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 2017-08-12.

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%
15363
17%
46345
13%
15323
48%
15323
23%
31313

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
18%
719
12%
2327
6%
716
25%
716
10%
1839
January16th to endNight
24%
768
13%
2496
9%
768
30%
768
13%
1884
February1st to 15thNight
25%
701
12%
2238
6%
701
32%
701
15%
1632
February16th to endNight
23%
631
13%
1893
7%
631
29%
631
14%
1426
March1st to 15thNight
32%
720
16%
2049
11%
720
37%
720
20%
1457
March16th to endNight
33%
768
17%
2112
10%
768
38%
768
23%
1485
April1st to 15thNight
32%
636
15%
1864
8%
636
39%
636
24%
1260
April16th to endNight
41%
540
21%
1620
9%
540
51%
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
60%
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
20%
1595
17%
531
77%
531
38%
917
August1st to 15thNight
71%
527
21%
1575
18%
524
73%
524
36%
935
August16th to endNight
74%
525
24%
1602
22%
525
75%
525
40%
887
September1st to 15thNight
65%
643
28%
1798
22%
643
68%
643
39%
1049
September16th to endNight
59%
657
27%
1815
22%
657
63%
657
35%
1115
October1st to 15thNight
54%
660
25%
1897
23%
660
58%
660
32%
1162
October16th to endNight
37%
704
21%
2148
17%
704
44%
704
23%
1443
November1st to 15thNight
47%
700
24%
2276
21%
700
53%
700
29%
1354
November16th to endNight
33%
720
16%
2340
12%
720
40%
720
18%
1636
December1st to 15thNight
26%
720
10%
2340
7%
720
29%
720
12%
1812
December16th to endNight
21%
768
10%
2496
6%
768
27%
768
10%
1997

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%345%5%7%33%
47603
Night
15%8%36%5%3445%6%37%
46536
Cloud CoverDay
16%8%36%5%3445%7%33%
47613
Night
15%8%36%5%3445%6%37%
46540
TransparencyDay
48%411%20%11%1
47313
Night
46%411%21%13%2
46345
SeeingDay
17%5%21%23%19%11%
5392
Night
18%6%23%32%16%1
15368

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%2443418%
1611
16th to endDay
16%17%7%9%6%45%45%6%17%
1728
February1st to 15thDay
18%14%5%9%6%3445%5%23%
1621
16th to endDay
17%14%5%8%5%34446%25%
1580
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
7%425%6%46%6%8%10%38%
2288
16th to endDay
7%425%5%35%6%7%10%41%
2245
September1st to 15thDay
12%5%244236%5%7%45%
1821
16th to endDay
16%5%345%2445%5%43%
1815
October1st to 15thDay
14%5%345%345%5%6%42%
1732
16th to endDay
21%8%25%5%24346%37%
1724
November1st to 15thDay
11%7%25%5%23446%45%
1582
16th to endDay
19%11%5%6%6%24436%30%
1620
December1st to 15thDay
25%15%6%8%5%2324419%
1620
16th to endDay
23%15%7%7%6%23445%17%
1728
January1st to 15thNight
22%12%5%10%6%4333421%
2327
16th to endNight
17%14%6%7%6%34445%25%
2496
February1st to 15thNight
20%11%47%5%33345%29%
2236
16th to endNight
17%13%6%9%6%34445%25%
1893
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%435%6%7%8%46%
1586
16th to endNight
6%3145%2345%8%53%
1602
September1st to 15thNight
11%413314346%54%
1798
16th to endNight
14%423323448%47%
1815
October1st to 15thNight
12%5%2442335%6%48%
1897
16th to endNight
19%7%25%5%24346%38%
2148
November1st to 15thNight
14%5%23423345%47%
2276
16th to endNight
19%9%46%5%24446%30%
2340
December1st to 15thNight
24%12%48%5%33345%23%
2340
16th to endNight
23%15%6%8%6%33445%19%
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
24%12%6%10%7%2343418%
1611
16th to endDay
16%17%7%9%6%44445%18%
1728
February1st to 15thDay
18%14%5%9%6%33445%23%
1621
16th to endDay
17%14%5%8%5%34446%25%
1580
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
7%425%6%45%6%8%10%38%
2288
16th to endDay
7%425%435%6%7%10%41%
2245
September1st to 15thDay
12%5%244245%5%6%46%
1821
16th to endDay
16%5%345%2445%5%43%
1815
October1st to 15thDay
14%5%25%5%25%446%42%
1732
16th to endDay
21%7%25%424336%36%
1724
November1st to 15thDay
12%7%25%5%24446%45%
1582
16th to endDay
19%11%46%5%34346%30%
1620
December1st to 15thDay
25%15%7%8%5%3334419%
1620
16th to endDay
23%16%6%7%6%23445%17%
1728
January1st to 15thNight
23%12%5%10%6%4333421%
2327
16th to endNight
17%14%5%7%6%34445%25%
2496
February1st to 15thNight
20%10%47%5%33346%29%
2229
16th to endNight
17%13%5%8%6%34445%25%
1893
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%315%445%6%7%9%46%
1586
16th to endNight
6%31443345%8%53%
1602
September1st to 15thNight
11%423313346%54%
1798
16th to endNight
14%423323448%47%
1815
October1st to 15thNight
12%5%2442335%6%47%
1897
16th to endNight
19%7%35%5%24345%39%
2148
November1st to 15thNight
15%5%23423345%47%
2276
16th to endNight
19%9%46%5%24446%30%
2340
December1st to 15thNight
24%13%47%5%34335%23%
2340
16th to endNight
23%15%5%8%6%33435%19%
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
69%37%13%5%
1612
16th to endDay
66%314%12%3
1728
February1st to 15thDay
61%411%14%7%
1623
16th to endDay
59%411%18%4
1580
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
36%6%13%25%15%2
2275
16th to endDay
34%6%13%26%14%4
2245
September1st to 15thDay
35%5%9%22%23%2
1821
16th to endDay
42%48%20%24%1
1815
October1st to 15thDay
42%49%23%19%1
1732
16th to endDay
48%212%24%10%1
1724
November1st to 15thDay
39%48%26%16%4
1582
16th to endDay
55%311%19%9%
1620
December1st to 15thDay
68%29%14%4
1620
16th to endDay
67%410%13%3
1728
January1st to 15thNight
66%28%14%7%
2327
16th to endNight
60%311%17%6%
2496
February1st to 15thNight
57%312%18%7%1
2238
16th to endNight
60%29%20%6%
1893
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
1575
16th to endNight
28%413%28%20%4
1602
September1st to 15thNight
29%412%21%25%5%
1798
16th to endNight
35%37%23%28%
1815
October1st to 15thNight
36%49%26%19%2
1897
16th to endNight
47%38%26%12%1
2148
November1st to 15thNight
38%210%23%19%4
2276
16th to endNight
53%210%21%10%
2340
December1st to 15thNight
63%310%15%6%
2340
16th to endNight
67%310%14%3
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
27%14%38%8%6%3
90
16th to endDay
31%18%31%14%4
96
February1st to 15thDay
22%22%40%15%
90
16th to endDay
20%8%44%19%6%
81
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%20%32%24%
297
16th to endDay
9%8%19%32%29%
268
September1st to 15thDay
12%16%18%37%22%
255
16th to endDay
20%111%18%28%18%
254
October1st to 15thDay
11%420%30%22%9%
255
16th to endDay
21%8%26%26%16%1
236
November1st to 15thDay
14%7%15%23%26%12%
90
16th to endDay
26%10%37%18%42
90
December1st to 15thDay
30%12%33%16%34
90
16th to endDay
28%13%42%15%
96
January1st to 15thNight
27%11%33%22%4
720
16th to endNight
23%10%32%28%3
768
February1st to 15thNight
25%8%31%31%3
704
16th to endNight
23%11%32%29%3
631
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
7%110%39%36%5%
527
16th to endNight
8%17%36%40%5%
525
September1st to 15thNight
14%210%32%33%6%
643
16th to endNight
16%314%28%33%3
657
October1st to 15thNight
14%419%35%21%3
660
16th to endNight
21%6%28%32%10%
704
November1st to 15thNight
18%6%23%33%17%1
700
16th to endNight
24%10%26%28%10%
720
December1st to 15thNight
29%6%28%27%6%
720
16th to endNight
30%9%28%27%4
768
Page generated at 2017-08-13 14:16:31. Version ac04

Copyright 2017 A. Danko


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