Oberlin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oberlin clear sky chart from 2005-11-05 to 2018-02-14.

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
36%
15901
14%
48677
10%
15863
41%
15863
18%
34638

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
12%
777
9%
2522
4%
776
18%
776
9%
2024
January16th to endNight
15%
832
8%
2704
4%
832
21%
832
9%
2153
February1st to 15thNight
15%
758
7%
2468
3%
757
21%
757
9%
1964
February16th to endNight
21%
631
10%
1893
4%
631
27%
631
11%
1490
March1st to 15thNight
26%
720
13%
2034
8%
720
31%
720
15%
1550
March16th to endNight
34%
768
15%
2112
10%
768
37%
768
19%
1544
April1st to 15thNight
29%
658
12%
1852
6%
658
34%
658
19%
1359
April16th to endNight
37%
540
19%
1620
9%
540
45%
540
24%
1091
May1st to 15thNight
41%
540
12%
1620
8%
540
44%
540
18%
1176
May16th to endNight
52%
561
15%
1684
12%
561
55%
561
27%
1068
June1st to 15thNight
54%
414
14%
1494
14%
414
59%
414
25%
909
June16th to endNight
57%
445
17%
1347
15%
445
61%
445
30%
830
July1st to 15thNight
63%
510
15%
1421
14%
510
64%
510
35%
877
July16th to endNight
70%
564
17%
1595
15%
531
72%
531
37%
931
August1st to 15thNight
68%
539
19%
1609
17%
536
69%
536
33%
967
August16th to endNight
63%
573
21%
1719
18%
573
65%
573
33%
1034
September1st to 15thNight
61%
714
23%
1947
16%
714
65%
714
34%
1210
September16th to endNight
56%
717
24%
1980
19%
717
60%
717
31%
1267
October1st to 15thNight
46%
720
18%
2100
16%
720
49%
720
25%
1385
October16th to endNight
26%
768
16%
2334
11%
768
33%
768
17%
1675
November1st to 15thNight
32%
760
16%
2471
13%
760
38%
760
19%
1668
November16th to endNight
22%
780
12%
2626
8%
780
27%
780
12%
1964
December1st to 15thNight
17%
780
7%
2730
4%
780
21%
780
9%
2172
December16th to endNight
14%
832
6%
2795
2%
832
19%
832
7%
2330

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%9%46%6%3445%7%32%
49370
Night
15%9%46%5%3445%6%32%
48865
Cloud CoverDay
15%9%47%6%35%45%7%32%
49380
Night
15%9%46%5%3445%6%33%
48869
TransparencyDay
51%6%12%18%10%1
49076
Night
50%6%12%18%11%1
48677
SeeingDay
18%9%25%22%15%7%
6047
Night
20%10%26%27%13%1
15908

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%15%6%9%7%44435%17%
1746
16th to endDay
15%18%8%12%9%44435%13%
1872
February1st to 15thDay
17%15%7%10%8%4443419%
1695
16th to endDay
15%13%6%11%8%34445%22%
1580
March1st to 15thDay
21%12%5%7%6%33445%24%
1915
16th to endDay
19%9%5%7%5%25%445%29%
2112
April1st to 15thDay
18%10%46%6%245%5%6%29%
2106
16th to endDay
17%8%25%5%24336%39%
2340
May1st to 15thDay
16%9%36%6%34446%32%
2331
16th to endDay
11%5%35%5%35%5%6%8%39%
2431
June1st to 15thDay
13%5%244345%5%8%40%
2460
16th to endDay
10%5%24436%5%6%10%38%
2602
July1st to 15thDay
9%5%25%5%35%5%5%9%41%
2449
16th to endDay
9%424435%6%7%11%40%
2465
August1st to 15thDay
7%425%5%46%6%7%8%41%
2340
16th to endDay
10%6%35%5%35%46%9%39%
2477
September1st to 15thDay
13%5%35%5%35%45%7%39%
2004
16th to endDay
16%6%245%335%47%41%
1980
October1st to 15thDay
15%7%36%5%3445%7%35%
1859
16th to endDay
23%8%35%434346%31%
1890
November1st to 15thDay
15%11%36%435%35%6%34%
1717
16th to endDay
17%16%5%7%7%25%35%5%22%
1661
December1st to 15thDay
19%17%7%10%7%34335%17%
1560
16th to endDay
20%17%7%10%8%33345%14%
1778
January1st to 15thNight
21%14%6%9%7%3344321%
2522
16th to endNight
17%15%6%10%7%34445%20%
2704
February1st to 15thNight
18%13%6%10%7%3434423%
2466
16th to endNight
17%13%5%10%6%35%445%22%
1893
March1st to 15thNight
18%11%5%7%5%34445%28%
2022
16th to endNight
15%9%46%6%345%46%33%
2112
April1st to 15thNight
17%10%36%5%2445%7%31%
1852
16th to endNight
13%6%36%5%3445%8%37%
1620
May1st to 15thNight
17%6%36%5%35%5%6%8%29%
1620
16th to endNight
10%5%245%35%5%6%8%41%
1682
June1st to 15thNight
9%4345%35%6%5%7%44%
1494
16th to endNight
8%5%25%4345%6%11%42%
1347
July1st to 15thNight
7%4244246%6%9%46%
1506
16th to endNight
6%314425%47%10%48%
1703
August1st to 15thNight
6%424425%5%7%9%46%
1620
16th to endNight
9%5%245%245%6%6%47%
1719
September1st to 15thNight
11%423434446%49%
1947
16th to endNight
12%5%25%42445%7%45%
1980
October1st to 15thNight
16%6%24434445%42%
2100
16th to endNight
21%7%46%5%3445%5%31%
2334
November1st to 15thNight
16%9%36%5%3445%6%34%
2471
16th to endNight
22%12%47%6%35%346%24%
2626
December1st to 15thNight
21%15%6%8%5%34345%21%
2730
16th to endNight
22%16%6%8%5%44446%15%
2795

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%16%5%9%7%45%43417%
1746
16th to endDay
15%18%8%13%9%3344414%
1872
February1st to 15thDay
17%15%6%11%8%35%435%18%
1695
16th to endDay
15%13%5%12%7%43445%22%
1580
March1st to 15thDay
21%13%5%7%6%34345%23%
1926
16th to endDay
19%9%5%7%6%35%436%28%
2111
April1st to 15thDay
18%11%45%6%35%446%29%
2106
16th to endDay
17%7%36%424336%39%
2340
May1st to 15thDay
17%8%37%5%35%35%6%32%
2331
16th to endDay
11%5%35%5%35%5%6%8%39%
2431
June1st to 15thDay
13%6%25%4345%5%8%39%
2460
16th to endDay
10%5%245%46%5%6%10%37%
2602
July1st to 15thDay
10%5%25%6%35%5%5%9%40%
2449
16th to endDay
9%4345%36%6%6%11%39%
2465
August1st to 15thDay
7%426%5%46%6%7%8%40%
2340
16th to endDay
10%6%26%5%35%5%5%9%39%
2477
September1st to 15thDay
13%6%25%5%4446%7%38%
2004
16th to endDay
16%6%25%5%33447%41%
1980
October1st to 15thDay
15%7%36%5%345%5%6%36%
1859
16th to endDay
22%9%35%42345%6%32%
1890
November1st to 15thDay
14%11%35%5%34447%34%
1717
16th to endDay
17%16%5%7%6%35%5%5%5%22%
1661
December1st to 15thDay
19%17%6%10%6%35%34418%
1560
16th to endDay
19%18%7%10%7%44345%14%
1778
January1st to 15thNight
20%14%6%10%6%4334321%
2522
16th to endNight
16%16%6%9%7%34436%20%
2704
February1st to 15thNight
18%13%6%10%6%35%34422%
2459
16th to endNight
17%13%6%10%6%45%445%22%
1893
March1st to 15thNight
18%11%5%7%5%34445%28%
2034
16th to endNight
15%8%5%6%6%245%46%33%
2112
April1st to 15thNight
17%10%46%6%25%36%5%31%
1852
16th to endNight
13%7%36%5%345%5%7%37%
1620
May1st to 15thNight
16%7%46%5%35%5%7%8%29%
1619
16th to endNight
10%6%236%245%6%8%42%
1682
June1st to 15thNight
9%435%5%35%5%5%7%44%
1494
16th to endNight
8%5%244346%6%11%41%
1347
July1st to 15thNight
7%4245%245%6%10%45%
1506
16th to endNight
6%2244245%7%10%49%
1703
August1st to 15thNight
6%414435%5%7%8%47%
1620
16th to endNight
9%5%2442445%7%48%
1719
September1st to 15thNight
11%423425%446%49%
1947
16th to endNight
12%5%25%424446%46%
1980
October1st to 15thNight
16%6%25%435%345%42%
2100
16th to endNight
20%7%35%6%3445%6%30%
2334
November1st to 15thNight
16%9%36%43445%6%35%
2471
16th to endNight
21%12%47%6%36%346%25%
2626
December1st to 15thNight
20%15%6%8%435%445%21%
2730
16th to endNight
21%16%6%8%6%34445%16%
2795

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%5%10%9%4
1747
16th to endDay
72%5%11%8%1
1872
February1st to 15thDay
69%49%11%4
1697
16th to endDay
63%413%12%4
1580
March1st to 15thDay
63%5%11%14%5%
1926
16th to endDay
57%5%9%19%7%
2112
April1st to 15thDay
54%5%12%15%10%
2106
16th to endDay
47%5%11%19%13%3
2340
May1st to 15thDay
52%6%11%18%8%2
2331
16th to endDay
40%7%13%24%12%1
2435
June1st to 15thDay
41%7%12%24%13%
2460
16th to endDay
40%8%14%19%14%1
2602
July1st to 15thDay
40%6%11%21%17%1
2305
16th to endDay
36%8%15%24%13%2
2310
August1st to 15thDay
38%8%15%24%12%1
2327
16th to endDay
40%6%13%22%13%3
2477
September1st to 15thDay
42%7%13%20%13%2
2004
16th to endDay
43%5%10%20%19%
1980
October1st to 15thDay
45%7%11%18%14%1
1859
16th to endDay
52%415%17%8%
1890
November1st to 15thDay
50%5%11%19%11%2
1717
16th to endDay
61%6%11%14%6%
1661
December1st to 15thDay
70%5%9%10%3
1560
16th to endDay
73%5%9%9%2
1778
January1st to 15thNight
66%410%12%6%
2522
16th to endNight
65%5%14%11%3
2704
February1st to 15thNight
65%5%10%13%4
2468
16th to endNight
62%6%10%15%5%
1893
March1st to 15thNight
57%5%10%17%8%1
2034
16th to endNight
50%7%10%20%8%1
2112
April1st to 15thNight
53%5%11%16%13%1
1852
16th to endNight
44%6%11%17%16%4
1620
May1st to 15thNight
49%8%11%16%10%1
1620
16th to endNight
37%7%14%22%15%2
1684
June1st to 15thNight
37%7%12%23%17%
1494
16th to endNight
35%7%16%22%15%2
1347
July1st to 15thNight
32%7%12%23%20%2
1421
16th to endNight
27%8%17%24%17%4
1595
August1st to 15thNight
30%8%14%25%18%1
1609
16th to endNight
33%6%13%24%18%3
1719
September1st to 15thNight
34%5%13%24%17%3
1947
16th to endNight
37%6%10%23%20%1
1980
October1st to 15thNight
43%5%12%19%18%1
2100
16th to endNight
51%5%11%21%7%1
2334
November1st to 15thNight
47%6%13%17%12%3
2471
16th to endNight
59%412%15%6%
2626
December1st to 15thNight
64%6%12%11%5%
2730
16th to endNight
69%6%11%10%1
2795

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
25%22%34%7%8%2
135
16th to endDay
30%19%36%12%
144
February1st to 15thDay
34%20%34%10%
130
16th to endDay
18%20%43%17%
81
March1st to 15thDay
26%17%31%16%7%
216
16th to endDay
26%9%33%20%8%1
288
April1st to 15thDay
24%14%27%21%8%2
270
16th to endDay
22%9%30%17%13%7%
270
May1st to 15thDay
24%7%30%21%12%3
288
16th to endDay
17%6%27%25%15%7%
331
June1st to 15thDay
14%5%23%33%20%4
315
16th to endDay
14%6%28%30%16%3
489
July1st to 15thDay
13%422%30%18%10%
409
16th to endDay
9%220%26%27%14%
326
August1st to 15thDay
11%118%26%27%13%
313
16th to endDay
12%413%26%25%17%
332
September1st to 15thDay
14%5%17%19%25%18%
315
16th to endDay
19%6%14%18%24%16%
314
October1st to 15thDay
16%6%24%25%20%6%
315
16th to endDay
23%17%31%20%6%
306
November1st to 15thDay
22%15%20%24%14%2
135
16th to endDay
25%24%35%11%2
113
December1st to 15thDay
21%23%36%11%43
90
16th to endDay
23%31%36%8%
122
January1st to 15thNight
29%17%32%15%4
780
16th to endNight
24%16%36%19%3
832
February1st to 15thNight
25%18%31%21%3
760
16th to endNight
23%13%34%24%3
631
March1st to 15thNight
24%13%30%24%6%
720
16th to endNight
18%10%31%26%11%1
768
April1st to 15thNight
22%13%29%27%5%
658
16th to endNight
17%7%33%28%10%1
540
May1st to 15thNight
19%6%24%35%12%1
540
16th to endNight
13%421%33%23%3
563
June1st to 15thNight
10%223%44%17%
414
16th to endNight
11%222%41%20%
445
July1st to 15thNight
10%116%41%28%1
510
16th to endNight
8%113%43%29%3
564
August1st to 15thNight
9%112%42%27%5%
539
16th to endNight
10%115%31%36%4
573
September1st to 15thNight
14%315%32%29%5%
714
16th to endNight
15%5%14%29%28%6%
717
October1st to 15thNight
20%5%21%29%19%2
720
16th to endNight
24%13%32%22%7%
768
November1st to 15thNight
21%10%30%25%10%1
760
16th to endNight
29%15%28%18%8%
780
December1st to 15thNight
28%17%31%17%5%
780
16th to endNight
28%16%33%19%2
832
Page generated at 2018-02-15 10:58:51. Version ac04

Copyright 2018 A. Danko


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