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 2018-01-12.

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%
16442
15%
48288
10%
16400
42%
16400
20%
34034

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
17%
956
8%
2662
3%
951
22%
951
11%
2169
January16th to endNight
21%
920
7%
2648
3%
920
25%
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
27%
543
13%
1794
9%
543
34%
543
18%
1237
April16th to endNight
36%
540
19%
1620
9%
540
45%
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
53%
540
15%
1440
11%
540
56%
540
32%
916
June16th to endNight
55%
540
15%
1440
11%
540
59%
540
33%
909
July1st to 15thNight
66%
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
17%
536
70%
536
36%
938
August16th to endNight
61%
573
21%
1782
17%
573
65%
573
32%
1051
September1st to 15thNight
60%
639
26%
1899
22%
639
64%
639
35%
1103
September16th to endNight
59%
717
24%
1980
18%
717
62%
717
34%
1207
October1st to 15thNight
44%
720
19%
2041
15%
720
49%
720
26%
1380
October16th to endNight
28%
768
16%
2448
9%
768
38%
768
17%
1753
November1st to 15thNight
35%
760
18%
2471
16%
760
40%
760
20%
1669
November16th to endNight
26%
780
14%
2535
8%
780
33%
780
15%
1867
December1st to 15thNight
17%
871
7%
2626
2%
871
21%
871
10%
2129
December16th to endNight
15%
1040
8%
2912
2%
1040
20%
1040
8%
2494

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%
49048
Night
15%9%46%5%34446%34%
48461
Cloud CoverDay
13%8%47%6%35%45%7%33%
49057
Night
14%9%47%5%34446%34%
48466
TransparencyDay
49%6%11%20%11%1
48739
Night
49%5%11%20%11%1
48288
SeeingDay
17%7%26%24%16%7%
6318
Night
19%7%28%30%12%1
16446

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
16%16%7%9%8%5%6%5%45%15%
1520
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%6%8%42%
2049
16th to endDay
11%5%25%5%35%45%9%41%
1980
October1st to 15thDay
15%6%35%5%34447%38%
1918
16th to endDay
21%9%36%6%34445%30%
1773
November1st to 15thDay
15%10%35%5%24436%37%
1717
16th to endDay
17%15%5%6%5%34446%27%
1755
December1st to 15thDay
15%14%9%11%6%35%345%19%
1661
16th to endDay
19%19%8%9%6%3434415%
1664
January1st to 15thNight
20%13%6%8%8%345%35%20%
2662
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%
1899
16th to endNight
10%5%24433448%47%
1980
October1st to 15thNight
17%7%26%423346%40%
2041
16th to endNight
20%8%36%5%24446%32%
2448
November1st to 15thNight
16%8%36%424445%37%
2471
16th to endNight
18%12%47%5%35%446%28%
2535
December1st to 15thNight
18%15%7%10%6%4434421%
2626
16th to endNight
21%16%7%9%7%4444415%
2912

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%
1520
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%246%345%6%8%41%
2049
16th to endDay
10%5%36%4345%5%9%40%
1980
October1st to 15thDay
15%7%35%6%35%45%7%37%
1918
16th to endDay
20%9%46%5%35%435%30%
1773
November1st to 15thDay
15%10%35%5%24346%37%
1717
16th to endDay
16%14%5%7%6%23446%27%
1755
December1st to 15thDay
14%15%8%12%6%35%445%19%
1661
16th to endDay
19%19%7%10%6%3444415%
1664
January1st to 15thNight
20%13%6%8%8%35%44419%
2662
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
10%41333435%6%52%
1899
16th to endNight
10%425%4245%5%8%47%
1980
October1st to 15thNight
16%7%25%5%33346%40%
2041
16th to endNight
20%8%37%5%24445%32%
2448
November1st to 15thNight
15%9%36%434445%37%
2471
16th to endNight
18%12%47%5%3445%6%27%
2535
December1st to 15thNight
18%15%7%10%6%3434421%
2626
16th to endNight
20%15%8%10%7%35%445%14%
2912

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%6%8%11%2
1521
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
2049
16th to endDay
39%5%12%27%15%
1980
October1st to 15thDay
45%5%11%22%12%1
1918
16th to endDay
55%5%13%17%6%
1773
November1st to 15thDay
48%5%11%21%11%1
1717
16th to endDay
58%413%17%5%
1755
December1st to 15thDay
65%5%10%13%3
1661
16th to endDay
71%5%10%9%3
1664
January1st to 15thNight
66%410%12%5%
2662
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%30%21%1
1899
16th to endNight
34%413%28%18%
1980
October1st to 15thNight
44%410%23%15%1
2041
16th to endNight
52%5%11%21%7%
2448
November1st to 15thNight
47%5%11%21%11%1
2471
16th to endNight
56%5%12%19%6%
2535
December1st to 15thNight
66%5%11%11%5%
2626
16th to endNight
72%5%9%9%3
2912

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
13%10%48%20%6%
123
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
13%118%22%26%17%
315
16th to endDay
15%414%21%28%15%
314
October1st to 15thDay
21%5%21%29%17%5%
315
16th to endDay
25%8%33%23%7%
189
November1st to 15thDay
20%10%24%30%12%1
135
16th to endDay
26%17%35%12%7%
135
December1st to 15thDay
24%22%28%18%5%
135
16th to endDay
26%25%34%11%1
144
January1st to 15thNight
26%11%35%20%5%
956
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
13%217%34%26%5%
639
16th to endNight
13%417%30%27%5%
717
October1st to 15thNight
20%423%32%16%2
720
16th to endNight
23%10%32%25%7%
768
November1st to 15thNight
20%8%28%30%10%
760
16th to endNight
24%11%32%24%6%
780
December1st to 15thNight
27%10%35%21%4
871
16th to endNight
29%9%36%20%2
1040
Page generated at 2018-01-12 22:01:24. Version ac04

Copyright 2018 A. Danko


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