Perrysburg Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Perrysburg Observatory clear sky chart from 2005-11-05 to 2017-12-20.

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%
16171
15%
47921
10%
16130
43%
16130
21%
33405

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
16%
899
11%
2506
4%
895
22%
895
13%
1957
January16th to endNight
17%
812
9%
2540
3%
812
23%
812
11%
2020
February1st to 15thNight
19%
701
9%
2241
4%
701
26%
701
11%
1712
February16th to endNight
24%
631
13%
1893
6%
631
32%
631
14%
1421
March1st to 15thNight
28%
720
13%
2076
8%
720
32%
720
17%
1538
March16th to endNight
31%
768
17%
2112
11%
768
37%
768
21%
1499
April1st to 15thNight
27%
593
13%
1827
7%
593
34%
593
18%
1270
April16th to endNight
36%
540
19%
1620
7%
540
45%
540
24%
1089
May1st to 15thNight
38%
540
13%
1620
7%
540
44%
540
18%
1198
May16th to endNight
49%
562
16%
1684
12%
561
54%
561
28%
1076
June1st to 15thNight
53%
540
15%
1482
10%
540
58%
540
30%
974
June16th to endNight
55%
540
17%
1440
12%
540
60%
540
32%
931
July1st to 15thNight
62%
510
16%
1360
13%
510
64%
510
36%
828
July16th to endNight
70%
564
18%
1534
16%
531
73%
531
40%
878
August1st to 15thNight
69%
539
20%
1609
16%
536
71%
536
35%
952
August16th to endNight
65%
573
22%
1756
18%
573
68%
573
33%
1040
September1st to 15thNight
58%
672
24%
1932
19%
672
62%
672
34%
1159
September16th to endNight
59%
717
26%
1980
20%
717
62%
717
34%
1208
October1st to 15thNight
48%
720
20%
2061
17%
720
52%
720
27%
1337
October16th to endNight
28%
768
18%
2394
13%
768
36%
768
19%
1637
November1st to 15thNight
36%
760
20%
2471
16%
760
44%
760
23%
1596
November16th to endNight
25%
780
15%
2535
10%
780
31%
780
14%
1855
December1st to 15thNight
21%
780
9%
2535
4%
780
26%
780
12%
1956
December16th to endNight
16%
942
7%
2713
2%
942
21%
942
9%
2274

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
14%8%36%6%35%5%5%7%33%
48912
Night
15%8%36%5%3445%6%36%
48102
Cloud CoverDay
14%8%36%6%35%5%5%7%33%
48922
Night
15%8%36%5%3445%6%36%
48106
TransparencyDay
49%7%12%19%11%1
48612
Night
47%6%12%20%12%1
47921
SeeingDay
17%8%26%24%15%7%
6130
Night
19%8%28%28%13%1
16176

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
20%15%5%8%6%45%336%19%
1432
16th to endDay
16%18%8%9%8%45%5%35%16%
1682
February1st to 15thDay
15%13%5%10%7%5%5%445%21%
1618
16th to endDay
15%12%5%10%8%345%5%5%23%
1580
March1st to 15thDay
19%12%5%8%6%2445%425%
1873
16th to endDay
20%11%47%6%33345%28%
2112
April1st to 15thDay
17%9%46%7%35%5%46%29%
2131
16th to endDay
17%6%35%5%23446%38%
2340
May1st to 15thDay
17%7%36%6%35%5%6%7%29%
2331
16th to endDay
12%5%35%5%35%6%5%8%38%
2431
June1st to 15thDay
11%6%25%5%35%5%5%8%40%
2475
16th to endDay
11%5%25%6%47%5%7%9%34%
2520
July1st to 15thDay
8%425%6%35%5%6%9%42%
2520
16th to endDay
8%4245%37%7%6%9%40%
2525
August1st to 15thDay
7%425%6%46%6%7%9%40%
2340
16th to endDay
10%425%5%35%5%7%10%38%
2444
September1st to 15thDay
12%5%36%5%25%46%7%42%
2016
16th to endDay
12%5%25%4235%5%7%44%
1980
October1st to 15thDay
14%7%26%6%34346%40%
1899
16th to endDay
19%8%26%5%3445%6%33%
1829
November1st to 15thDay
14%7%36%5%34445%39%
1717
16th to endDay
19%11%47%5%24446%28%
1755
December1st to 15thDay
17%14%6%8%7%35%445%21%
1755
16th to endDay
20%15%7%10%7%24445%15%
1607
January1st to 15thNight
22%12%47%5%33345%25%
2506
16th to endNight
16%13%5%8%8%36%5%5%5%21%
2540
February1st to 15thNight
16%14%5%9%6%24445%26%
2239
16th to endNight
17%11%48%5%45%446%27%
1893
March1st to 15thNight
18%9%47%6%34345%32%
2064
16th to endNight
15%8%37%5%34346%36%
2112
April1st to 15thNight
18%7%35%5%3445%6%34%
1827
16th to endNight
15%7%345%35%45%6%39%
1620
May1st to 15thNight
18%6%36%6%36%45%7%31%
1620
16th to endNight
12%5%245%3445%8%42%
1682
June1st to 15thNight
9%4245%35%5%47%45%
1482
16th to endNight
9%415%426%5%6%12%41%
1440
July1st to 15thNight
6%42442446%8%52%
1440
16th to endNight
5%3144245%6%9%52%
1640
August1st to 15thNight
43145%35%5%6%9%49%
1620
16th to endNight
9%325%4235%47%51%
1756
September1st to 15thNight
10%325%424346%51%
1932
16th to endNight
11%425%423347%49%
1980
October1st to 15thNight
13%7%35%423446%44%
2061
16th to endNight
20%7%245%24445%37%
2394
November1st to 15thNight
14%7%36%424447%40%
2471
16th to endNight
20%10%5%6%5%3445%6%27%
2535
December1st to 15thNight
19%13%5%8%6%34445%24%
2535
16th to endNight
23%15%5%8%5%25%445%17%
2713

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
20%15%48%6%45%436%19%
1432
16th to endDay
16%16%9%9%7%45%5%4416%
1682
February1st to 15thDay
16%13%5%9%8%45%45%421%
1618
16th to endDay
16%12%49%7%445%5%6%23%
1580
March1st to 15thDay
20%11%5%8%6%24445%24%
1884
16th to endDay
20%11%47%6%34346%28%
2111
April1st to 15thDay
18%8%46%6%35%5%5%6%29%
2131
16th to endDay
17%6%26%5%23446%39%
2340
May1st to 15thDay
18%8%36%6%445%6%7%29%
2331
16th to endDay
13%425%6%35%5%6%7%39%
2431
June1st to 15thDay
11%6%25%5%35%5%5%7%41%
2475
16th to endDay
11%5%26%6%46%6%6%8%35%
2520
July1st to 15thDay
9%425%445%6%6%9%42%
2520
16th to endDay
9%4245%36%6%7%9%40%
2525
August1st to 15thDay
7%4245%45%6%6%9%41%
2340
16th to endDay
10%425%5%45%6%7%10%38%
2444
September1st to 15thDay
13%5%2443446%7%42%
2016
16th to endDay
13%6%25%41345%7%44%
1980
October1st to 15thDay
14%7%26%6%34445%41%
1899
16th to endDay
19%9%25%5%3445%6%33%
1829
November1st to 15thDay
15%7%36%434446%39%
1717
16th to endDay
19%11%46%5%3445%6%28%
1755
December1st to 15thDay
18%14%5%9%6%3444422%
1755
16th to endDay
20%15%6%10%7%34445%16%
1607
January1st to 15thNight
23%12%47%5%24345%25%
2506
16th to endNight
17%13%6%8%7%45%445%21%
2540
February1st to 15thNight
16%14%5%8%6%24445%27%
2232
16th to endNight
17%11%48%5%35%447%26%
1893
March1st to 15thNight
19%9%47%6%24345%32%
2076
16th to endNight
15%8%36%6%34346%36%
2112
April1st to 15thNight
19%7%346%2445%6%33%
1827
16th to endNight
15%6%35%434447%39%
1620
May1st to 15thNight
19%6%36%5%36%5%5%7%31%
1619
16th to endNight
12%5%25%5%245%48%42%
1682
June1st to 15thNight
10%4245%35%5%5%7%45%
1482
16th to endNight
9%4145%35%5%6%10%42%
1440
July1st to 15thNight
6%42443445%9%51%
1440
16th to endNight
6%21343446%10%51%
1640
August1st to 15thNight
5%314435%5%6%9%49%
1620
16th to endNight
9%3145%145%48%50%
1756
September1st to 15thNight
10%5%24422446%51%
1932
16th to endNight
11%425%5%2335%7%49%
1980
October1st to 15thNight
13%6%35%423446%45%
2061
16th to endNight
20%7%245%24445%37%
2394
November1st to 15thNight
14%7%25%434447%40%
2471
16th to endNight
21%10%46%5%2435%7%27%
2535
December1st to 15thNight
19%12%5%8%5%34446%24%
2535
16th to endNight
23%15%6%8%425%445%17%
2713

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
67%5%12%12%3
1433
16th to endDay
69%7%10%9%3
1682
February1st to 15thDay
65%5%10%13%4
1620
16th to endDay
60%6%13%14%4
1580
March1st to 15thDay
60%7%11%14%5%
1884
16th to endDay
57%410%20%5%
2112
April1st to 15thDay
53%6%11%17%11%
2131
16th to endDay
46%5%11%21%12%3
2340
May1st to 15thDay
51%8%10%17%10%1
2331
16th to endDay
42%7%12%23%12%1
2435
June1st to 15thDay
39%7%13%23%13%2
2475
16th to endDay
43%9%13%17%15%2
2520
July1st to 15thDay
37%7%11%22%18%2
2371
16th to endDay
36%8%16%22%14%1
2369
August1st to 15thDay
35%10%14%22%14%1
2327
16th to endDay
37%9%14%20%14%2
2444
September1st to 15thDay
39%7%12%22%16%1
2016
16th to endDay
37%6%11%27%16%
1980
October1st to 15thDay
44%411%22%14%1
1899
16th to endDay
50%5%14%19%9%
1829
November1st to 15thDay
45%6%10%19%15%1
1717
16th to endDay
56%5%12%17%7%
1755
December1st to 15thDay
64%6%10%13%4
1755
16th to endDay
70%6%11%8%2
1607
January1st to 15thNight
61%411%14%7%
2506
16th to endNight
63%6%13%12%3
2540
February1st to 15thNight
59%6%11%17%41
2241
16th to endNight
56%6%11%18%5%
1893
March1st to 15thNight
54%6%11%17%9%1
2076
16th to endNight
48%5%11%22%9%1
2112
April1st to 15thNight
50%5%11%17%14%
1827
16th to endNight
44%5%11%18%15%4
1620
May1st to 15thNight
51%8%10%17%11%1
1620
16th to endNight
38%7%10%25%14%2
1684
June1st to 15thNight
36%8%11%24%17%1
1482
16th to endNight
33%9%14%23%16%2
1440
July1st to 15thNight
30%7%12%26%20%3
1360
16th to endNight
25%8%17%25%19%3
1534
August1st to 15thNight
29%8%14%28%17%1
1609
16th to endNight
32%6%12%24%20%3
1756
September1st to 15thNight
33%5%12%24%20%3
1932
16th to endNight
34%5%12%25%20%1
1980
October1st to 15thNight
39%6%12%21%18%1
2061
16th to endNight
47%5%12%23%9%1
2394
November1st to 15thNight
42%6%11%22%14%2
2471
16th to endNight
56%5%12%19%7%
2535
December1st to 15thNight
60%5%11%13%7%
2535
16th to endNight
68%6%11%10%3
2713

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
23%20%35%12%6%2
90
16th to endDay
33%17%37%9%2
96
February1st to 15thDay
30%18%41%8%1
90
16th to endDay
19%14%45%18%1
81
March1st to 15thDay
31%14%25%20%6%
174
16th to endDay
25%9%37%18%8%1
288
April1st to 15thDay
21%14%30%23%8%1
270
16th to endDay
20%9%28%20%14%6%
270
May1st to 15thDay
22%7%30%19%14%5%
288
16th to endDay
15%7%28%22%16%9%
331
June1st to 15thDay
11%431%31%16%4
450
16th to endDay
14%5%29%30%14%5%
495
July1st to 15thDay
11%127%30%19%8%
475
16th to endDay
9%318%30%22%15%
385
August1st to 15thDay
11%213%29%25%17%
313
16th to endDay
11%314%25%25%20%
332
September1st to 15thDay
14%315%25%23%16%
315
16th to endDay
14%6%14%19%28%16%
314
October1st to 15thDay
16%7%23%24%20%7%
315
16th to endDay
21%11%32%28%5%1
245
November1st to 15thDay
20%9%25%26%13%5%
135
16th to endDay
23%19%35%17%2
135
December1st to 15thDay
22%27%29%11%8%
135
16th to endDay
27%28%33%9%
108
January1st to 15thNight
28%14%34%17%4
900
16th to endNight
21%14%37%21%4
812
February1st to 15thNight
23%13%34%24%3
704
16th to endNight
23%12%31%29%3
631
March1st to 15thNight
23%10%30%28%6%
720
16th to endNight
17%11%33%26%9%1
768
April1st to 15thNight
21%12%33%25%5%
593
16th to endNight
18%8%32%29%9%1
540
May1st to 15thNight
20%329%32%11%1
540
16th to endNight
13%227%33%20%2
563
June1st to 15thNight
11%225%42%17%
540
16th to endNight
12%123%39%21%1
540
July1st to 15thNight
9%119%42%25%2
510
16th to endNight
6%114%43%29%4
564
August1st to 15thNight
7%114%41%31%4
539
16th to endNight
10%113%33%36%4
573
September1st to 15thNight
12%416%32%28%4
672
16th to endNight
12%316%30%32%4
717
October1st to 15thNight
14%8%22%30%19%4
720
16th to endNight
24%10%31%24%8%
768
November1st to 15thNight
17%11%30%26%11%2
760
16th to endNight
26%12%30%21%8%
780
December1st to 15thNight
24%13%35%21%4
780
16th to endNight
30%10%35%19%3
942
Page generated at 2017-12-21 07:04:48. Version ac04

Copyright 2017 A. Danko


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