Michigan City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Michigan City clear sky chart from 2005-11-05 to 2017-09-17.

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
33%
15945
15%
46829
9%
15903
38%
15903
17%
33343

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
14%
900
8%
2506
3%
895
18%
895
9%
2071
January16th to endNight
15%
960
8%
2688
3%
960
19%
960
9%
2214
February1st to 15thNight
19%
743
9%
2163
3%
743
24%
743
12%
1693
February16th to endNight
21%
631
14%
1893
5%
631
29%
631
12%
1443
March1st to 15thNight
23%
720
12%
2160
7%
720
27%
720
14%
1600
March16th to endNight
29%
677
16%
2030
9%
677
36%
677
17%
1462
April1st to 15thNight
29%
539
13%
1797
11%
539
35%
539
16%
1254
April16th to endNight
29%
540
19%
1697
7%
540
41%
540
17%
1147
May1st to 15thNight
36%
540
15%
1620
9%
540
41%
540
18%
1129
May16th to endNight
45%
562
16%
1536
9%
561
51%
561
25%
1003
June1st to 15thNight
49%
540
16%
1440
9%
540
54%
540
29%
902
June16th to endNight
46%
540
14%
1440
8%
540
50%
540
27%
942
July1st to 15thNight
61%
510
17%
1360
13%
510
64%
510
35%
824
July16th to endNight
59%
564
21%
1417
15%
531
65%
531
36%
847
August1st to 15thNight
66%
539
21%
1574
18%
536
69%
536
34%
913
August16th to endNight
62%
573
20%
1908
18%
573
67%
573
29%
1104
September1st to 15thNight
57%
579
25%
1839
23%
579
61%
579
29%
1083
September16th to endNight
54%
665
25%
1837
17%
665
60%
665
31%
1137
October1st to 15thNight
44%
660
24%
1848
18%
660
48%
660
27%
1187
October16th to endNight
24%
704
14%
2273
8%
704
32%
704
15%
1598
November1st to 15thNight
28%
700
18%
2276
15%
700
35%
700
17%
1553
November16th to endNight
19%
720
12%
2340
7%
720
25%
720
10%
1778
December1st to 15thNight
12%
879
6%
2499
2%
879
15%
879
7%
2102
December16th to endNight
10%
960
6%
2688
1%
960
14%
960
6%
2357

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%8%46%5%3445%7%35%
47954
Night
15%10%47%5%34446%34%
46997
Cloud CoverDay
13%8%46%5%3445%7%35%
47963
Night
15%10%46%5%34446%34%
47002
TransparencyDay
47%6%12%20%11%1
47640
Night
50%6%11%19%11%1
46829
SeeingDay
14%13%23%26%16%4
5946
Night
17%21%22%25%12%1
15949

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
15%19%8%11%8%4333415%
1432
16th to endDay
13%18%9%13%8%5%432416%
1536
February1st to 15thDay
14%16%7%10%8%35%34420%
1696
16th to endDay
13%13%7%10%7%3444426%
1580
March1st to 15thDay
16%10%5%8%6%245%5%6%27%
1790
16th to endDay
16%9%36%6%24446%34%
2203
April1st to 15thDay
17%9%45%5%2435%6%35%
2151
16th to endDay
16%7%35%425%448%37%
2262
May1st to 15thDay
17%8%25%435%46%6%35%
2331
16th to endDay
10%6%25%5%36%5%5%8%40%
2578
June1st to 15thDay
10%426%5%2445%7%45%
2520
16th to endDay
8%325%5%35%5%6%9%42%
2520
July1st to 15thDay
6%425%425%5%5%8%47%
2520
16th to endDay
5%324435%5%7%10%47%
2655
August1st to 15thDay
6%425%5%345%6%9%46%
2376
16th to endDay
9%42443446%8%46%
2292
September1st to 15thDay
12%5%244345%5%7%45%
2109
16th to endDay
10%6%345%345%5%8%42%
1829
October1st to 15thDay
17%6%34433446%40%
1779
16th to endDay
21%9%36%435%5%5%6%29%
1598
November1st to 15thDay
17%10%35%424346%36%
1582
16th to endDay
18%15%6%9%5%35%335%23%
1620
December1st to 15thDay
18%17%10%10%8%3323416%
1459
16th to endDay
21%19%6%9%6%24335%16%
1536
January1st to 15thNight
19%14%7%10%7%33435%19%
2506
16th to endNight
15%15%8%11%7%5%5%43419%
2688
February1st to 15thNight
17%12%6%8%7%35%35%425%
2161
16th to endNight
17%12%5%9%7%34345%26%
1893
March1st to 15thNight
16%12%6%7%423345%30%
2147
16th to endNight
17%9%37%43445%7%32%
2030
April1st to 15thNight
17%9%45%425%446%33%
1797
16th to endNight
17%8%25%5%43435%39%
1697
May1st to 15thNight
18%7%25%5%3445%7%34%
1620
16th to endNight
11%5%15%5%2445%6%44%
1534
June1st to 15thNight
9%425%5%2435%8%47%
1440
16th to endNight
8%415%5%45%5%7%9%40%
1440
July1st to 15thNight
6%3145%245%7%8%51%
1440
16th to endNight
6%3234245%7%10%48%
1513
August1st to 15thNight
44235%25%46%10%50%
1583
16th to endNight
9%4135%3445%7%50%
1908
September1st to 15thNight
13%424323446%48%
1839
16th to endNight
11%5%24434447%47%
1837
October1st to 15thNight
15%6%2442345%5%45%
1848
16th to endNight
25%8%35%423435%33%
2273
November1st to 15thNight
16%12%46%323445%37%
2276
16th to endNight
19%15%5%8%5%33445%24%
2340
December1st to 15thNight
21%19%8%10%6%2323417%
2499
16th to endNight
22%18%8%11%7%3333313%
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
16%17%8%10%8%4434416%
1432
16th to endDay
13%18%10%11%8%5%5%32416%
1536
February1st to 15thDay
14%17%6%9%7%4443421%
1696
16th to endDay
14%13%7%11%7%24435%26%
1580
March1st to 15thDay
17%11%5%8%6%2445%6%27%
1800
16th to endDay
17%9%36%5%3435%6%34%
2202
April1st to 15thDay
18%9%45%424446%34%
2151
16th to endDay
16%8%2442445%7%37%
2262
May1st to 15thDay
18%8%25%5%35%447%34%
2331
16th to endDay
11%6%25%5%35%5%6%8%40%
2578
June1st to 15thDay
10%425%5%24447%45%
2520
16th to endDay
9%4245%35%5%6%9%41%
2520
July1st to 15thDay
6%5%25%435%5%5%8%47%
2520
16th to endDay
5%324436%5%6%10%46%
2655
August1st to 15thDay
6%4245%35%5%7%9%46%
2376
16th to endDay
10%425%5%345%6%8%45%
2292
September1st to 15thDay
12%4245%346%5%6%44%
2109
16th to endDay
10%6%25%5%3445%8%41%
1829
October1st to 15thDay
17%7%1443345%6%40%
1779
16th to endDay
21%8%36%5%235%5%6%30%
1598
November1st to 15thDay
18%10%35%434347%36%
1582
16th to endDay
18%15%5%8%5%34335%24%
1620
December1st to 15thDay
18%17%9%11%7%33225%16%
1459
16th to endDay
22%18%6%10%5%34345%17%
1536
January1st to 15thNight
19%14%7%9%6%3343420%
2506
16th to endNight
15%15%8%10%7%45%445%19%
2688
February1st to 15thNight
17%13%5%8%7%35%445%25%
2154
16th to endNight
17%12%6%8%6%34335%27%
1893
March1st to 15thNight
17%12%6%7%423345%31%
2160
16th to endNight
16%9%36%5%25%45%7%33%
2030
April1st to 15thNight
18%9%36%5%24446%34%
1797
16th to endNight
17%7%25%5%34345%39%
1697
May1st to 15thNight
19%7%35%434447%34%
1619
16th to endNight
12%425%5%2445%7%44%
1534
June1st to 15thNight
9%4245%3345%8%47%
1440
16th to endNight
7%425%5%45%5%7%8%41%
1440
July1st to 15thNight
6%3135%25%5%7%9%51%
1440
16th to endNight
6%313425%6%7%9%49%
1513
August1st to 15thNight
44235%245%7%9%50%
1583
16th to endNight
10%423444447%49%
1908
September1st to 15thNight
13%424423347%48%
1839
16th to endNight
10%5%24434448%47%
1837
October1st to 15thNight
15%5%2442245%5%45%
1848
16th to endNight
24%9%25%424335%34%
2273
November1st to 15thNight
17%11%36%423345%37%
2276
16th to endNight
19%15%48%6%23336%25%
2340
December1st to 15thNight
20%18%8%10%6%2343417%
2499
16th to endNight
22%18%7%10%9%3333413%
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
71%411%7%4
1433
16th to endDay
70%5%9%10%3
1536
February1st to 15thDay
65%410%12%41
1698
16th to endDay
60%5%12%16%4
1580
March1st to 15thDay
55%7%13%15%7%
1800
16th to endDay
50%5%13%23%5%
2203
April1st to 15thDay
49%5%9%21%13%
2151
16th to endDay
45%7%12%18%11%4
2262
May1st to 15thDay
49%7%11%22%8%
2331
16th to endDay
41%7%12%23%13%1
2582
June1st to 15thDay
37%6%10%24%19%1
2520
16th to endDay
36%7%15%20%17%1
2520
July1st to 15thDay
33%8%12%25%18%2
2371
16th to endDay
31%9%17%24%15%2
2488
August1st to 15thDay
31%8%14%26%16%2
2361
16th to endDay
34%7%14%23%16%3
2292
September1st to 15thDay
36%7%13%22%18%3
2109
16th to endDay
38%6%10%26%16%1
1829
October1st to 15thDay
43%6%11%22%14%1
1779
16th to endDay
53%6%14%18%7%1
1598
November1st to 15thDay
47%5%10%19%14%1
1582
16th to endDay
61%5%11%16%4
1620
December1st to 15thDay
71%5%8%11%3
1459
16th to endDay
69%6%11%8%3
1536
January1st to 15thNight
66%6%10%11%4
2506
16th to endNight
65%6%12%11%3
2688
February1st to 15thNight
60%5%11%15%6%
2163
16th to endNight
59%411%18%5%
1893
March1st to 15thNight
55%5%11%16%8%1
2160
16th to endNight
50%6%12%20%7%1
2030
April1st to 15thNight
51%5%10%17%15%
1797
16th to endNight
47%5%8%19%15%3
1697
May1st to 15thNight
48%6%11%22%10%
1620
16th to endNight
38%7%14%21%15%2
1536
June1st to 15thNight
33%6%12%27%18%1
1440
16th to endNight
36%7%16%21%15%1
1440
July1st to 15thNight
28%8%13%26%20%3
1360
16th to endNight
28%7%15%25%18%4
1417
August1st to 15thNight
27%8%14%26%21%1
1574
16th to endNight
32%7%10%24%19%5%
1908
September1st to 15thNight
34%5%10%24%20%5%
1839
16th to endNight
35%5%8%26%21%2
1837
October1st to 15thNight
38%5%9%25%19%1
1848
16th to endNight
52%412%21%8%1
2273
November1st to 15thNight
48%5%8%19%14%2
2276
16th to endNight
61%312%17%4
2340
December1st to 15thNight
70%5%8%11%3
2499
16th to endNight
75%5%7%9%2
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
23%16%33%18%7%
90
16th to endDay
20%8%44%21%31
96
February1st to 15thDay
17%28%38%12%2
90
16th to endDay
14%17%32%23%12%
81
March1st to 15thDay
28%13%35%20%2
90
16th to endDay
25%18%25%20%9%
277
April1st to 15thDay
24%17%28%21%7%1
270
16th to endDay
18%18%28%18%11%4
270
May1st to 15thDay
21%18%23%21%11%2
288
16th to endDay
13%16%26%25%15%2
478
June1st to 15thDay
10%14%21%34%16%3
495
16th to endDay
10%13%28%31%13%2
495
July1st to 15thDay
6%9%22%33%21%7%
475
16th to endDay
6%13%14%34%21%8%
515
August1st to 15thDay
8%6%11%30%28%13%
349
16th to endDay
11%6%15%27%28%9%
332
September1st to 15thDay
11%7%10%30%29%9%
315
16th to endDay
12%12%10%29%25%9%
259
October1st to 15thDay
15%8%24%25%22%3
219
16th to endDay
27%8%35%27%2
96
November1st to 15thDay
10%12%22%28%24%2
90
16th to endDay
34%8%38%13%4
90
December1st to 15thDay
23%24%30%18%3
90
16th to endDay
26%28%42%3
96
January1st to 15thNight
20%30%29%17%2
900
16th to endNight
19%26%29%21%2
960
February1st to 15thNight
21%25%28%19%4
746
16th to endNight
19%24%27%21%6%
631
March1st to 15thNight
17%24%29%21%6%
720
16th to endNight
18%21%25%26%7%
677
April1st to 15thNight
19%23%23%25%6%
539
16th to endNight
17%21%25%22%9%2
540
May1st to 15thNight
20%18%20%28%10%1
540
16th to endNight
10%19%18%32%18%1
563
June1st to 15thNight
10%17%15%37%17%
540
16th to endNight
8%18%19%31%21%
540
July1st to 15thNight
6%12%13%37%26%3
510
16th to endNight
7%17%9%33%26%4
564
August1st to 15thNight
6%10%9%38%29%5%
539
16th to endNight
8%9%12%33%29%6%
573
September1st to 15thNight
13%11%11%32%26%4
579
16th to endNight
12%12%13%27%29%4
665
October1st to 15thNight
16%14%18%30%16%2
660
16th to endNight
26%19%27%20%6%
704
November1st to 15thNight
20%22%26%18%11%
700
16th to endNight
24%30%22%18%4
720
December1st to 15thNight
28%27%25%15%2
879
16th to endNight
25%28%29%15%1
960
Page generated at 2017-09-18 08:38:29. Version ac04

Copyright 2017 A. Danko


Michigan City Clear Sky Chart | Charts Home