Buckeyestargazer Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Buckeyestargazer Observatory clear sky chart from 2005-11-06 to 2024-03-23.

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%
24823
16%
80952
10%
24719
42%
24719
19%
56451

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 10thNight
18%
940
8%
4414
4%
926
26%
926
8%
3445
January11th to 20thNight
16%
950
7%
4407
3%
930
22%
930
7%
3627
January21st to endNight
19%
1041
7%
4845
3%
1023
25%
1023
7%
3919
February1st to 10thNight
19%
823
12%
2343
4%
823
25%
823
15%
1762
February11th to 20thNight
24%
740
17%
2219
7%
740
34%
740
18%
1556
February21st to endNight
18%
628
15%
1884
4%
628
28%
628
14%
1403
March1st to 10thNight
24%
760
13%
2280
7%
760
29%
760
17%
1637
March11th to 20thNight
28%
760
21%
2207
9%
760
38%
760
25%
1438
March21st to endNight
28%
657
15%
2057
9%
657
36%
657
18%
1470
April1st to 10thNight
28%
540
15%
1800
10%
540
37%
540
21%
1191
April11th to 20thNight
31%
533
20%
1775
13%
533
42%
533
20%
1190
April21st to endNight
30%
540
17%
1658
8%
540
39%
540
21%
1145
May1st to 10thNight
36%
540
14%
1620
8%
540
41%
540
21%
1138
May11th to 20thNight
41%
531
16%
1570
9%
531
47%
531
24%
1075
May21st to endNight
52%
583
16%
1552
10%
582
56%
582
28%
1040
June1st to 10thNight
58%
540
17%
1440
12%
540
63%
540
37%
878
June11th to 20thNight
51%
540
19%
1440
13%
540
56%
540
34%
904
June21st to endNight
53%
540
17%
1440
11%
540
58%
540
30%
954
July1st to 10thNight
68%
525
17%
1400
14%
525
70%
525
39%
848
July11th to 20thNight
63%
522
22%
1392
18%
522
66%
522
40%
831
July21st to endNight
70%
591
24%
1487
18%
558
72%
558
42%
872
August1st to 10thNight
74%
537
23%
1548
22%
534
75%
534
39%
892
August11th to 20thNight
66%
534
21%
1703
21%
534
69%
534
35%
958
August21st to endNight
66%
594
23%
1980
23%
594
71%
594
34%
1105
September1st to 10thNight
60%
540
24%
1800
22%
540
64%
540
30%
1041
September11th to 20thNight
63%
684
32%
1944
27%
684
67%
684
39%
1123
September21st to endNight
53%
720
26%
1980
18%
720
58%
720
32%
1234
October1st to 10thNight
50%
720
24%
1980
18%
720
54%
720
33%
1240
October11th to 20thNight
32%
720
20%
2182
11%
720
43%
720
23%
1402
October21st to endNight
27%
792
17%
2574
11%
792
36%
792
18%
1763
November1st to 10thNight
30%
740
22%
2406
14%
740
41%
740
23%
1512
November11th to 20thNight
24%
760
18%
2470
8%
760
37%
760
17%
1683
November21st to endNight
25%
760
17%
2470
10%
760
34%
760
17%
1721
December1st to 10thNight
18%
909
11%
2619
4%
909
25%
909
16%
1947
December11th to 20thNight
22%
950
12%
3220
5%
948
29%
948
12%
2469
December21st to endNight
13%
1039
5%
4846
3%
1026
18%
1026
5%
4038

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%9%47%6%35%5%6%8%34%
78623
Night
15%10%47%6%345%5%6%35%
81314
TransparencyDay
48%6%12%21%12%2
78324
Night
49%6%11%20%12%2
81134
SeeingDay
17%11%29%25%14%5%
14793
Night
18%10%30%29%12%1
24847

By Month

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 10thDay
15%14%11%11%8%35%5%5%5%18%
2527
11th to 20thDay
14%13%8%13%9%5%5%7%7%414%
2530
21st to endDay
23%23%6%9%5%24345%15%
2783
February1st to 10thDay
16%13%5%9%7%5%5%446%25%
1835
11th to 20thDay
14%10%5%7%7%345%5%7%31%
1848
21st to endDay
16%13%6%10%435%45%6%27%
1570
March1st to 10thDay
18%12%5%7%6%4445%6%29%
1900
11th to 20thDay
14%10%47%7%35%5%6%8%33%
1972
21st to endDay
21%10%5%8%7%345%47%26%
2359
April1st to 10thDay
16%9%47%7%345%6%8%31%
2160
11th to 20thDay
18%10%46%5%34448%36%
2134
21st to endDay
20%8%36%5%35%5%5%7%33%
2300
May1st to 10thDay
18%8%36%5%35%5%6%8%32%
2340
11th to 20thDay
18%9%45%6%3445%8%36%
2321
21st to endDay
11%6%36%6%35%5%6%9%40%
2725
June1st to 10thDay
10%5%25%6%36%5%5%9%44%
2520
11th to 20thDay
9%5%25%6%35%5%6%9%45%
2520
21st to endDay
10%5%26%6%46%6%7%9%39%
2520
July1st to 10thDay
8%5%25%6%35%5%6%10%45%
2520
11th to 20thDay
9%4245%445%7%10%45%
2520
21st to endDay
6%5%25%6%46%6%7%10%44%
2743
August1st to 10thDay
7%5%25%6%35%6%7%10%45%
2380
11th to 20thDay
8%5%26%5%35%6%6%9%44%
2195
21st to endDay
8%425%435%46%9%49%
2376
September1st to 10thDay
10%5%25%445%6%6%8%44%
2160
11th to 20thDay
11%5%245%25%46%8%46%
1998
21st to endDay
10%5%26%6%345%6%10%43%
1980
October1st to 10thDay
11%7%46%425%5%5%7%44%
1980
11th to 20thDay
19%7%37%5%35%5%6%7%34%
1774
21st to endDay
20%9%37%6%35%5%5%6%29%
1782
November1st to 10thDay
12%7%35%5%3446%7%43%
1672
11th to 20thDay
18%9%47%5%345%5%7%32%
1710
21st to endDay
18%11%48%6%3435%5%33%
1710
December1st to 10thDay
16%14%5%8%7%445%5%6%26%
1558
11th to 20thDay
14%14%6%12%7%445%47%24%
1918
21st to endDay
23%22%7%12%7%3334413%
2783
January1st to 10thNight
17%16%9%10%7%3444423%
4428
11th to 20thNight
15%19%8%12%7%346%6%415%
4440
21st to endNight
23%16%7%10%6%3444419%
4880
February1st to 10thNight
16%13%5%8%7%4435%6%29%
2343
11th to 20thNight
15%10%47%6%44448%35%
2218
21st to endNight
20%12%47%5%34445%31%
1884
March1st to 10thNight
16%10%5%8%6%35%5%45%33%
2280
11th to 20thNight
13%7%36%6%3445%8%41%
2207
21st to endNight
20%8%47%5%35%46%7%30%
2057
April1st to 10thNight
14%7%36%6%46%5%6%8%37%
1800
11th to 20thNight
18%8%36%5%34446%38%
1775
21st to endNight
18%8%37%7%35%5%5%6%36%
1658
May1st to 10thNight
17%7%46%6%45%5%5%7%35%
1620
11th to 20thNight
17%7%37%5%2446%6%39%
1570
21st to endNight
10%5%27%6%46%5%6%8%42%
1551
June1st to 10thNight
9%5%35%4245%6%9%49%
1440
11th to 20thNight
8%6%15%6%345%6%9%47%
1440
21st to endNight
10%5%25%6%45%6%6%9%42%
1440
July1st to 10thNight
6%5%245%345%5%10%51%
1440
11th to 20thNight
8%4244345%5%8%54%
1440
21st to endNight
5%3235%36%5%7%10%51%
1575
August1st to 10thNight
7%423435%6%7%11%50%
1557
11th to 20thNight
7%4345%345%6%8%52%
1703
21st to endNight
8%324425%5%6%8%52%
1980
September1st to 10thNight
11%5%25%433446%51%
1800
11th to 20thNight
9%425%42346%7%54%
1944
21st to endNight
10%6%25%5%35%46%8%47%
1980
October1st to 10thNight
12%5%35%43445%6%49%
1980
11th to 20thNight
18%8%35%423446%42%
2182
21st to endNight
21%9%36%42345%6%36%
2574
November1st to 10thNight
13%8%46%43446%6%42%
2406
11th to 20thNight
15%9%37%5%35%5%5%7%34%
2470
21st to endNight
19%9%46%5%345%5%6%33%
2470
December1st to 10thNight
16%13%5%8%6%35%5%5%6%29%
2619
11th to 20thNight
16%13%5%9%7%45%5%46%27%
3279
21st to endNight
24%18%6%9%7%35%445%15%
4884

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 10thDay
66%5%12%12%5%
2528
11th to 20thDay
70%5%8%11%6%
2530
21st to endDay
72%48%13%3
2783
February1st to 10thDay
61%412%15%7%1
1835
11th to 20thDay
52%5%10%23%9%1
1858
21st to endDay
56%6%12%18%6%2
1570
March1st to 10thDay
56%5%10%20%7%1
1900
11th to 20thDay
49%6%11%22%9%1
1972
21st to endDay
59%6%11%19%5%1
2359
April1st to 10thDay
50%6%11%21%12%
2160
11th to 20thDay
48%5%10%22%12%3
2134
21st to endDay
49%6%13%17%12%2
2300
May1st to 10thDay
50%6%12%23%8%1
2340
11th to 20thDay
49%6%11%20%13%2
2325
21st to endDay
41%8%11%23%16%2
2725
June1st to 10thDay
36%7%11%25%17%3
2520
11th to 20thDay
35%8%10%23%20%3
2520
21st to endDay
39%10%15%19%16%2
2520
July1st to 10thDay
34%8%14%24%17%4
2451
11th to 20thDay
33%8%15%26%15%3
2445
21st to endDay
34%8%15%25%15%4
2591
August1st to 10thDay
32%8%16%28%14%2
2365
11th to 20thDay
34%9%15%24%16%2
2195
21st to endDay
31%7%12%26%19%5%
2376
September1st to 10thDay
36%7%13%23%16%4
2160
11th to 20thDay
33%8%12%26%18%3
1998
21st to endDay
37%6%11%24%19%2
1980
October1st to 10thDay
39%7%11%23%18%2
1980
11th to 20thDay
48%5%11%23%13%1
1774
21st to endDay
55%5%11%19%8%1
1782
November1st to 10thDay
40%6%15%22%15%2
1672
11th to 20thDay
52%5%11%22%9%1
1710
21st to endDay
56%311%21%8%1
1710
December1st to 10thDay
60%5%13%16%6%
1558
11th to 20thDay
61%5%11%19%4
1915
21st to endDay
77%5%8%7%3
2783
January1st to 10thNight
64%6%11%14%5%
4428
11th to 20thNight
71%410%11%4
4440
21st to endNight
69%49%13%5%
4880
February1st to 10thNight
58%410%17%9%1
2343
11th to 20thNight
50%5%11%21%11%1
2219
21st to endNight
55%6%9%18%10%2
1884
March1st to 10thNight
52%6%11%20%10%1
2280
11th to 20thNight
42%6%13%23%14%3
2207
21st to endNight
52%6%12%21%9%1
2057
April1st to 10thNight
45%6%13%22%13%1
1800
11th to 20thNight
48%5%7%21%16%3
1775
21st to endNight
48%6%10%19%14%3
1658
May1st to 10thNight
48%7%11%22%11%1
1620
11th to 20thNight
45%7%11%21%16%1
1571
21st to endNight
39%8%13%21%16%3
1552
June1st to 10thNight
31%7%14%26%20%2
1440
11th to 20thNight
34%7%11%24%22%3
1440
21st to endNight
38%8%15%22%14%3
1440
July1st to 10thNight
29%8%15%25%19%4
1400
11th to 20thNight
28%7%12%26%23%3
1392
21st to endNight
26%8%16%27%17%5%
1487
August1st to 10thNight
27%8%16%31%18%1
1548
11th to 20thNight
29%7%16%25%20%2
1703
21st to endNight
29%7%12%26%21%6%
1980
September1st to 10thNight
33%6%12%24%18%6%
1800
11th to 20thNight
29%6%8%29%24%4
1944
21st to endNight
35%7%9%27%20%3
1980
October1st to 10thNight
35%5%10%26%21%1
1980
11th to 20thNight
43%410%24%17%2
2182
21st to endNight
49%5%10%23%11%1
2574
November1st to 10thNight
42%5%10%24%17%2
2406
11th to 20thNight
49%5%12%22%10%1
2470
21st to endNight
52%412%23%8%
2470
December1st to 10thNight
56%5%13%18%8%
2619
11th to 20thNight
58%7%11%18%6%1
3281
21st to endNight
72%5%10%9%4
4884

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 10thDay
23%14%33%24%6%1
270
11th to 20thDay
23%19%36%15%5%1
270
21st to endDay
24%18%33%20%5%
297
February1st to 10thDay
20%20%37%18%5%
270
11th to 20thDay
23%18%35%20%4
270
21st to endDay
24%19%40%14%4
225
March1st to 10thDay
23%21%36%17%3
270
11th to 20thDay
21%18%35%19%7%
342
21st to endDay
28%16%29%19%7%1
470
April1st to 10thDay
24%12%33%23%7%1
420
11th to 20thDay
22%16%32%16%12%3
412
21st to endDay
24%15%31%20%8%2
420
May1st to 10thDay
23%13%30%22%10%3
423
11th to 20thDay
23%8%31%21%14%3
467
21st to endDay
14%8%29%25%17%8%
679
June1st to 10thDay
12%6%28%29%20%5%
630
11th to 20thDay
12%5%31%28%20%4
630
21st to endDay
12%8%30%32%13%5%
630
July1st to 10thDay
8%5%20%31%22%14%
621
11th to 20thDay
10%5%24%31%21%10%
618
21st to endDay
9%425%34%21%8%
684
August1st to 10thDay
9%316%30%27%14%
499
11th to 20thDay
10%420%28%26%12%
439
21st to endDay
11%416%34%26%9%
495
September1st to 10thDay
12%5%20%33%23%7%
450
11th to 20thDay
10%417%28%26%14%
450
21st to endDay
12%11%25%24%20%9%
450
October1st to 10thDay
14%8%28%31%15%5%
450
11th to 20thDay
18%22%26%25%8%
298
21st to endDay
31%13%37%15%21
297
November1st to 10thDay
15%12%38%23%9%3
270
11th to 20thDay
21%19%34%17%7%1
270
21st to endDay
27%11%39%20%3
270
December1st to 10thDay
18%20%37%18%6%
270
11th to 20thDay
19%19%40%19%41
270
21st to endDay
26%22%36%14%2
297
January1st to 10thNight
22%15%36%22%5%
950
11th to 20thNight
23%15%37%21%41
950
21st to endNight
22%14%34%25%4
1045
February1st to 10thNight
23%13%38%23%3
823
11th to 20thNight
21%14%35%25%4
743
21st to endNight
26%15%36%19%2
628
March1st to 10thNight
21%13%37%23%6%
760
11th to 20thNight
17%11%40%25%6%
760
21st to endNight
23%11%33%26%6%
657
April1st to 10thNight
17%12%39%25%6%1
540
11th to 20thNight
23%8%35%26%7%1
533
21st to endNight
21%9%32%29%8%1
540
May1st to 10thNight
20%7%34%29%9%1
540
11th to 20thNight
19%5%27%34%13%1
531
21st to endNight
12%423%39%21%2
584
June1st to 10thNight
11%321%46%19%
540
11th to 20thNight
11%327%40%18%1
540
21st to endNight
11%325%41%19%1
540
July1st to 10thNight
8%214%45%26%6%
525
11th to 20thNight
8%319%38%28%4
522
21st to endNight
6%216%45%30%1
591
August1st to 10thNight
7%19%48%31%4
537
11th to 20thNight
8%113%41%32%5%
534
21st to endNight
9%217%37%32%3
594
September1st to 10thNight
13%317%36%27%4
540
11th to 20thNight
9%419%37%28%4
684
21st to endNight
12%6%24%32%23%3
720
October1st to 10thNight
14%5%26%35%19%1
720
11th to 20thNight
23%13%29%26%8%
720
21st to endNight
26%11%31%25%6%
792
November1st to 10thNight
18%11%37%22%10%1
740
11th to 20thNight
20%18%33%24%6%
760
21st to endNight
23%14%34%23%6%
760
December1st to 10thNight
24%15%35%22%3
909
11th to 20thNight
23%12%35%25%4
950
21st to endNight
30%14%33%20%3
1045
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