st to 15thNight
37%5%9%21%21%3
1454
16th to endNight
29%6%15%30%16%2
1595
August1st to 15thNight
31%5%15%24%20%1
1609
16th to endNight
27%5%13%27%21%4
1749
September1st to 15thNight
31%411%22%24%5%
1962
16th to endNight
34%37%24%29%1
1980
October1st to 15thNight
37%49%25%20%2
2070
16th to endNight
46%38%26%13%1
2343
November1st to 15thNight
39%310%23%18%4
2471
16th to endNight
52%210%23%10%
2535
December1st to 15thNight
62%310%16%6%
2535
16th to endNight
66%410%15%3
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
27%9%40%13%7%2
135
16th to endDay
31%15%35%13%4
144
February1st to 15thDay
30%17%36%15%
135
16th to endDay
28%9%39%19%5%
100
March1st to 15thDay
27%9%27%27%8%
199
16th to endDay
24%8%33%23%9%
288
April1st to 15thDay
24%10%25%25%12%2
270
16th to endDay
19%8%23%27%12%8%
270
May1st to 15thDay
25%6%24%21%15%6%
288
16th to endDay
16%423%28%15%12%
331
June1st to 15thDay
10%216%31%26%12%
315
16th to endDay
15%422%27%21%8%
441
July1st to 15thDay
17%315%26%23%13%
376
16th to endDay
9%18%20%31%28%
326
August1st to 15thDay
9%111%21%32%23%
313
16th to endDay
8%9%22%34%24%
332
September1st to 15thDay
15%29%20%32%20%
315
16th to endDay
16%112%18%29%21%
314
October1st to 15thDay
13%320%28%24%9%
315
16th to endDay
21%7%27%23%16%2
296
November1st to 15thDay
21%6%20%22%21%8%
135
16th to endDay
24%8%34%23%6%1
135
December1st to 15thDay
22%14%37%15%6%3
135
16th to endDay
29%13%39%16%
144
January1st to 15thNight
26%10%32%24%5%
780
16th to endNight
23%10%34%28%3
832
February1st to 15thNight
26%8%31%30%2
764
16th to endNight
24%10%32%29%2
659
March1st to 15thNight
22%8%30%30%7%
720
16th to endNight
21%7%30%28%10%
768
April1st to 15thNight
19%8%35%27%8%
636
16th to endNight
17%5%32%30%12%1
540
May1st to 15thNight
17%7%25%34%14%
540
16th to endNight
11%317%36%27%3
563
June1st to 15thNight
6%217%47%24%1
540
16th to endNight
9%217%41%26%2
540
July1st to 15thNight
12%210%42%26%4
510
16th to endNight
6%18%39%39%4
564
August1st to 15thNight
6%19%39%36%5%
539
16th to endNight
8%16%37%40%5%
573
September1st to 15thNight
15%111%32%32%6%
702
16th to endNight
15%314%26%35%4
717
October1st to 15thNight
14%418%34%22%4
720
16th to endNight
21%6%27%31%11%
768
November1st to 15thNight
19%5%24%33%16%1
760
16th to endNight
23%9%27%28%10%
780
December1st to 15thNight
27%6%29%28%6%
780
16th to endNight
30%9%29%27%4
832
Page generated at 2018-02-23 11:21:39. Version ac04

Copyright 2018 A. Danko


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