South Haven Pier
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Haven Pier clear sky chart from 2005-11-05 to 2017-09-19.

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
32%
15977
14%
46843
9%
15935
37%
15935
18%
33947

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
10%
900
5%
2506
1%
895
14%
895
7%
2165
January16th to endNight
12%
960
4%
2688
1%
960
14%
960
6%
2369
February1st to 15thNight
14%
732
6%
2188
2%
732
19%
732
7%
1830
February16th to endNight
18%
631
11%
1893
5%
631
25%
631
10%
1512
March1st to 15thNight
26%
720
14%
2154
9%
720
30%
720
16%
1565
March16th to endNight
28%
702
17%
2046
10%
702
35%
702
20%
1431
April1st to 15thNight
27%
539
14%
1797
9%
539
35%
539
18%
1239
April16th to endNight
35%
540
20%
1668
12%
540
43%
540
22%
1087
May1st to 15thNight
34%
540
15%
1620
9%
540
40%
540
21%
1110
May16th to endNight
44%
562
15%
1542
10%
561
48%
561
30%
1008
June1st to 15thNight
51%
540
16%
1440
10%
540
55%
540
35%
903
June16th to endNight
52%
540
15%
1440
10%
540
56%
540
32%
928
July1st to 15thNight
60%
510
17%
1360
11%
510
63%
510
41%
795
July16th to endNight
64%
564
21%
1417
15%
531
67%
531
40%
833
August1st to 15thNight
66%
539
22%
1581
18%
536
69%
536
37%
903
August16th to endNight
61%
573
20%
1866
19%
573
65%
573
32%
1077
September1st to 15thNight
57%
592
26%
1852
23%
592
63%
592
33%
1067
September16th to endNight
52%
673
23%
1858
16%
673
56%
673
31%
1172
October1st to 15thNight
43%
660
23%
1839
16%
660
49%
660
27%
1212
October16th to endNight
20%
704
12%
2288
7%
704
28%
704
13%
1668
November1st to 15thNight
27%
700
18%
2276
13%
700
34%
700
17%
1592
November16th to endNight
18%
720
10%
2340
7%
720
23%
720
10%
1870
December1st to 15thNight
9%
876
4%
2496
1%
876
12%
876
6%
2214
December16th to endNight
8%
960
5%
2688
1%
960
11%
960
5%
2397

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
13%9%46%5%34447%35%
47978
Night
16%11%5%7%5%24345%31%
47011
Cloud CoverDay
13%9%47%5%3445%7%35%
47987
Night
16%11%5%7%5%23446%31%
47016
TransparencyDay
49%411%21%11%1
47664
Night
54%310%18%10%1
46843
SeeingDay
16%12%29%23%13%5%
5974
Night
22%11%25%25%11%1
15981

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
18%17%8%13%8%4444410%
1432
16th to endDay
15%20%12%14%10%343239%
1536
February1st to 15thDay
13%16%8%15%11%4432415%
1669
16th to endDay
15%13%7%11%8%3444421%
1580
March1st to 15thDay
14%10%5%9%5%35%45%7%27%
1796
16th to endDay
15%8%36%5%2445%6%36%
2190
April1st to 15thDay
18%11%34434346%33%
2151
16th to endDay
16%5%25%4245%5%7%38%
2291
May1st to 15thDay
15%6%36%6%35%5%5%7%35%
2331
16th to endDay
8%5%25%5%35%5%5%8%44%
2572
June1st to 15thDay
9%4245%245%5%8%46%
2520
16th to endDay
8%4245%345%6%9%45%
2520
July1st to 15thDay
6%31432436%10%51%
2520
16th to endDay
6%324435%46%9%50%
2655
August1st to 15thDay
7%4244345%6%9%47%
2369
16th to endDay
10%4244235%48%48%
2333
September1st to 15thDay
12%425%5%2445%7%45%
2094
16th to endDay
11%6%35%4335%5%9%41%
1848
October1st to 15thDay
17%7%36%5%2344439%
1788
16th to endDay
26%8%36%5%35%446%25%
1584
November1st to 15thDay
17%12%35%434335%35%
1582
16th to endDay
22%21%5%9%423335%18%
1620
December1st to 15thDay
18%26%12%10%5%2322312%
1461
16th to endDay
22%22%11%10%42233411%
1536
January1st to 15thNight
21%18%7%12%9%3333313%
2506
16th to endNight
15%17%12%14%10%3433311%
2688
February1st to 15thNight
14%17%8%14%10%3322317%
2186
16th to endNight
17%15%6%11%7%3334421%
1893
March1st to 15thNight
16%11%49%5%2334432%
2141
16th to endNight
16%8%36%6%24446%35%
2046
April1st to 15thNight
18%10%45%42445%7%32%
1797
16th to endNight
17%6%25%42445%6%39%
1668
May1st to 15thNight
17%6%36%7%3345%6%35%
1620
16th to endNight
11%6%25%5%2445%8%42%
1540
June1st to 15thNight
10%5%25%5%2345%8%46%
1440
16th to endNight
7%4245%38%6%5%9%42%
1440
July1st to 15thNight
5%315%43446%8%50%
1440
16th to endNight
7%3144145%6%10%50%
1513
August1st to 15thNight
5%4145%445%5%8%50%
1590
16th to endNight
10%5%2443435%7%49%
1866
September1st to 15thNight
13%414324346%50%
1852
16th to endNight
11%6%25%6%33446%44%
1858
October1st to 15thNight
20%5%14423445%42%
1839
16th to endNight
27%9%36%5%2333429%
2288
November1st to 15thNight
18%13%45%323435%33%
2276
16th to endNight
22%20%6%8%423235%20%
2340
December1st to 15thNight
24%23%10%9%42322310%
2496
16th to endNight
24%21%10%11%5%332339%
2688

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
18%17%8%12%9%4443412%
1432
16th to endDay
15%21%11%13%11%25%32210%
1536
February1st to 15thDay
13%16%8%15%12%4433315%
1669
16th to endDay
15%13%7%13%6%44446%19%
1580
March1st to 15thDay
14%12%5%8%5%36%348%26%
1806
16th to endDay
16%9%36%5%2445%6%34%
2189
April1st to 15thDay
19%11%45%5%24347%33%
2151
16th to endDay
16%6%35%4235%5%6%39%
2291
May1st to 15thDay
16%6%36%5%345%6%6%35%
2331
16th to endDay
9%425%5%35%5%5%8%43%
2572
June1st to 15thDay
10%425%4245%5%7%46%
2520
16th to endDay
8%425%42446%9%45%
2520
July1st to 15thDay
6%314335%36%11%49%
2520
16th to endDay
6%314425%46%10%49%
2655
August1st to 15thDay
7%3245%345%6%9%47%
2369
16th to endDay
11%4245%3335%8%47%
2333
September1st to 15thDay
11%5%245%2445%7%44%
2094
16th to endDay
11%6%25%5%2446%10%41%
1848
October1st to 15thDay
18%7%26%5%34435%39%
1788
16th to endDay
27%7%36%5%345%45%25%
1584
November1st to 15thDay
17%11%45%434435%35%
1582
16th to endDay
21%20%6%9%5%23335%18%
1620
December1st to 15thDay
18%25%12%10%6%2223212%
1461
16th to endDay
22%22%10%10%5%2323312%
1536
January1st to 15thNight
21%18%8%12%8%3433314%
2506
16th to endNight
15%17%13%14%10%3423311%
2688
February1st to 15thNight
14%17%8%14%9%4323318%
2179
16th to endNight
17%15%7%10%7%3333422%
1893
March1st to 15thNight
17%10%49%5%23345%32%
2154
16th to endNight
17%7%46%5%25%447%34%
2046
April1st to 15thNight
18%10%36%42445%7%32%
1797
16th to endNight
17%7%24424446%39%
1668
May1st to 15thNight
17%6%36%7%3345%7%35%
1619
16th to endNight
11%5%36%43445%8%42%
1540
June1st to 15thNight
11%415%5%2445%9%45%
1440
16th to endNight
7%425%5%26%6%5%8%43%
1440
July1st to 15thNight
5%325%5%2446%9%51%
1440
16th to endNight
6%3234245%5%11%50%
1513
August1st to 15thNight
5%3245%35%6%5%7%50%
1590
16th to endNight
10%5%24433347%49%
1866
September1st to 15thNight
12%414323446%51%
1852
16th to endNight
11%5%26%5%23446%45%
1858
October1st to 15thNight
20%5%24323445%42%
1839
16th to endNight
26%10%46%423335%29%
2288
November1st to 15thNight
18%14%46%32344434%
2276
16th to endNight
21%19%7%8%42323421%
2340
December1st to 15thNight
24%24%9%9%42322411%
2496
16th to endNight
24%22%10%10%6%233339%
2688

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
76%49%7%1
1433
16th to endDay
81%28%5%2
1536
February1st to 15thDay
76%27%10%2
1671
16th to endDay
66%410%13%4
1580
March1st to 15thDay
58%314%16%7%
1806
16th to endDay
49%413%25%6%1
2190
April1st to 15thDay
52%39%21%13%
2151
16th to endDay
44%413%20%13%3
2291
May1st to 15thDay
47%412%24%9%1
2331
16th to endDay
37%5%13%28%13%1
2576
June1st to 15thDay
35%412%27%18%
2520
16th to endDay
34%416%24%18%1
2520
July1st to 15thDay
30%413%28%20%2
2371
16th to endDay
30%5%14%28%18%2
2488
August1st to 15thDay
32%5%12%31%14%1
2354
16th to endDay
35%414%26%16%2
2333
September1st to 15thDay
37%411%25%18%3
2094
16th to endDay
38%311%31%13%
1848
October1st to 15thDay
48%38%24%13%
1788
16th to endDay
58%314%16%5%
1584
November1st to 15thDay
52%310%21%10%1
1582
16th to endDay
70%29%14%2
1620
December1st to 15thDay
79%26%8%2
1461
16th to endDay
77%39%7%1
1536
January1st to 15thNight
76%18%8%3
2506
16th to endNight
79%210%6%1
2688
February1st to 15thNight
72%28%11%4
2188
16th to endNight
66%29%15%4
1893
March1st to 15thNight
54%412%18%9%1
2154
16th to endNight
50%412%23%7%1
2046
April1st to 15thNight
51%39%20%14%
1797
16th to endNight
45%310%20%15%4
1668
May1st to 15thNight
48%311%23%10%2
1620
16th to endNight
39%413%23%15%2
1542
June1st to 15thNight
35%411%28%18%1
1440
16th to endNight
37%6%15%23%16%1
1440
July1st to 15thNight
28%5%13%28%20%3
1360
16th to endNight
28%6%15%25%20%4
1417
August1st to 15thNight
30%5%13%28%20%2
1581
16th to endNight
34%410%27%18%4
1866
September1st to 15thNight
33%39%28%20%3
1852
16th to endNight
38%39%28%17%1
1858
October1st to 15thNight
43%38%26%16%
1839
16th to endNight
58%212%18%7%
2288
November1st to 15thNight
53%39%19%12%1
2276
16th to endNight
67%211%15%2
2340
December1st to 15thNight
79%27%7%2
2496
16th to endNight
80%28%7%
2688

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
22%25%34%16%1
90
16th to endDay
32%16%37%9%4
96
February1st to 15thDay
21%43%25%7%2
90
16th to endDay
22%27%29%17%3
81
March1st to 15thDay
29%23%31%12%3
96
16th to endDay
28%15%26%18%8%2
288
April1st to 15thDay
27%14%32%16%7%
270
16th to endDay
22%14%30%17%11%3
270
May1st to 15thDay
22%15%29%18%9%4
288
16th to endDay
12%15%36%22%9%5%
472
June1st to 15thDay
11%7%39%25%11%4
495
16th to endDay
12%11%35%24%12%3
495
July1st to 15thDay
6%8%33%30%13%8%
475
16th to endDay
7%428%35%15%8%
515
August1st to 15thDay
8%224%24%27%11%
342
16th to endDay
18%418%28%20%9%
332
September1st to 15thDay
13%5%20%27%23%9%
315
16th to endDay
14%8%17%25%25%9%
266
October1st to 15thDay
19%11%21%28%15%3
236
16th to endDay
30%23%33%11%1
96
November1st to 15thDay
14%18%27%25%11%2
90
16th to endDay
36%25%27%8%1
90
December1st to 15thDay
34%33%18%10%3
90
16th to endDay
35%35%25%31
96
January1st to 15thNight
31%19%28%16%4
900
16th to endNight
25%17%31%22%2
960
February1st to 15thNight
23%18%32%19%5%
735
16th to endNight
25%17%30%22%4
631
March1st to 15thNight
24%16%26%24%7%
720
16th to endNight
20%11%33%25%7%1
702
April1st to 15thNight
23%14%29%25%6%
539
16th to endNight
21%10%29%28%7%2
540
May1st to 15thNight
20%9%28%30%9%1
540
16th to endNight
15%6%26%34%16%
563
June1st to 15thNight
13%324%39%18%
540
16th to endNight
10%425%36%22%1
540
July1st to 15thNight
8%121%39%25%3
510
16th to endNight
7%318%37%28%3
564
August1st to 15thNight
7%115%44%25%5%
539
16th to endNight
11%5%14%34%30%4
573
September1st to 15thNight
16%416%31%26%5%
592
16th to endNight
16%6%18%29%23%5%
673
October1st to 15thNight
23%6%22%29%15%2
660
16th to endNight
34%14%25%17%6%
704
November1st to 15thNight
26%12%27%22%10%
700
16th to endNight
34%18%24%17%4
720
December1st to 15thNight
36%17%28%15%2
876
16th to endNight
35%18%29%13%2
960
Page generated at 2017-09-20 04:49:45. Version ac04

Copyright 2017 A. Danko


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