Lansing
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lansing clear sky chart from 2005-11-05 to

2017-09-12
.

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
37%
15922
15%
46741
10%
15880
42%
15880
20%
32925

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
15%
900
8%
2506
4%
895
20%
895
10%
2059
January16th to endNight
20%
920
7%
2648
3%
920
24%
920
10%
2183
February1st to 15thNight
18%
701
9%
2226
3%
701
25%
701
10%
1742
February16th to endNight
23%
631
13%
1893
5%
631
31%
631
14%
1414
March1st to 15thNight
30%
720
15%
2106
10%
720
34%
720
19%
1505
March16th to endNight
34%
768
18%
2112
10%
768
40%
768
21%
1485
April1st to 15thNight
28%
543
13%
1794
9%
543
34%
543
18%
1237
April16th to endNight
35%
540
19%
1620
9%
540
44%
540
24%
1066
May1st to 15thNight
35%
540
14%
1620
7%
540
42%
540
22%
1116
May16th to endNight
48%
562
16%
1614
11%
561
53%
561
29%
1039
June1st to 15thNight
52%
540
15%
1440
11%
540
56%
540
32%
916
June16th to endNight
56%
540
15%
1440
11%
540
59%
540
33%
909
July1st to 15thNight
65%
510
17%
1360
14%
510
68%
510
42%
810
July16th to endNight
67%
564
20%
1450
17%
531
69%
531
41%
852
August1st to 15thNight
67%
539
20%
1609
16%
536
70%
536
36%
938
August16th to endNight
61%
573
21%
1782
17%
573
65%
573
32%
1051
September1st to 15thNight
60%
626
26%
1863
22%
626
64%
626
35%
1083
September16th to endNight
58%
657
22%
1815
16%
657
61%
657
33%
1120
October1st to 15thNight
45%
660
20%
1871
16%
660
50%
660
27%
1249
October16th to endNight
27%
704
14%
2244
8%
704
36%
704
17%
1614
November1st to 15thNight
36%
700
19%
2276
17%
700
41%
700
20%
1519
November16th to endNight
26%
720
13%
2340
8%
720
32%
720
14%
1749
December1st to 15thNight
17%
804
7%
2424
2%
804
21%
804
10%
1962
December16th to endNight
15%
960
8%
2688
2%
960
20%
960
8%
2307

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%8%46%6%35%45%7%33%
47917
Night
15%9%46%5%34446%34%
46914
Cloud CoverDay
13%8%47%6%35%5%5%7%33%
47926
Night
14%9%47%5%34446%34%
46919
TransparencyDay
49%6%11%20%11%1
47608
Night
49%5%11%20%11%1
46741
SeeingDay
17%6%26%24%16%7%
5914
Night
19%7%28%30%12%1
15926

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
17%16%7%9%8%5%5%5%45%15%
1432
16th to endDay
14%19%8%10%9%45%44414%
1575
February1st to 15thDay
13%13%6%11%9%5%6%33420%
1633
16th to endDay
14%13%5%11%7%35%5%36%21%
1580
March1st to 15thDay
15%9%48%7%35%45%8%28%
1844
16th to endDay
17%10%47%6%2435%6%31%
2118
April1st to 15thDay
20%10%46%5%34445%30%
2157
16th to endDay
16%6%26%5%25%447%37%
2340
May1st to 15thDay
19%7%36%5%25%35%6%34%
2331
16th to endDay
13%5%35%5%3446%7%39%
2498
June1st to 15thDay
11%435%5%35%5%5%7%42%
2520
16th to endDay
9%426%6%45%6%7%9%38%
2520
July1st to 15thDay
7%4144245%7%9%46%
2520
16th to endDay
8%425%5%26%6%7%8%41%
2618
August1st to 15thDay
10%425%6%35%5%7%8%40%
2340
16th to endDay
11%6%25%5%35%5%6%8%40%
2417
September1st to 15thDay
12%5%145%245%5%8%42%
2005
16th to endDay
12%5%36%5%25%46%9%39%
1815
October1st to 15thDay
15%6%36%5%44446%38%
1758
16th to endDay
22%9%46%6%345%35%30%
1625
November1st to 15thDay
14%10%35%5%24436%38%
1582
16th to endDay
17%15%5%6%5%34446%25%
1620
December1st to 15thDay
15%14%9%12%6%34345%19%
1533
16th to endDay
19%19%8%9%5%3434416%
1536
January1st to 15thNight
20%14%6%9%7%3443419%
2506
16th to endNight
13%13%9%11%8%5%5%446%17%
2648
February1st to 15thNight
16%13%6%9%7%45%44424%
2224
16th to endNight
15%11%48%8%35%5%47%25%
1893
March1st to 15thNight
15%11%47%5%23446%34%
2093
16th to endNight
15%7%36%5%25%5%5%7%35%
2112
April1st to 15thNight
18%9%35%5%235%5%6%33%
1794
16th to endNight
16%7%25%42445%6%39%
1620
May1st to 15thNight
19%7%25%5%3445%7%34%
1620
16th to endNight
12%5%25%425%45%9%42%
1612
June1st to 15thNight
12%425%5%2435%7%46%
1440
16th to endNight
8%4245%345%6%10%43%
1440
July1st to 15thNight
7%32342435%8%53%
1440
16th to endNight
7%22442446%10%51%
1549
August1st to 15thNight
6%325%4345%6%9%49%
1620
16th to endNight
10%415%5%23348%50%
1782
September1st to 15thNight
11%413433347%52%
1863
16th to endNight
11%5%24434448%46%
1815
October1st to 15thNight
16%6%26%423346%41%
1871
16th to endNight
21%8%36%5%24446%31%
2244
November1st to 15thNight
15%8%35%424445%38%
2276
16th to endNight
19%13%47%5%35%445%27%
2340
December1st to 15thNight
19%15%7%9%6%3434421%
2424
16th to endNight
21%16%7%10%7%3444414%
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%16%7%9%9%45%6%4415%
1432
16th to endDay
14%19%8%9%9%5%5%445%14%
1575
February1st to 15thDay
13%14%7%11%9%5%6%33420%
1633
16th to endDay
14%13%6%11%7%35%5%46%21%
1580
March1st to 15thDay
15%9%48%6%35%5%5%7%28%
1854
16th to endDay
17%10%5%7%5%24347%30%
2117
April1st to 15thDay
20%11%46%6%24445%30%
2157
16th to endDay
16%7%27%425%45%6%37%
2340
May1st to 15thDay
18%8%37%5%25%45%6%33%
2331
16th to endDay
13%6%26%6%3445%7%39%
2498
June1st to 15thDay
10%435%6%35%5%5%7%41%
2520
16th to endDay
9%426%6%46%6%7%9%37%
2520
July1st to 15thDay
7%4245%25%5%7%9%45%
2520
16th to endDay
7%425%5%26%6%7%8%41%
2618
August1st to 15thDay
9%425%6%36%5%6%9%40%
2340
16th to endDay
10%6%26%5%35%5%6%8%40%
2417
September1st to 15thDay
12%5%245%345%6%8%41%
2005
16th to endDay
11%5%36%5%245%6%9%38%
1815
October1st to 15thDay
14%7%35%6%35%45%7%37%
1758
16th to endDay
21%9%46%5%34435%30%
1625
November1st to 15thDay
13%10%36%5%34446%38%
1582
16th to endDay
17%15%5%7%6%24446%25%
1620
December1st to 15thDay
14%15%8%13%6%35%345%18%
1533
16th to endDay
19%19%8%10%5%3434416%
1536
January1st to 15thNight
21%13%6%9%8%35%43419%
2506
16th to endNight
13%13%9%11%9%45%446%17%
2648
February1st to 15thNight
15%14%5%9%7%45%44424%
2217
16th to endNight
15%10%5%8%8%45%5%46%25%
1893
March1st to 15thNight
15%10%47%5%23446%33%
2106
16th to endNight
14%8%36%435%45%7%35%
2112
April1st to 15thNight
18%9%35%5%235%6%6%33%
1794
16th to endNight
16%7%25%425%447%39%
1620
May1st to 15thNight
18%7%245%3445%8%34%
1619
16th to endNight
12%5%25%425%448%42%
1612
June1st to 15thNight
12%315%5%25%35%7%46%
1440
16th to endNight
8%4245%335%6%10%42%
1440
July1st to 15thNight
6%41342445%8%53%
1440
16th to endNight
6%32442446%10%51%
1549
August1st to 15thNight
5%415%5%3446%9%48%
1620
16th to endNight
10%425%5%23347%50%
1782
September1st to 15thNight
11%41333335%6%52%
1863
16th to endNight
11%425%42445%8%46%
1815
October1st to 15thNight
16%7%25%43335%6%41%
1871
16th to endNight
20%8%37%5%25%445%31%
2244
November1st to 15thNight
14%9%36%434445%38%
2276
16th to endNight
18%12%47%5%35%45%5%26%
2340
December1st to 15thNight
19%15%7%9%6%3434421%
2424
16th to endNight
21%15%8%10%6%35%445%14%
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
70%7%9%10%2
1433
16th to endDay
72%49%9%3
1575
February1st to 15thDay
67%5%7%14%5%
1635
16th to endDay
63%6%10%13%5%
1580
March1st to 15thDay
54%6%12%17%8%
1854
16th to endDay
53%411%20%8%1
2118
April1st to 15thDay
55%49%18%11%
2157
16th to endDay
45%6%13%16%14%3
2340
May1st to 15thDay
50%6%10%20%9%1
2331
16th to endDay
42%6%11%26%11%1
2502
June1st to 15thDay
39%7%12%24%15%
2520
16th to endDay
40%8%13%21%16%
2520
July1st to 15thDay
32%7%11%24%20%2
2371
16th to endDay
36%7%14%24%15%2
2454
August1st to 15thDay
38%7%12%25%12%2
2327
16th to endDay
39%7%11%24%14%2
2417
September1st to 15thDay
37%7%11%25%15%1
2005
16th to endDay
40%5%12%27%13%
1815
October1st to 15thDay
45%5%11%22%13%1
1758
16th to endDay
55%5%13%17%6%
1625
November1st to 15thDay
47%5%11%22%12%1
1582
16th to endDay
60%412%17%5%
1620
December1st to 15thDay
66%6%10%13%2
1533
16th to endDay
71%5%10%9%2
1536
January1st to 15thNight
67%410%11%5%
2506
16th to endNight
67%6%11%11%3
2648
February1st to 15thNight
62%5%9%15%6%
2226
16th to endNight
57%5%12%16%6%1
1893
March1st to 15thNight
51%5%11%19%9%1
2106
16th to endNight
47%5%11%22%10%1
2112
April1st to 15thNight
49%6%10%18%15%
1794
16th to endNight
43%5%12%17%17%3
1620
May1st to 15thNight
47%5%10%21%10%3
1620
16th to endNight
38%6%11%24%15%2
1614
June1st to 15thNight
35%6%12%27%16%1
1440
16th to endNight
33%7%15%25%16%1
1440
July1st to 15thNight
28%5%10%31%20%3
1360
16th to endNight
27%6%15%25%22%2
1450
August1st to 15thNight
29%7%13%29%17%1
1609
16th to endNight
34%5%10%27%18%3
1782
September1st to 15thNight
31%5%10%29%21%1
1863
16th to endNight
35%413%27%18%
1815
October1st to 15thNight
43%410%24%16%1
1871
16th to endNight
53%5%11%21%7%
2244
November1st to 15thNight
46%5%11%21%12%1
2276
16th to endNight
57%5%11%18%5%
2340
December1st to 15thNight
66%5%11%11%5%
2424
16th to endNight
72%5%9%9%3
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
14%13%48%17%5%
90
16th to endDay
30%8%40%16%22
96
February1st to 15thDay
22%20%50%6%1
90
16th to endDay
19%18%34%19%7%
81
March1st to 15thDay
30%8%32%20%7%
144
16th to endDay
25%6%29%23%11%2
288
April1st to 15thDay
24%8%28%26%8%2
270
16th to endDay
20%8%32%18%14%5%
270
May1st to 15thDay
25%8%26%21%12%4
288
16th to endDay
16%7%27%25%14%7%
398
June1st to 15thDay
13%430%29%15%6%
495
16th to endDay
12%6%30%28%16%5%
495
July1st to 15thDay
9%421%30%23%11%
475
16th to endDay
10%225%29%22%10%
478
August1st to 15thDay
9%118%26%20%23%
313
16th to endDay
15%317%18%27%16%
332
September1st to 15thDay
14%219%23%25%16%
299
16th to endDay
17%414%21%29%12%
254
October1st to 15thDay
20%5%20%31%16%5%
255
16th to endDay
26%9%34%23%6%
137
November1st to 15thDay
8%13%24%35%15%2
90
16th to endDay
30%14%34%12%8%
90
December1st to 15thDay
23%23%31%18%21
90
16th to endDay
25%29%38%6%1
96
January1st to 15thNight
26%12%36%18%5%1
900
16th to endNight
18%10%35%30%5%
920
February1st to 15thNight
22%13%36%24%3
704
16th to endNight
21%11%33%27%5%
631
March1st to 15thNight
21%10%32%28%6%
720
16th to endNight
18%9%32%29%9%1
768
April1st to 15thNight
22%9%34%25%6%
543
16th to endNight
21%6%34%27%8%1
540
May1st to 15thNight
23%330%31%8%1
540
16th to endNight
14%228%35%17%1
563
June1st to 15thNight
12%225%43%15%
540
16th to endNight
9%125%40%20%1
540
July1st to 15thNight
9%117%42%27%2
510
16th to endNight
7%117%44%26%2
564
August1st to 15thNight
7%14%47%25%3
539
16th to endNight
11%17%35%28%5%
573
September1st to 15thNight
14%217%34%25%5%
626
16th to endNight
14%417%31%26%5%
657
October1st to 15thNight
19%423%33%16%2
660
16th to endNight
24%10%32%25%7%
704
November1st to 15thNight
19%9%29%29%11%1
700
16th to endNight
25%11%30%24%7%
720
December1st to 15thNight
28%10%35%21%4
804
16th to endNight
30%9%36%20%3
960
Page generated at 2017-09-13 07:39:18. Version ac04

Copyright 2017 A. Danko


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