Beaver Island
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beaver Island clear sky chart from 2005-11-06 to 2024-01-16.

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
26%
24047
12%
74802
6%
23987
32%
23987
14%
55857

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
15%
850
10%
2649
2%
847
23%
847
10%
2054
January11th to 20thNight
14%
829
8%
2601
2%
829
22%
829
9%
2051
January21st to endNight
15%
804
11%
2603
3%
804
26%
804
12%
1957
February1st to 10thNight
15%
720
8%
2340
2%
720
22%
720
8%
1822
February11th to 20thNight
12%
703
9%
2276
2%
700
21%
700
9%
1736
February21st to endNight
19%
592
14%
1830
5%
592
29%
592
16%
1322
March1st to 10thNight
16%
719
14%
2073
4%
719
25%
719
13%
1596
March11th to 20thNight
27%
720
14%
1980
6%
720
33%
720
18%
1437
March21st to endNight
25%
737
16%
2123
6%
737
35%
737
18%
1547
April1st to 10thNight
22%
540
13%
1800
7%
540
30%
540
12%
1336
April11th to 20thNight
28%
534
16%
1776
10%
534
36%
534
17%
1265
April21st to endNight
30%
540
14%
1648
7%
540
37%
540
16%
1210
May1st to 10thNight
25%
540
14%
1481
6%
540
31%
540
16%
1144
May11th to 20thNight
34%
532
14%
1417
9%
532
38%
532
19%
1067
May21st to endNight
30%
583
9%
1551
4%
582
34%
582
17%
1188
June1st to 10thNight
31%
540
8%
1440
5%
540
33%
540
15%
1153
June11th to 20thNight
35%
540
10%
1440
6%
540
38%
540
18%
1086
June21st to endNight
27%
540
4%
1440
3%
540
28%
540
12%
1209
July1st to 10thNight
40%
526
7%
1401
5%
526
41%
526
17%
1091
July11th to 20thNight
35%
522
7%
1392
5%
522
36%
522
14%
1128
July21st to endNight
36%
590
8%
1486
7%
558
36%
558
14%
1193
August1st to 10thNight
44%
538
9%
1571
6%
534
45%
534
17%
1174
August11th to 20thNight
42%
532
12%
1596
10%
532
45%
532
18%
1172
August21st to endNight
48%
594
16%
1948
13%
594
52%
594
21%
1283
September1st to 10thNight
45%
540
15%
1800
12%
540
50%
540
22%
1173
September11th to 20thNight
39%
540
19%
1800
15%
540
46%
540
22%
1170
September21st to endNight
33%
686
17%
2066
9%
686
40%
686
20%
1449
October1st to 10thNight
37%
720
18%
2160
9%
720
44%
720
24%
1418
October11th to 20thNight
32%
720
18%
2160
8%
720
40%
720
21%
1486
October21st to endNight
21%
823
14%
2438
6%
823
28%
823
15%
1817
November1st to 10thNight
24%
830
14%
2463
5%
830
32%
830
16%
1835
November11th to 20thNight
21%
850
13%
2660
6%
850
29%
850
14%
1965
November21st to endNight
18%
850
10%
2660
3%
850
25%
850
12%
1996
December1st to 10thNight
15%
850
9%
2660
2%
850
23%
850
10%
2090
December11th to 20thNight
11%
850
9%
3236
1%
849
19%
849
8%
2604
December21st to endNight
13%
923
5%
4837
1%
907
21%
907
6%
3633

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
23%9%36%6%35%5%5%7%28%
74744
Night
24%10%46%5%3445%7%29%
75076
TransparencyDay
55%7%12%17%9%1
74447
Night
56%6%12%17%8%1
74908
SeeingDay
28%10%28%24%8%1
16313
Night
29%11%28%23%8%1
24060

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 10thDay
19%11%48%7%45%6%5%6%23%
1516
11th to 20thDay
23%12%48%7%3345%7%24%
1481
21st to endDay
15%9%47%6%46%6%8%8%28%
1750
February1st to 10thDay
22%10%45%6%46%5%5%7%26%
1620
11th to 20thDay
19%10%48%6%45%6%5%5%28%
1573
21st to endDay
13%12%46%6%35%5%6%6%34%
1426
March1st to 10thDay
17%10%47%7%346%6%7%28%
1881
11th to 20thDay
17%9%36%7%5%6%5%6%7%31%
1980
21st to endDay
18%10%47%6%46%45%6%30%
2232
April1st to 10thDay
27%8%35%5%36%446%29%
2160
11th to 20thDay
24%9%36%42435%6%32%
2134
21st to endDay
26%9%35%5%345%5%6%29%
2308
May1st to 10thDay
29%10%36%5%35%46%6%23%
2479
11th to 20thDay
25%10%47%5%34446%29%
2478
21st to endDay
26%11%36%6%34447%25%
2724
June1st to 10thDay
31%9%36%5%345%5%7%21%
2520
11th to 20thDay
26%9%36%5%345%5%6%29%
2520
21st to endDay
35%12%46%5%24345%19%
2520
July1st to 10thDay
25%9%36%5%3445%8%26%
2520
11th to 20thDay
25%12%5%6%6%3445%6%23%
2520
21st to endDay
29%10%46%6%245%5%6%23%
2745
August1st to 10thDay
20%8%46%6%35%6%5%8%30%
2355
11th to 20thDay
20%9%35%5%35%5%5%9%31%
2304
21st to endDay
19%8%35%4335%47%40%
2407
September1st to 10thDay
18%7%35%5%35%45%7%39%
2160
11th to 20thDay
21%6%25%42347%8%37%
2160
21st to endDay
20%8%25%4445%5%7%37%
1891
October1st to 10thDay
19%6%25%6%45%5%6%7%35%
1800
11th to 20thDay
21%7%35%5%345%5%7%34%
1800
21st to endDay
22%7%36%6%35%5%5%8%29%
1918
November1st to 10thDay
23%8%37%5%3445%7%31%
1613
11th to 20thDay
23%8%36%5%45%5%6%7%29%
1520
21st to endDay
19%8%36%6%45%5%7%8%28%
1520
December1st to 10thDay
24%12%46%6%35%5%5%6%24%
1520
11th to 20thDay
30%10%45%6%35%5%5%5%21%
1906
21st to endDay
23%9%6%8%6%35%446%27%
2783
January1st to 10thNight
20%13%5%7%5%345%5%7%25%
2649
11th to 20thNight
23%12%47%6%345%6%7%23%
2601
21st to endNight
17%10%5%9%6%35%5%7%7%27%
2603
February1st to 10thNight
22%10%48%6%45%5%6%8%24%
2340
11th to 20thNight
19%11%47%7%46%6%6%6%25%
2273
21st to endNight
13%12%6%9%6%3445%7%30%
1830
March1st to 10thNight
18%12%5%7%6%36%46%7%26%
2064
11th to 20thNight
20%9%35%6%36%45%7%32%
1979
21st to endNight
22%9%46%5%3445%5%34%
2123
April1st to 10thNight
29%10%35%5%4335%6%28%
1800
11th to 20thNight
26%7%35%5%45%446%32%
1776
21st to endNight
27%8%35%5%335%5%6%30%
1648
May1st to 10thNight
32%9%35%5%23346%26%
1481
11th to 20thNight
28%9%345%3445%5%31%
1416
21st to endNight
25%12%35%5%25%5%5%8%26%
1550
June1st to 10thNight
33%12%3433345%7%23%
1440
11th to 20thNight
28%9%45%5%3345%6%29%
1440
21st to endNight
35%14%46%43433421%
1440
July1st to 10thNight
25%12%46%5%33448%27%
1440
11th to 20thNight
29%16%36%5%24445%22%
1440
21st to endNight
29%13%36%43445%6%23%
1573
August1st to 10thNight
23%11%45%4345%47%30%
1582
11th to 20thNight
22%12%36%4345%5%7%31%
1596
21st to endNight
22%6%244245%5%7%40%
1948
September1st to 10thNight
19%7%245%245%48%40%
1800
11th to 20thNight
21%7%243245%5%7%40%
1800
21st to endNight
22%8%45%434346%36%
2066
October1st to 10thNight
19%425%5%35%46%7%39%
2160
11th to 20thNight
23%6%2443445%7%37%
2160
21st to endNight
25%8%35%5%35%45%6%32%
2438
November1st to 10thNight
22%9%46%5%2445%6%33%
2463
11th to 20thNight
22%9%36%6%45%5%5%6%31%
2660
21st to endNight
21%10%36%5%35%45%8%30%
2660
December1st to 10thNight
26%11%47%5%35%45%6%24%
2660
11th to 20thNight
32%12%46%5%34445%23%
3293
21st to endNight
27%10%47%5%35%5%5%6%23%
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
61%9%12%12%5%1
1517
11th to 20thDay
61%7%13%13%5%1
1481
21st to endDay
54%6%13%17%9%
1750
February1st to 10thDay
58%7%11%12%10%1
1620
11th to 20thDay
58%8%11%14%7%2
1581
21st to endDay
49%7%12%18%11%3
1426
March1st to 10thDay
54%6%11%16%11%2
1885
11th to 20thDay
49%9%12%17%10%2
1980
21st to endDay
52%7%10%18%11%2
2232
April1st to 10thDay
53%8%9%15%13%3
2160
11th to 20thDay
52%6%8%19%14%1
2134
21st to endDay
56%5%11%17%9%1
2308
May1st to 10thDay
60%6%10%14%9%1
2479
11th to 20thDay
55%7%9%20%9%
2482
21st to endDay
59%7%9%16%8%1
2724
June1st to 10thDay
62%8%10%15%5%
2520
11th to 20thDay
56%7%10%17%10%1
2520
21st to endDay
70%5%6%12%8%
2520
July1st to 10thDay
57%7%12%16%8%1
2450
11th to 20thDay
62%6%10%15%6%
2444
21st to endDay
60%8%10%16%5%1
2592
August1st to 10thDay
51%8%11%21%8%1
2341
11th to 20thDay
50%9%14%20%7%
2304
21st to endDay
44%7%14%23%11%1
2407
September1st to 10thDay
45%7%12%22%13%2
2160
11th to 20thDay
44%6%13%22%13%1
2160
21st to endDay
46%8%9%23%14%
1891
October1st to 10thDay
45%8%11%24%10%1
1800
11th to 20thDay
49%7%15%21%8%
1800
21st to endDay
55%6%12%18%9%
1918
November1st to 10thDay
53%7%12%19%8%1
1613
11th to 20thDay
54%6%13%17%9%1
1520
21st to endDay
54%6%16%15%7%1
1520
December1st to 10thDay
62%6%12%15%5%
1520
11th to 20thDay
66%5%12%11%6%
1905
21st to endDay
61%419%10%5%1
2783
January1st to 10thNight
62%6%14%15%4
2649
11th to 20thNight
62%7%14%11%5%1
2601
21st to endNight
58%6%14%16%6%
2603
February1st to 10thNight
60%8%12%11%8%1
2340
11th to 20thNight
60%6%14%12%7%2
2276
21st to endNight
54%414%18%8%2
1830
March1st to 10thNight
59%6%10%15%10%1
2073
11th to 20thNight
51%6%13%16%11%2
1980
21st to endNight
54%410%19%11%3
2123
April1st to 10thNight
57%6%9%15%11%2
1800
11th to 20thNight
52%7%9%18%13%2
1776
21st to endNight
55%5%9%18%11%1
1648
May1st to 10thNight
60%48%19%7%1
1481
11th to 20thNight
55%6%9%22%9%
1417
21st to endNight
57%7%13%16%7%1
1551
June1st to 10thNight
62%5%8%18%6%
1440
11th to 20thNight
56%5%10%15%14%
1440
21st to endNight
69%47%13%6%1
1440
July1st to 10thNight
58%6%13%16%7%
1401
11th to 20thNight
63%6%9%14%7%
1392
21st to endNight
62%7%12%15%5%
1486
August1st to 10thNight
55%6%12%21%5%
1571
11th to 20thNight
53%7%15%18%7%
1596
21st to endNight
44%8%14%24%11%
1948
September1st to 10thNight
44%6%12%24%12%1
1800
11th to 20thNight
45%5%11%24%14%1
1800
21st to endNight
50%6%9%24%12%1
2066
October1st to 10thNight
42%7%16%23%12%1
2160
11th to 20thNight
46%6%13%27%8%
2160
21st to endNight
54%6%13%17%9%
2438
November1st to 10thNight
53%8%13%17%9%
2463
11th to 20thNight
55%6%14%15%10%
2660
21st to endNight
57%6%16%15%6%
2660
December1st to 10thNight
63%6%14%13%5%
2660
11th to 20thNight
66%411%13%6%
3295
21st to endNight
63%5%14%14%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
24%19%34%19%4
370
11th to 20thDay
27%17%35%16%4
356
21st to endDay
22%14%37%23%5%
374
February1st to 10thDay
29%19%33%18%1
340
11th to 20thDay
27%18%35%18%2
336
21st to endDay
20%14%41%20%5%
280
March1st to 10thDay
21%16%41%19%3
378
11th to 20thDay
21%16%33%24%6%
420
21st to endDay
23%13%37%19%7%1
462
April1st to 10thDay
31%13%34%18%3
420
11th to 20thDay
31%10%34%18%5%1
412
21st to endDay
27%8%28%28%7%2
420
May1st to 10thDay
33%8%31%21%5%2
562
11th to 20thDay
29%5%28%31%5%2
624
21st to endDay
35%8%24%26%6%1
680
June1st to 10thDay
36%422%28%9%1
630
11th to 20thDay
29%6%23%32%9%1
630
21st to endDay
40%418%26%10%1
630
July1st to 10thDay
34%318%32%12%1
620
11th to 20thDay
35%415%30%15%1
618
21st to endDay
35%318%31%11%2
685
August1st to 10thDay
22%324%33%15%3
474
11th to 20thDay
28%424%26%13%4
439
21st to endDay
22%6%22%30%16%4
495
September1st to 10thDay
23%6%26%29%15%2
450
11th to 20thDay
25%8%25%28%12%2
450
21st to endDay
24%5%29%24%16%2
390
October1st to 10thDay
22%8%29%24%15%3
360
11th to 20thDay
22%9%30%24%14%1
360
21st to endDay
26%12%34%19%7%1
396
November1st to 10thDay
22%15%31%24%6%2
365
11th to 20thDay
28%18%31%16%6%1
370
21st to endDay
22%18%38%16%5%1
370
December1st to 10thDay
28%16%32%20%3
370
11th to 20thDay
32%22%29%15%1
370
21st to endDay
25%18%33%19%5%
407
January1st to 10thNight
29%17%33%18%3
850
11th to 20thNight
29%17%34%17%3
829
21st to endNight
22%19%37%17%5%
804
February1st to 10thNight
29%18%32%20%2
720
11th to 20thNight
25%20%38%14%2
703
21st to endNight
19%14%39%21%7%
592
March1st to 10thNight
22%16%40%19%3
720
11th to 20thNight
25%13%29%24%9%1
720
21st to endNight
25%13%31%24%7%
737
April1st to 10thNight
33%11%27%23%5%
540
11th to 20thNight
29%7%31%26%6%1
534
21st to endNight
33%6%24%27%9%1
540
May1st to 10thNight
35%5%28%21%9%2
540
11th to 20thNight
32%423%27%11%3
532
21st to endNight
31%5%27%28%8%1
583
June1st to 10thNight
40%319%29%8%1
540
11th to 20thNight
33%418%33%11%1
540
21st to endNight
41%319%23%13%1
540
July1st to 10thNight
32%315%34%15%1
526
11th to 20thNight
36%315%29%17%
522
21st to endNight
37%414%26%18%1
590
August1st to 10thNight
27%415%33%19%2
538
11th to 20thNight
26%318%33%18%2
532
21st to endNight
25%418%28%22%3
594
September1st to 10thNight
21%424%31%18%2
540
11th to 20thNight
24%6%24%28%16%2
540
21st to endNight
26%7%26%28%11%2
686
October1st to 10thNight
21%7%29%31%11%2
720
11th to 20thNight
26%9%29%25%9%2
720
21st to endNight
30%12%32%19%6%
823
November1st to 10thNight
27%13%29%23%6%1
830
11th to 20thNight
27%17%30%19%7%
850
21st to endNight
28%16%32%18%4
850
December1st to 10thNight
32%15%32%15%5%
850
11th to 20thNight
31%20%33%14%2
850
21st to endNight
29%16%34%16%41
935
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