Astronomy Club of Akron Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Astronomy Club of Akron Observatory clear sky chart from 2005-11-05 to 2018-03-11.

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%
15954
14%
49222
11%
15916
42%
15916
19%
34943

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
15%
776
8%
2522
4%
776
20%
776
9%
2041
January16th to endNight
16%
832
9%
2704
4%
832
23%
832
10%
2139
February1st to 15thNight
17%
763
8%
2482
4%
761
23%
761
9%
1988
February16th to endNight
19%
683
10%
2071
4%
683
24%
683
11%
1647
March1st to 15thNight
26%
764
15%
2135
9%
764
31%
764
17%
1601
March16th to endNight
30%
768
15%
2112
10%
768
34%
768
21%
1527
April1st to 15thNight
27%
691
12%
1868
6%
691
32%
691
19%
1379
April16th to endNight
37%
540
19%
1620
9%
540
45%
540
25%
1077
May1st to 15thNight
43%
540
13%
1620
9%
540
47%
540
19%
1159
May16th to endNight
57%
561
15%
1684
14%
561
59%
561
28%
1080
June1st to 15thNight
55%
363
16%
1443
18%
363
61%
363
25%
846
June16th to endNight
54%
393
15%
1473
17%
393
59%
393
23%
896
July1st to 15thNight
65%
510
14%
1530
15%
510
67%
510
32%
963
July16th to endNight
67%
564
16%
1595
15%
531
69%
531
33%
958
August1st to 15thNight
66%
539
21%
1609
17%
536
67%
536
32%
964
August16th to endNight
66%
590
22%
1736
18%
590
68%
590
35%
1052
September1st to 15thNight
61%
720
24%
1926
16%
720
64%
720
34%
1216
September16th to endNight
58%
717
25%
1980
21%
717
60%
717
31%
1254
October1st to 15thNight
47%
720
18%
2118
16%
720
51%
720
26%
1406
October16th to endNight
32%
768
16%
2304
13%
768
38%
768
18%
1655
November1st to 15thNight
39%
760
19%
2468
16%
760
45%
760
22%
1630
November16th to endNight
23%
780
12%
2664
9%
780
29%
780
13%
1968
December1st to 15thNight
18%
780
7%
2730
4%
780
22%
780
9%
2175
December16th to endNight
14%
832
6%
2828
3%
832
19%
832
8%
2322

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
16%9%47%6%3445%7%30%
49385
Night
16%9%46%5%3445%6%33%
49415
Cloud CoverDay
16%9%47%6%3445%7%30%
49395
Night
15%10%46%5%3445%6%33%
49419
TransparencyDay
52%6%11%18%9%1
49096
Night
50%6%11%18%11%1
49222
SeeingDay
19%9%24%22%15%7%
5890
Night
20%8%27%28%13%1
15961

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
21%14%7%9%8%4433418%
1746
16th to endDay
17%19%7%11%8%24445%14%
1872
February1st to 15thDay
18%16%6%11%9%3334417%
1710
16th to endDay
16%14%6%9%7%33446%22%
1688
March1st to 15thDay
20%13%7%7%5%3335%5%25%
2050
16th to endDay
19%10%47%5%34445%29%
2112
April1st to 15thDay
19%9%46%5%34446%30%
2090
16th to endDay
18%9%36%5%34435%36%
2340
May1st to 15thDay
18%8%37%5%46%6%5%6%29%
2331
16th to endDay
12%5%25%6%35%5%7%8%37%
2431
June1st to 15thDay
13%6%25%5%35%5%6%8%36%
2514
16th to endDay
12%5%25%5%35%6%6%10%35%
2482
July1st to 15thDay
12%5%37%5%45%6%6%8%35%
2340
16th to endDay
11%5%25%5%36%6%7%10%35%
2465
August1st to 15thDay
8%6%26%6%46%7%6%9%34%
2340
16th to endDay
9%5%26%6%36%6%6%9%36%
2453
September1st to 15thDay
14%5%35%5%3346%7%39%
2033
16th to endDay
17%6%25%4335%46%39%
1980
October1st to 15thDay
17%7%36%6%2335%7%35%
1842
16th to endDay
23%8%26%5%24345%33%
1920
November1st to 15thDay
14%10%25%6%44446%36%
1719
16th to endDay
18%14%5%8%5%2445%6%23%
1624
December1st to 15thDay
21%16%7%12%6%3333318%
1560
16th to endDay
20%19%6%12%7%33325%13%
1743
January1st to 15thNight
21%16%6%9%7%3434419%
2522
16th to endNight
17%16%6%9%7%35%445%20%
2704
February1st to 15thNight
19%14%5%9%7%35%33421%
2480
16th to endNight
18%14%5%9%7%34445%22%
2071
March1st to 15thNight
19%11%5%7%5%24345%29%
2123
16th to endNight
15%9%46%5%34446%33%
2112
April1st to 15thNight
17%12%45%5%2445%6%30%
1868
16th to endNight
12%7%36%5%3445%7%39%
1620
May1st to 15thNight
15%7%46%5%5%5%46%7%32%
1620
16th to endNight
10%5%36%43445%8%42%
1682
June1st to 15thNight
7%5%35%5%35%46%7%44%
1443
16th to endNight
11%5%24426%5%5%10%40%
1473
July1st to 15thNight
8%425%5%26%46%9%44%
1620
16th to endNight
6%425%43446%9%47%
1703
August1st to 15thNight
7%4235%35%46%9%46%
1620
16th to endNight
8%5%145%245%5%6%49%
1736
September1st to 15thNight
12%414424347%49%
1926
16th to endNight
12%5%25%325%447%46%
1980
October1st to 15thNight
16%5%35%5%2445%6%40%
2118
16th to endNight
21%7%35%6%3445%5%32%
2304
November1st to 15thNight
16%7%2443446%7%38%
2468
16th to endNight
19%12%47%5%34346%26%
2664
December1st to 15thNight
22%15%6%8%42434422%
2730
16th to endNight
21%15%6%8%6%34446%17%
2828

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
21%15%7%9%8%4443417%
1746
16th to endDay
16%19%7%11%8%2445%414%
1872
February1st to 15thDay
18%16%7%11%8%3334417%
1710
16th to endDay
17%14%6%9%7%24445%22%
1688
March1st to 15thDay
20%13%6%7%5%34245%24%
2061
16th to endDay
19%10%47%5%34445%29%
2111
April1st to 15thDay
19%9%46%5%34447%30%
2090
16th to endDay
17%8%37%434445%35%
2340
May1st to 15thDay
18%8%36%6%45%5%5%6%28%
2331
16th to endDay
11%6%25%5%35%5%6%9%37%
2431
June1st to 15thDay
13%6%26%5%35%5%6%9%36%
2514
16th to endDay
12%5%25%5%35%6%6%10%34%
2482
July1st to 15thDay
12%6%36%6%35%5%6%8%34%
2340
16th to endDay
10%5%25%5%46%6%7%10%35%
2465
August1st to 15thDay
8%6%26%6%46%7%6%10%33%
2340
16th to endDay
9%6%27%5%46%7%6%8%36%
2453
September1st to 15thDay
14%6%35%5%245%5%7%39%
2033
16th to endDay
17%6%25%424447%39%
1980
October1st to 15thDay
17%7%36%6%2435%8%35%
1842
16th to endDay
22%9%35%5%23345%32%
1920
November1st to 15thDay
14%10%35%6%3445%6%36%
1719
16th to endDay
18%14%6%8%5%2435%5%23%
1624
December1st to 15thDay
21%16%7%12%7%2343318%
1560
16th to endDay
21%18%6%12%7%33335%13%
1743
January1st to 15thNight
20%16%6%9%7%3434420%
2522
16th to endNight
17%16%5%9%7%35%445%20%
2704
February1st to 15thNight
18%15%6%9%6%45%34421%
2473
16th to endNight
18%14%5%9%7%35%44422%
2071
March1st to 15thNight
19%12%47%5%2435%5%29%
2135
16th to endNight
16%8%47%6%2445%6%33%
2112
April1st to 15thNight
17%11%45%5%3345%6%30%
1868
16th to endNight
12%8%26%6%2445%6%39%
1620
May1st to 15thNight
15%7%35%6%45%46%7%32%
1619
16th to endNight
9%6%36%425%45%8%42%
1682
June1st to 15thNight
6%6%346%35%5%6%7%45%
1443
16th to endNight
10%5%25%425%6%5%10%40%
1473
July1st to 15thNight
7%5%25%5%35%46%9%44%
1620
16th to endNight
5%425%5%35%46%9%46%
1703
August1st to 15thNight
7%4235%35%5%6%9%46%
1620
16th to endNight
8%5%144245%5%6%49%
1736
September1st to 15thNight
12%5%14423347%49%
1926
16th to endNight
12%5%25%325%35%7%46%
1980
October1st to 15thNight
15%5%345%34446%41%
2118
16th to endNight
20%7%36%5%3445%6%32%
2304
November1st to 15thNight
16%8%2443446%7%38%
2468
16th to endNight
19%12%47%6%3435%6%26%
2664
December1st to 15thNight
21%16%6%8%5%24345%21%
2730
16th to endNight
21%15%6%8%6%34347%17%
2828

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
70%410%9%4
1747
16th to endDay
71%5%11%8%2
1872
February1st to 15thDay
70%47%11%4
1712
16th to endDay
62%5%11%13%6%
1688
March1st to 15thDay
61%410%16%5%
2061
16th to endDay
55%5%10%18%9%
2112
April1st to 15thDay
53%5%12%16%10%
2090
16th to endDay
50%5%10%18%12%3
2340
May1st to 15thDay
53%7%10%17%9%1
2331
16th to endDay
41%8%14%21%11%1
2435
June1st to 15thDay
42%7%12%24%11%
2514
16th to endDay
41%9%13%20%13%1
2482
July1st to 15thDay
45%7%10%20%14%1
2201
16th to endDay
39%9%15%21%11%1
2310
August1st to 15thDay
41%9%14%22%10%1
2327
16th to endDay
41%7%12%23%11%3
2453
September1st to 15thDay
42%6%12%21%13%2
2033
16th to endDay
44%5%9%21%17%1
1980
October1st to 15thDay
47%5%11%19%14%1
1842
16th to endDay
53%414%18%8%
1920
November1st to 15thDay
48%410%20%11%3
1719
16th to endDay
61%5%10%14%6%
1624
December1st to 15thDay
70%5%8%11%3
1560
16th to endDay
74%49%8%2
1743
January1st to 15thNight
68%49%11%5%
2522
16th to endNight
65%412%12%4
2704
February1st to 15thNight
65%5%10%12%5%
2482
16th to endNight
64%5%9%15%6%
2071
March1st to 15thNight
56%5%9%19%8%1
2135
16th to endNight
50%5%12%19%9%2
2112
April1st to 15thNight
53%5%10%16%13%
1868
16th to endNight
43%5%12%17%16%4
1620
May1st to 15thNight
49%7%10%19%11%1
1620
16th to endNight
38%7%14%22%14%2
1684
June1st to 15thNight
36%7%13%24%16%1
1443
16th to endNight
37%8%15%20%15%1
1473
July1st to 15thNight
35%6%12%23%18%2
1530
16th to endNight
32%7%15%25%15%3
1595
August1st to 15thNight
31%8%12%28%18%1
1609
16th to endNight
32%6%13%25%16%5%
1736
September1st to 15thNight
35%5%11%24%19%3
1926
16th to endNight
37%5%9%25%21%1
1980
October1st to 15thNight
42%6%12%19%18%1
2118
16th to endNight
51%5%11%21%8%
2304
November1st to 15thNight
44%6%12%19%13%4
2468
16th to endNight
57%411%17%7%
2664
December1st to 15thNight
65%5%11%11%5%
2730
16th to endNight
67%6%13%10%1
2828

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
24%23%34%10%6%
135
16th to endDay
30%22%31%12%2
144
February1st to 15thDay
29%25%37%6%
135
16th to endDay
28%24%39%8%
120
March1st to 15thDay
25%15%28%22%7%
277
16th to endDay
24%14%28%21%7%2
288
April1st to 15thDay
25%13%26%21%10%1
270
16th to endDay
21%8%31%18%11%8%
270
May1st to 15thDay
24%9%30%18%13%3
288
16th to endDay
17%5%27%27%12%8%
331
June1st to 15thDay
14%6%22%33%16%6%
315
16th to endDay
18%6%20%31%15%8%
315
July1st to 15thDay
16%220%27%21%10%
305
16th to endDay
10%215%26%29%16%
326
August1st to 15thDay
16%16%23%28%14%
313
16th to endDay
11%314%23%27%19%
332
September1st to 15thDay
15%415%23%21%19%
315
16th to endDay
18%5%12%17%27%18%
314
October1st to 15thDay
15%7%23%25%23%4
315
16th to endDay
23%11%33%21%8%1
336
November1st to 15thDay
24%13%21%21%16%2
137
16th to endDay
22%25%35%12%3
104
December1st to 15thDay
18%27%30%14%5%3
90
16th to endDay
28%26%33%8%1
115
January1st to 15thNight
27%16%33%17%4
780
16th to endNight
25%16%35%19%2
832
February1st to 15thNight
25%16%33%21%2
764
16th to endNight
26%12%37%21%3
683
March1st to 15thNight
24%12%32%24%5%
764
16th to endNight
20%9%34%25%9%1
768
April1st to 15thNight
22%11%34%24%6%
691
16th to endNight
15%6%35%28%12%1
540
May1st to 15thNight
20%5%25%36%11%1
540
16th to endNight
14%218%39%21%4
563
June1st to 15thNight
8%127%42%19%
363
16th to endNight
11%223%43%18%
393
July1st to 15thNight
10%114%44%27%2
510
16th to endNight
7%115%40%31%4
564
August1st to 15thNight
10%13%41%29%4
539
16th to endNight
10%114%32%35%4
590
September1st to 15thNight
15%214%33%28%5%
720
16th to endNight
14%316%30%28%7%
717
October1st to 15thNight
18%423%31%18%2
720
16th to endNight
25%10%28%27%8%
768
November1st to 15thNight
21%8%26%30%12%1
760
16th to endNight
25%15%31%18%9%
780
December1st to 15thNight
29%14%31%19%5%
780
16th to endNight
26%14%36%19%2
832
Page generated at 2018-03-12 13:28:05. Version ac04

Copyright 2018 A. Danko


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