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 2017-04-07.

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%
14817
14%
45315
10%
14779
41%
14779
18%
32382

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%
717
9%
2327
4%
716
18%
716
8%
1880
January16th to endNight
16%
768
8%
2496
4%
768
22%
768
9%
1996
February1st to 15thNight
16%
702
7%
2287
3%
701
22%
701
9%
1811
February16th to endNight
21%
631
10%
1893
4%
631
27%
631
11%
1490
March1st to 15thNight
26%
720
13%
2034
8%
720
30%
720
15%
1550
March16th to endNight
33%
768
15%
2112
10%
768
36%
768
19%
1544
April1st to 15thNight
28%
631
12%
1775
6%
631
33%
631
19%
1306
April16th to endNight
38%
495
18%
1485
9%
495
46%
495
23%
1005
May1st to 15thNight
42%
495
13%
1485
9%
495
46%
495
18%
1079
May16th to endNight
55%
513
14%
1540
13%
513
57%
513
28%
969
June1st to 15thNight
53%
380
15%
1370
14%
380
59%
380
24%
851
June16th to endNight
60%
408
16%
1235
16%
408
63%
408
30%
764
July1st to 15thNight
63%
465
16%
1295
15%
465
64%
465
35%
796
July16th to endNight
69%
522
16%
1469
14%
489
70%
489
36%
863
August1st to 15thNight
68%
494
20%
1474
18%
491
68%
491
32%
891
August16th to endNight
63%
525
20%
1575
17%
525
65%
525
32%
951
September1st to 15thNight
63%
654
24%
1784
17%
654
66%
654
35%
1101
September16th to endNight
55%
657
22%
1815
17%
657
58%
657
29%
1180
October1st to 15thNight
46%
660
18%
1925
16%
660
50%
660
25%
1266
October16th to endNight
25%
704
14%
2139
9%
704
32%
704
17%
1548
November1st to 15thNight
32%
700
18%
2276
14%
700
39%
700
20%
1517
November16th to endNight
23%
720
11%
2424
9%
720
27%
720
12%
1829
December1st to 15thNight
16%
720
7%
2520
4%
720
20%
720
8%
2032
December16th to endNight
15%
768
6%
2580
3%
768
19%
768
7%
2163

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%5%3445%7%32%
45892
Night
16%9%46%5%3445%6%32%
45503
Cloud CoverDay
15%9%47%6%35%45%7%31%
45902
Night
15%9%46%5%3445%6%32%
45507
TransparencyDay
51%6%12%18%10%1
45598
Night
51%6%12%17%10%1
45315
SeeingDay
19%8%24%23%16%7%
4916
Night
20%10%26%27%13%1
14824

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%34435%18%
1611
16th to endDay
14%18%8%13%9%44435%12%
1728
February1st to 15thDay
16%16%7%9%8%45%435%19%
1575
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
19%10%46%6%24446%29%
1999
16th to endDay
18%8%35%423336%39%
2145
May1st to 15thDay
16%9%37%6%35%45%6%32%
2136
16th to endDay
10%5%35%5%35%5%6%9%39%
2223
June1st to 15thDay
14%6%244345%5%9%39%
2255
16th to endDay
10%5%25%436%5%7%10%37%
2385
July1st to 15thDay
10%5%245%35%5%6%9%42%
2245
16th to endDay
10%4245%346%7%11%39%
2283
August1st to 15thDay
7%5%26%5%45%6%7%8%41%
2145
16th to endDay
10%6%35%5%35%46%9%40%
2270
September1st to 15thDay
13%5%35%435%45%7%39%
1837
16th to endDay
17%6%345%33446%40%
1815
October1st to 15thDay
15%7%36%5%3445%7%36%
1704
16th to endDay
24%8%35%434446%30%
1733
November1st to 15thDay
14%10%35%435%35%6%36%
1582
16th to endDay
18%16%5%8%7%25%35%5%21%
1533
December1st to 15thDay
20%18%6%9%6%34335%17%
1440
16th to endDay
20%17%7%10%7%33445%14%
1641
January1st to 15thNight
22%14%7%10%6%3334320%
2327
16th to endNight
17%16%6%10%7%34445%20%
2496
February1st to 15thNight
17%12%6%10%7%35%34423%
2285
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%11%46%5%24346%31%
1775
16th to endNight
13%7%36%5%3445%8%36%
1485
May1st to 15thNight
17%6%36%6%35%5%6%9%28%
1485
16th to endNight
11%5%235%35%5%6%8%42%
1538
June1st to 15thNight
10%5%35%5%35%6%5%7%42%
1370
16th to endNight
8%5%25%4345%6%11%42%
1235
July1st to 15thNight
7%4244246%6%10%46%
1380
16th to endNight
7%314425%5%7%10%48%
1577
August1st to 15thNight
7%424425%5%7%9%46%
1485
16th to endNight
9%5%335%2445%6%48%
1575
September1st to 15thNight
10%424334447%49%
1784
16th to endNight
13%6%25%42445%7%43%
1815
October1st to 15thNight
16%6%24434445%42%
1925
16th to endNight
22%8%46%5%3445%5%29%
2139
November1st to 15thNight
15%9%36%5%3345%6%36%
2276
16th to endNight
22%12%47%6%35%246%24%
2424
December1st to 15thNight
22%16%6%8%5%34345%20%
2520
16th to endNight
22%16%6%8%5%44446%14%
2580

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%16%5%9%7%35%435%18%
1611
16th to endDay
15%18%8%13%9%3344412%
1728
February1st to 15thDay
16%16%6%11%7%45%435%19%
1575
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
19%11%45%6%35%446%28%
1999
16th to endDay
18%8%36%424336%39%
2145
May1st to 15thDay
16%8%37%5%45%35%6%31%
2136
16th to endDay
10%5%35%5%35%5%6%8%39%
2223
June1st to 15thDay
13%6%25%4345%5%9%38%
2255
16th to endDay
10%6%245%46%5%7%10%36%
2385
July1st to 15thDay
10%5%25%6%25%5%5%9%41%
2245
16th to endDay
9%4345%36%6%6%10%38%
2283
August1st to 15thDay
7%426%5%45%6%7%9%40%
2145
16th to endDay
10%5%25%5%35%45%9%39%
2270
September1st to 15thDay
13%5%25%5%45%46%7%39%
1837
16th to endDay
17%6%25%5%33446%40%
1815
October1st to 15thDay
14%7%36%5%345%5%6%36%
1704
16th to endDay
23%9%35%43345%6%31%
1733
November1st to 15thDay
14%10%35%5%34447%36%
1582
16th to endDay
17%16%5%7%7%25%5%45%21%
1533
December1st to 15thDay
20%18%6%9%6%25%44417%
1440
16th to endDay
19%18%7%10%7%34345%14%
1641
January1st to 15thNight
21%15%7%10%6%4334320%
2327
16th to endNight
16%16%6%9%7%34435%20%
2496
February1st to 15thNight
17%13%6%10%6%35%34423%
2278
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%35%5%31%
1775
16th to endNight
13%7%36%5%245%5%8%36%
1485
May1st to 15thNight
16%7%46%5%35%5%7%8%29%
1484
16th to endNight
10%5%236%25%5%6%8%42%
1538
June1st to 15thNight
9%5%35%5%35%5%5%7%42%
1370
16th to endNight
8%5%25%445%5%6%11%41%
1235
July1st to 15thNight
7%4245%25%6%6%10%46%
1380
16th to endNight
7%2244245%7%10%48%
1577
August1st to 15thNight
7%424435%5%7%8%47%
1485
16th to endNight
9%5%245%2445%7%48%
1575
September1st to 15thNight
10%423425%447%50%
1784
16th to endNight
13%5%25%42445%7%44%
1815
October1st to 15thNight
16%6%25%435%445%42%
1925
16th to endNight
21%8%36%6%3445%6%29%
2139
November1st to 15thNight
15%8%36%5%3445%6%36%
2276
16th to endNight
21%12%48%6%36%246%24%
2424
December1st to 15thNight
21%15%7%8%435%445%20%
2520
16th to endNight
22%16%6%8%6%34445%15%
2580

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
68%5%11%10%4
1612
16th to endDay
74%5%10%7%1
1728
February1st to 15thDay
68%410%11%4
1577
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
55%5%11%14%11%
1999
16th to endDay
47%5%10%19%13%2
2145
May1st to 15thDay
52%6%12%19%8%1
2136
16th to endDay
40%7%12%24%12%2
2227
June1st to 15thDay
41%7%12%23%13%
2255
16th to endDay
41%8%14%18%14%2
2385
July1st to 15thDay
40%6%11%20%18%1
2101
16th to endDay
37%8%15%24%12%1
2128
August1st to 15thDay
38%7%14%25%12%
2132
16th to endDay
40%6%13%22%13%3
2270
September1st to 15thDay
41%7%13%20%13%2
1837
16th to endDay
45%5%9%20%18%
1815
October1st to 15thDay
45%7%11%19%14%1
1704
16th to endDay
53%5%15%17%7%
1733
November1st to 15thDay
47%5%11%20%12%2
1582
16th to endDay
63%6%9%14%6%
1533
December1st to 15thDay
70%5%9%9%3
1440
16th to endDay
73%5%9%9%2
1641
January1st to 15thNight
67%410%11%5%
2327
16th to endNight
65%5%13%11%3
2496
February1st to 15thNight
64%5%10%13%4
2287
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%411%15%13%1
1775
16th to endNight
44%6%10%17%16%4
1485
May1st to 15thNight
49%9%12%17%10%1
1485
16th to endNight
37%7%14%22%15%2
1540
June1st to 15thNight
38%8%12%22%17%
1370
16th to endNight
35%7%16%22%15%3
1235
July1st to 15thNight
32%7%12%22%21%3
1295
16th to endNight
28%8%18%23%16%4
1469
August1st to 15thNight
31%8%14%24%18%1
1474
16th to endNight
34%5%13%24%17%3
1575
September1st to 15thNight
33%5%13%24%18%4
1784
16th to endNight
38%6%10%23%19%1
1815
October1st to 15thNight
42%5%12%19%17%1
1925
16th to endNight
52%5%12%20%6%1
2139
November1st to 15thNight
46%5%13%17%13%3
2276
16th to endNight
61%412%15%6%
2424
December1st to 15thNight
66%6%12%11%3
2520
16th to endNight
69%6%11%10%1
2580

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%25%28%7%8%3
90
16th to endDay
31%18%36%12%1
96
February1st to 15thDay
32%23%35%8%
90
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
25%14%25%21%8%3
235
16th to endDay
24%6%28%17%14%9%
210
May1st to 15thDay
23%5%31%23%12%4
228
16th to endDay
17%423%27%17%9%
267
June1st to 15thDay
16%5%22%30%20%4
255
16th to endDay
14%5%25%32%18%4
414
July1st to 15thDay
14%420%29%19%11%
340
16th to endDay
10%119%26%27%14%
270
August1st to 15thDay
12%116%28%27%14%
253
16th to endDay
14%211%23%27%20%
268
September1st to 15thDay
10%5%14%19%28%21%
255
16th to endDay
22%5%14%20%22%14%
254
October1st to 15thDay
14%6%24%27%20%6%
255
16th to endDay
25%15%32%19%6%
245
November1st to 15thDay
17%12%17%33%16%2
90
16th to endDay
26%26%32%10%4
75
December1st to 15thDay
23%23%31%13%35%
60
16th to endDay
25%28%35%9%
81
January1st to 15thNight
30%18%32%14%4
720
16th to endNight
24%16%35%19%4
768
February1st to 15thNight
23%18%31%22%3
704
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
23%13%29%27%5%
631
16th to endNight
17%8%31%29%11%2
495
May1st to 15thNight
18%6%24%36%12%1
495
16th to endNight
13%419%34%24%4
515
June1st to 15thNight
10%223%46%17%
380
16th to endNight
11%319%42%22%
408
July1st to 15thNight
10%115%41%29%2
465
16th to endNight
8%113%44%28%3
522
August1st to 15thNight
10%112%42%27%5%
494
16th to endNight
11%214%30%36%4
525
September1st to 15thNight
13%314%32%30%5%
654
16th to endNight
16%5%14%30%27%5%
657
October1st to 15thNight
19%5%23%29%19%2
660
16th to endNight
25%13%32%22%6%
704
November1st to 15thNight
20%10%31%24%10%2
700
16th to endNight
29%14%28%18%8%
720
December1st to 15thNight
29%16%31%17%4
720
16th to endNight
28%16%33%19%2
768
Page generated at 2017-04-08 05:35:18. Version ac04

Copyright 2017 A. Danko


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