Cedar Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cedar Springs clear sky chart from 2005-11-05 to 2017-09-21.

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
36%
16014
14%
46863
9%
15973
41%
15973
20%
33377

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%
900
6%
2506
3%
895
20%
895
9%
2119
January16th to endNight
21%
960
6%
2688
3%
960
23%
960
9%
2261
February1st to 15thNight
20%
721
9%
2219
4%
721
25%
721
10%
1769
February16th to endNight
25%
631
10%
1893
5%
631
30%
631
12%
1462
March1st to 15thNight
31%
720
15%
2136
10%
720
35%
720
19%
1497
March16th to endNight
32%
729
18%
2073
11%
729
39%
729
23%
1434
April1st to 15thNight
31%
539
13%
1797
9%
539
37%
539
18%
1251
April16th to endNight
34%
540
20%
1638
10%
540
44%
540
24%
1060
May1st to 15thNight
35%
540
15%
1620
9%
540
41%
540
21%
1112
May16th to endNight
44%
561
15%
1548
9%
561
49%
561
28%
1028
June1st to 15thNight
49%
540
14%
1440
9%
540
53%
540
33%
928
June16th to endNight
54%
540
14%
1440
8%
540
58%
540
32%
926
July1st to 15thNight
65%
510
16%
1360
12%
510
66%
510
42%
790
July16th to endNight
64%
564
19%
1417
15%
531
66%
531
39%
853
August1st to 15thNight
65%
539
21%
1590
16%
536
69%
536
38%
910
August16th to endNight
63%
573
21%
1818
20%
573
67%
573
32%
1079
September1st to 15thNight
62%
609
24%
1869
22%
609
66%
609
36%
1072
September16th to endNight
56%
681
22%
1881
17%
681
58%
681
34%
1152
October1st to 15thNight
46%
660
21%
1848
16%
660
50%
660
28%
1211
October16th to endNight
29%
704
13%
2285
7%
704
36%
704
16%
1621
November1st to 15thNight
32%
700
18%
2276
14%
700
38%
700
19%
1558
November16th to endNight
26%
720
10%
2340
7%
720
31%
720
12%
1816
December1st to 15thNight
17%
873
4%
2493
2%
873
20%
873
7%
2157
December16th to endNight
14%
960
6%
2688
1%
960
18%
960
8%
2311

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%33%
48008
Night
14%9%47%5%3445%6%33%
47031
Cloud CoverDay
14%8%46%6%35%45%7%33%
48017
Night
14%9%47%5%3445%6%34%
47036
TransparencyDay
49%6%12%19%10%1
47694
Night
50%6%12%19%10%1
46863
SeeingDay
16%8%27%25%14%6%
6003
Night
18%8%28%30%12%1
16019

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%14%7%11%8%6%5%5%45%12%
1432
16th to endDay
13%17%10%13%11%5%5%43311%
1536
February1st to 15thDay
11%17%7%10%12%5%5%33417%
1639
16th to endDay
13%12%7%12%8%35%46%5%19%
1580
March1st to 15thDay
16%9%47%6%35%5%5%7%28%
1814
16th to endDay
16%8%37%5%3445%5%34%
2162
April1st to 15thDay
19%12%45%5%2335%6%30%
2151
16th to endDay
17%8%25%5%35%45%6%36%
2322
May1st to 15thDay
20%7%35%42435%7%35%
2331
16th to endDay
10%5%26%5%35%45%8%41%
2565
June1st to 15thDay
12%5%25%5%345%6%7%40%
2520
16th to endDay
10%5%25%5%36%46%9%40%
2520
July1st to 15thDay
6%415%435%5%6%9%47%
2520
16th to endDay
8%4245%35%5%6%10%43%
2655
August1st to 15thDay
8%5%25%6%45%5%7%8%38%
2359
16th to endDay
11%5%25%43436%8%43%
2381
September1st to 15thDay
12%425%43436%8%43%
2079
16th to endDay
11%5%25%5%345%5%9%40%
1872
October1st to 15thDay
16%8%37%5%34335%38%
1782
16th to endDay
20%10%38%7%35%35%5%26%
1584
November1st to 15thDay
14%10%36%5%24446%36%
1582
16th to endDay
21%15%5%7%5%3445%5%20%
1620
December1st to 15thDay
15%18%8%12%8%345%3415%
1466
16th to endDay
20%17%10%12%6%3444412%
1536
January1st to 15thNight
19%13%8%11%7%4444417%
2506
16th to endNight
11%14%9%12%7%45%5%5%6%16%
2688
February1st to 15thNight
11%16%7%9%8%36%44422%
2217
16th to endNight
15%12%49%8%446%5%6%22%
1893
March1st to 15thNight
15%10%36%5%3435%7%35%
2123
16th to endNight
14%8%47%5%24446%36%
2073
April1st to 15thNight
20%8%35%5%34446%33%
1797
16th to endNight
16%8%35%313346%41%
1638
May1st to 15thNight
15%5%347%345%5%7%35%
1620
16th to endNight
11%7%26%5%2445%8%41%
1546
June1st to 15thNight
9%6%26%335%46%8%44%
1440
16th to endNight
8%325%5%35%5%6%9%44%
1440
July1st to 15thNight
6%3233245%6%7%54%
1440
16th to endNight
6%3144335%7%7%52%
1513
August1st to 15thNight
6%324425%5%5%8%51%
1599
16th to endNight
10%41343345%7%50%
1818
September1st to 15thNight
10%314424447%53%
1869
16th to endNight
9%5%25%324436%50%
1881
October1st to 15thNight
16%6%35%423447%42%
1848
16th to endNight
20%8%36%433447%33%
2285
November1st to 15thNight
14%9%37%5%3446%7%35%
2276
16th to endNight
19%13%38%6%35%45%7%21%
2340
December1st to 15thNight
19%16%7%10%8%35%445%14%
2493
16th to endNight
21%16%7%8%7%35%345%14%
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%14%6%11%9%6%6%5%45%13%
1432
16th to endDay
13%18%10%12%11%5%6%43311%
1536
February1st to 15thDay
11%16%7%10%12%46%33418%
1639
16th to endDay
13%12%8%11%7%46%36%5%20%
1580
March1st to 15thDay
16%9%46%6%45%45%6%28%
1824
16th to endDay
16%8%46%6%3435%5%35%
2161
April1st to 15thDay
19%11%45%5%2435%6%30%
2151
16th to endDay
17%8%25%5%35%45%6%36%
2322
May1st to 15thDay
21%6%35%43335%7%35%
2331
16th to endDay
11%5%25%6%35%5%5%8%41%
2565
June1st to 15thDay
12%5%35%5%35%45%8%40%
2520
16th to endDay
10%5%25%5%46%45%9%40%
2520
July1st to 15thDay
7%324435%5%7%8%47%
2520
16th to endDay
9%3245%35%5%5%9%44%
2655
August1st to 15thDay
9%5%35%6%45%5%7%8%38%
2359
16th to endDay
11%5%25%43345%8%43%
2381
September1st to 15thDay
12%425%44436%8%43%
2079
16th to endDay
11%5%25%4445%6%7%40%
1872
October1st to 15thDay
17%7%46%5%24336%38%
1782
16th to endDay
20%9%48%6%35%445%27%
1584
November1st to 15thDay
14%10%36%5%2445%6%36%
1582
16th to endDay
21%15%5%8%6%3445%5%21%
1620
December1st to 15thDay
14%18%8%12%7%35%44415%
1466
16th to endDay
19%17%10%11%6%25%44413%
1536
January1st to 15thNight
20%13%8%11%7%3444417%
2506
16th to endNight
12%13%9%12%8%35%6%5%7%16%
2688
February1st to 15thNight
12%15%7%9%8%45%44422%
2210
16th to endNight
15%12%5%8%7%445%6%6%22%
1893
March1st to 15thNight
15%9%36%5%24447%35%
2136
16th to endNight
14%9%46%5%34446%36%
2073
April1st to 15thNight
20%8%35%5%34446%34%
1797
16th to endNight
16%8%25%313446%41%
1638
May1st to 15thNight
15%6%35%6%4446%7%35%
1619
16th to endNight
11%6%35%5%2435%8%41%
1546
June1st to 15thNight
9%5%26%335%46%8%44%
1440
16th to endNight
7%435%435%5%5%9%44%
1440
July1st to 15thNight
6%3133245%5%7%54%
1440
16th to endNight
6%21442447%8%52%
1513
August1st to 15thNight
6%3244245%6%8%51%
1599
16th to endNight
10%42442435%7%50%
1818
September1st to 15thNight
10%31332445%6%53%
1869
16th to endNight
10%5%26%324436%50%
1881
October1st to 15thNight
16%6%35%423447%42%
1848
16th to endNight
20%9%36%434336%33%
2285
November1st to 15thNight
14%8%46%6%3446%6%35%
2276
16th to endNight
19%13%5%6%6%35%45%6%22%
2340
December1st to 15thNight
19%15%8%10%7%36%44415%
2493
16th to endNight
21%16%7%9%6%34445%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
73%8%8%8%1
1433
16th to endDay
78%6%6%6%2
1536
February1st to 15thDay
71%5%6%13%2
1641
16th to endDay
64%6%11%12%5%
1580
March1st to 15thDay
53%6%13%17%7%
1824
16th to endDay
50%6%12%22%6%1
2162
April1st to 15thDay
53%5%9%19%11%
2151
16th to endDay
46%5%13%17%13%2
2322
May1st to 15thDay
47%5%13%21%10%1
2331
16th to endDay
39%7%13%25%12%
2569
June1st to 15thDay
40%7%12%23%15%
2520
16th to endDay
37%8%14%21%17%1
2520
July1st to 15thDay
32%6%14%25%18%2
2371
16th to endDay
35%7%14%24%16%2
2488
August1st to 15thDay
39%6%13%26%12%1
2344
16th to endDay
37%6%13%24%15%2
2381
September1st to 15thDay
37%5%12%27%13%2
2079
16th to endDay
40%5%14%25%14%
1872
October1st to 15thDay
48%5%10%22%12%1
1782
16th to endDay
59%414%16%4
1584
November1st to 15thDay
47%7%12%21%10%
1582
16th to endDay
64%5%13%12%3
1620
December1st to 15thDay
72%5%9%8%2
1466
16th to endDay
74%6%10%6%1
1536
January1st to 15thNight
69%5%9%10%3
2506
16th to endNight
66%8%13%8%2
2688
February1st to 15thNight
65%49%14%4
2219
16th to endNight
60%5%13%14%5%
1893
March1st to 15thNight
48%6%13%20%10%1
2136
16th to endNight
47%412%23%9%2
2073
April1st to 15thNight
51%410%17%14%
1797
16th to endNight
43%411%20%15%4
1638
May1st to 15thNight
46%6%11%20%11%2
1620
16th to endNight
41%6%11%23%15%1
1548
June1st to 15thNight
35%6%11%27%16%1
1440
16th to endNight
35%8%15%23%16%1
1440
July1st to 15thNight
26%7%13%29%21%2
1360
16th to endNight
28%8%15%27%18%2
1417
August1st to 15thNight
28%6%13%31%17%1
1590
16th to endNight
33%6%10%27%19%2
1818
September1st to 15thNight
29%6%12%30%18%1
1869
16th to endNight
34%5%13%32%13%
1881
October1st to 15thNight
41%5%11%25%15%1
1848
16th to endNight
52%5%14%19%8%
2285
November1st to 15thNight
47%7%12%20%11%1
2276
16th to endNight
61%6%12%15%2
2340
December1st to 15thNight
72%7%9%7%3
2493
16th to endNight
72%6%11%8%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%36%21%2
90
16th to endDay
33%239%18%5%1
96
February1st to 15thDay
27%22%41%8%
90
16th to endDay
23%17%28%27%21
81
March1st to 15thDay
33%12%26%20%7%
114
16th to endDay
25%10%25%27%8%3
288
April1st to 15thDay
28%8%29%23%7%1
270
16th to endDay
21%10%29%21%10%6%
270
May1st to 15thDay
24%11%25%22%9%5%
288
16th to endDay
13%11%29%25%15%5%
465
June1st to 15thDay
12%7%34%28%12%4
495
16th to endDay
12%8%32%28%11%5%
495
July1st to 15thDay
8%6%25%31%17%10%
475
16th to endDay
8%427%30%19%9%
515
August1st to 15thDay
11%219%26%22%17%
332
16th to endDay
16%417%25%21%13%
332
September1st to 15thDay
11%216%31%26%12%
315
16th to endDay
13%416%29%27%9%
275
October1st to 15thDay
20%8%21%29%16%3
255
16th to endDay
23%13%41%20%
96
November1st to 15thDay
12%14%38%18%11%4
90
16th to endDay
34%14%32%12%6%
90
December1st to 15thDay
24%26%36%8%21
90
16th to endDay
28%33%31%6%1
96
January1st to 15thNight
25%13%32%20%7%
900
16th to endNight
19%9%34%31%4
960
February1st to 15thNight
19%12%35%28%4
724
16th to endNight
22%12%30%29%5%
631
March1st to 15thNight
20%9%32%28%8%
720
16th to endNight
17%9%32%30%8%1
729
April1st to 15thNight
22%11%31%28%5%1
539
16th to endNight
21%10%31%28%6%1
540
May1st to 15thNight
19%5%32%32%9%
540
16th to endNight
14%5%28%34%15%1
563
June1st to 15thNight
10%5%28%38%16%
540
16th to endNight
10%227%40%18%1
540
July1st to 15thNight
7%119%46%22%2
510
16th to endNight
7%121%41%26%1
564
August1st to 15thNight
8%118%45%24%2
539
16th to endNight
12%214%37%29%3
573
September1st to 15thNight
10%318%39%22%5%
609
16th to endNight
13%5%19%32%24%4
681
October1st to 15thNight
19%5%24%33%15%1
660
16th to endNight
25%10%30%22%9%
704
November1st to 15thNight
20%9%32%26%10%1
700
16th to endNight
25%12%30%25%5%
720
December1st to 15thNight
27%10%34%22%4
873
16th to endNight
28%10%36%20%3
960
Page generated at 2017-09-22 07:35:33. Version ac04

Copyright 2017 A. Danko


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