Kalamazoo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kalamazoo clear sky chart from 2005-11-05 to 2017-08-12.

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
33%
15827
14%
46444
9%
15785
38%
15785
18%
33388

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
7%
2506
3%
895
18%
895
9%
2108
January16th to endNight
14%
957
4%
2685
2%
957
17%
957
7%
2335
February1st to 15thNight
16%
701
8%
2181
2%
701
21%
701
10%
1748
February16th to endNight
22%
631
11%
1893
6%
631
28%
631
12%
1465
March1st to 15thNight
26%
720
14%
2134
8%
720
31%
720
17%
1551
March16th to endNight
29%
732
16%
2076
9%
732
37%
732
19%
1482
April1st to 15thNight
27%
539
13%
1797
8%
539
35%
539
17%
1259
April16th to endNight
31%
540
19%
1648
9%
540
41%
540
22%
1094
May1st to 15thNight
32%
540
13%
1620
6%
540
39%
540
20%
1136
May16th to endNight
43%
562
15%
1578
9%
561
48%
561
28%
1025
June1st to 15thNight
48%
540
16%
1440
9%
540
53%
540
36%
903
June16th to endNight
54%
540
15%
1440
9%
540
59%
540
32%
925
July1st to 15thNight
61%
510
16%
1360
12%
510
64%
510
39%
810
July16th to endNight
67%
564
21%
1420
16%
531
69%
531
39%
841
August1st to 15thNight
65%
527
21%
1575
16%
524
69%
524
36%
893
August16th to endNight
64%
525
19%
1682
16%
525
67%
525
31%
985
September1st to 15thNight
62%
561
26%
1716
24%
561
66%
561
34%
1007
September16th to endNight
54%
657
23%
1815
17%
657
57%
657
31%
1142
October1st to 15thNight
44%
660
23%
1840
18%
660
50%
660
28%
1214
October16th to endNight
23%
704
14%
2277
8%
704
32%
704
15%
1642
November1st to 15thNight
29%
700
18%
2276
14%
700
36%
700
19%
1537
November16th to endNight
22%
720
12%
2340
7%
720
27%
720
11%
1826
December1st to 15thNight
12%
837
5%
2457
2%
837
15%
837
7%
2091
December16th to endNight
11%
960
5%
2688
1%
960
15%
960
6%
2369

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%9%47%6%35%45%7%32%
47531
Night
15%9%47%5%34346%33%
46614
Cloud CoverDay
14%9%47%6%3445%7%32%
47540
Night
15%10%47%5%34446%33%
46619
TransparencyDay
50%6%11%19%10%1
47219
Night
51%5%11%18%10%1
46444
SeeingDay
16%11%28%24%13%5%
5798
Night
19%10%29%27%11%1
15831

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%17%7%10%9%35%5%4413%
1432
16th to endDay
13%19%10%12%10%35%43411%
1539
February1st to 15thDay
12%14%8%15%10%46%34315%
1678
16th to endDay
15%13%8%13%8%45%34418%
1580
March1st to 15thDay
14%12%5%9%6%35%5%5%7%24%
1815
16th to endDay
17%9%47%5%3345%6%31%
2159
April1st to 15thDay
20%12%46%423336%31%
2151
16th to endDay
17%8%2442435%6%38%
2310
May1st to 15thDay
19%8%26%5%4445%6%31%
2331
16th to endDay
12%6%25%5%35%5%5%7%40%
2535
June1st to 15thDay
10%436%5%35%45%8%41%
2520
16th to endDay
9%5%245%36%6%7%10%38%
2520
July1st to 15thDay
6%4245%35%46%10%45%
2520
16th to endDay
7%424435%7%7%10%42%
2651
August1st to 15thDay
7%435%5%35%5%6%9%42%
2288
16th to endDay
12%425%6%25%46%7%40%
2165
September1st to 15thDay
12%5%25%43445%6%43%
1903
16th to endDay
11%6%25%5%345%5%9%40%
1815
October1st to 15thDay
15%8%36%6%34446%37%
1789
16th to endDay
23%10%36%5%25%446%27%
1592
November1st to 15thDay
14%10%46%425%446%36%
1582
16th to endDay
18%17%6%10%6%24335%19%
1620
December1st to 15thDay
17%19%12%10%5%3333316%
1500
16th to endDay
21%20%9%10%6%3334411%
1536
January1st to 15thNight
19%16%7%12%6%3434417%
2506
16th to endNight
14%13%10%13%11%45%445%12%
2685
February1st to 15thNight
14%16%7%11%7%44345%21%
2179
16th to endNight
16%9%7%9%7%45%45%5%24%
1893
March1st to 15thNight
17%10%47%5%24346%33%
2121
16th to endNight
15%8%46%6%3435%6%33%
2076
April1st to 15thNight
18%8%45%5%3445%7%32%
1797
16th to endNight
17%7%25%42445%6%40%
1648
May1st to 15thNight
19%7%26%5%24348%33%
1620
16th to endNight
12%6%25%42446%9%42%
1576
June1st to 15thNight
10%415%42335%9%47%
1440
16th to endNight
8%325%425%5%6%10%43%
1440
July1st to 15thNight
6%21443447%7%53%
1440
16th to endNight
6%32432446%8%51%
1516
August1st to 15thNight
5%3145%346%5%9%50%
1586
16th to endNight
9%42442445%5%50%
1682
September1st to 15thNight
11%42332435%7%50%
1716
16th to endNight
11%7%25%325%446%47%
1815
October1st to 15thNight
15%7%245%23346%43%
1840
16th to endNight
23%8%35%5%34336%32%
2277
November1st to 15thNight
15%10%46%5%23345%37%
2276
16th to endNight
20%14%6%8%5%24345%22%
2340
December1st to 15thNight
21%20%8%10%5%3333415%
2457
16th to endNight
22%17%8%10%6%35%44311%
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%7%10%9%445%4413%
1432
16th to endDay
13%19%9%12%11%4434312%
1539
February1st to 15thDay
12%14%8%15%10%45%24415%
1678
16th to endDay
15%14%7%13%7%45%34418%
1580
March1st to 15thDay
14%12%5%9%6%45%45%7%25%
1825
16th to endDay
17%9%47%5%3435%6%32%
2158
April1st to 15thDay
20%12%46%433346%31%
2151
16th to endDay
17%8%24425%447%38%
2310
May1st to 15thDay
19%8%35%6%35%5%5%6%31%
2331
16th to endDay
12%5%345%345%5%8%41%
2535
June1st to 15thDay
10%426%5%345%5%8%41%
2520
16th to endDay
9%5%345%36%6%7%9%38%
2520
July1st to 15thDay
6%425%5%35%46%10%45%
2520
16th to endDay
8%325%435%6%6%10%42%
2651
August1st to 15thDay
8%425%5%35%5%6%9%42%
2288
16th to endDay
12%435%5%35%5%5%7%40%
2165
September1st to 15thDay
13%5%25%5%345%46%43%
1903
16th to endDay
11%6%36%43446%8%40%
1815
October1st to 15thDay
15%7%26%5%35%446%38%
1789
16th to endDay
23%10%26%5%35%446%27%
1592
November1st to 15thDay
14%10%35%5%34446%36%
1582
16th to endDay
18%18%5%9%6%34345%20%
1620
December1st to 15thDay
17%19%12%10%6%3423316%
1500
16th to endDay
21%20%9%10%6%4333411%
1536
January1st to 15thNight
19%16%7%12%7%35%33417%
2506
16th to endNight
14%13%10%13%10%45%445%12%
2685
February1st to 15thNight
14%16%7%11%8%43345%21%
2172
16th to endNight
16%10%6%9%8%45%445%24%
1893
March1st to 15thNight
17%10%47%5%24345%33%
2134
16th to endNight
15%7%46%5%34348%33%
2076
April1st to 15thNight
18%8%45%6%34447%32%
1797
16th to endNight
17%7%25%5%23446%39%
1648
May1st to 15thNight
20%7%26%5%33448%33%
1619
16th to endNight
12%6%15%42435%9%42%
1576
June1st to 15thNight
11%415%42335%9%47%
1440
16th to endNight
7%424435%6%6%10%43%
1440
July1st to 15thNight
6%32433445%9%52%
1440
16th to endNight
5%313325%46%9%52%
1516
August1st to 15thNight
5%3145%35%5%5%9%50%
1586
16th to endNight
9%415%435%35%5%50%
1682
September1st to 15thNight
12%424323447%50%
1716
16th to endNight
11%7%25%425%346%46%
1815
October1st to 15thNight
15%7%245%23346%43%
1840
16th to endNight
23%8%26%5%34335%33%
2277
November1st to 15thNight
15%11%36%5%23435%37%
2276
16th to endNight
20%15%5%8%6%24445%23%
2340
December1st to 15thNight
21%19%8%10%5%3333315%
2457
16th to endNight
22%17%8%10%6%345%3411%
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
72%6%11%6%2
1433
16th to endDay
76%5%8%6%2
1539
February1st to 15thDay
72%5%6%11%3
1680
16th to endDay
69%5%10%10%4
1580
March1st to 15thDay
58%6%12%16%6%
1825
16th to endDay
53%5%11%22%6%1
2159
April1st to 15thDay
54%5%9%18%12%
2151
16th to endDay
45%5%13%17%13%3
2310
May1st to 15thDay
50%6%13%20%8%
2331
16th to endDay
40%7%13%24%12%1
2539
June1st to 15thDay
38%7%11%24%17%
2520
16th to endDay
38%9%15%19%16%1
2520
July1st to 15thDay
34%6%11%23%20%3
2371
16th to endDay
31%10%15%23%16%2
2484
August1st to 15thDay
35%8%13%25%14%2
2275
16th to endDay
39%6%12%24%14%2
2165
September1st to 15thDay
39%5%12%24%15%2
1903
16th to endDay
39%6%11%26%14%
1815
October1st to 15thDay
46%411%23%13%
1789
16th to endDay
56%5%13%17%6%
1592
November1st to 15thDay
48%5%11%21%11%1
1582
16th to endDay
66%411%14%2
1620
December1st to 15thDay
73%48%10%2
1500
16th to endDay
76%5%9%6%1
1536
January1st to 15thNight
70%5%9%10%3
2506
16th to endNight
73%5%11%6%1
2685
February1st to 15thNight
65%5%10%13%4
2181
16th to endNight
61%5%12%15%41
1893
March1st to 15thNight
52%5%12%17%9%1
2134
16th to endNight
50%5%12%21%8%1
2076
April1st to 15thNight
50%5%10%18%13%
1797
16th to endNight
44%5%10%18%16%3
1648
May1st to 15thNight
49%5%12%21%9%2
1620
16th to endNight
38%8%13%23%14%2
1578
June1st to 15thNight
33%5%12%28%18%1
1440
16th to endNight
32%10%16%22%16%1
1440
July1st to 15thNight
27%8%14%26%20%2
1360
16th to endNight
27%8%14%24%21%3
1420
August1st to 15thNight
28%7%14%27%20%1
1575
16th to endNight
34%5%11%25%18%5%
1682
September1st to 15thNight
32%5%11%28%20%2
1716
16th to endNight
37%410%27%18%1
1815
October1st to 15thNight
41%5%9%25%18%
1840
16th to endNight
54%5%10%19%9%
2277
November1st to 15thNight
49%410%20%12%2
2276
16th to endNight
62%5%11%16%2
2340
December1st to 15thNight
73%48%9%3
2457
16th to endNight
75%5%9%7%1
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
20%21%43%13%2
90
16th to endDay
29%14%39%11%5%
96
February1st to 15thDay
18%33%35%11%1
90
16th to endDay
18%20%35%19%31
81
March1st to 15thDay
29%18%31%14%6%
115
16th to endDay
26%14%31%18%7%1
288
April1st to 15thDay
28%11%31%20%7%
270
16th to endDay
21%15%30%16%11%4
270
May1st to 15thDay
23%15%26%21%8%4
288
16th to endDay
16%11%31%24%11%5%
435
June1st to 15thDay
12%8%35%27%11%4
495
16th to endDay
12%11%31%26%13%3
495
July1st to 15thDay
9%6%27%30%17%9%
475
16th to endDay
8%326%31%20%8%
511
August1st to 15thDay
9%220%24%24%18%
297
16th to endDay
18%418%24%22%12%
268
September1st to 15thDay
12%417%29%23%12%
255
16th to endDay
13%7%18%27%25%7%
254
October1st to 15thDay
18%10%21%29%16%3
255
16th to endDay
24%16%40%17%1
104
November1st to 15thDay
10%16%23%38%8%2
90
16th to endDay
32%27%28%7%3
90
December1st to 15thDay
28%30%24%14%2
90
16th to endDay
23%37%35%21
96
January1st to 15thNight
27%15%33%19%3
900
16th to endNight
19%12%38%26%3
957
February1st to 15thNight
21%16%36%20%4
704
16th to endNight
19%17%32%24%4
631
March1st to 15thNight
22%12%32%24%7%
720
16th to endNight
17%13%34%27%7%
732
April1st to 15thNight
21%13%33%25%5%
539
16th to endNight
21%9%36%25%6%1
540
May1st to 15thNight
22%7%31%28%8%
540
16th to endNight
17%430%33%13%
563
June1st to 15thNight
12%429%38%14%
540
16th to endNight
9%226%40%18%1
540
July1st to 15thNight
8%221%41%23%2
510
16th to endNight
6%316%42%28%2
564
August1st to 15thNight
8%16%44%26%3
527
16th to endNight
10%215%37%29%4
525
September1st to 15thNight
13%316%36%24%4
561
16th to endNight
14%7%18%30%25%3
657
October1st to 15thNight
19%6%24%30%17%1
660
16th to endNight
26%13%32%19%7%
704
November1st to 15thNight
22%13%29%24%10%
700
16th to endNight
28%15%28%22%5%
720
December1st to 15thNight
30%15%34%16%2
837
16th to endNight
31%15%35%15%2
960
Page generated at 2017-08-13 14:16:19. Version ac04

Copyright 2017 A. Danko


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