Marion
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marion clear sky chart from 2005-11-05 to 2017-04-26.

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
38%
15400
16%
45541
11%
15358
43%
15358
22%
31276

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
11%
2506
4%
895
22%
895
13%
1982
January16th to endNight
18%
907
11%
2635
4%
907
24%
907
13%
2052
February1st to 15thNight
20%
701
9%
2145
3%
701
25%
701
14%
1583
February16th to endNight
21%
631
14%
1893
5%
631
29%
631
15%
1405
March1st to 15thNight
28%
720
13%
2133
9%
720
32%
720
16%
1549
March16th to endNight
29%
735
15%
2079
8%
735
36%
735
20%
1479
April1st to 15thNight
32%
539
15%
1797
9%
539
41%
539
19%
1214
April16th to endNight
36%
528
21%
1635
11%
528
45%
528
25%
1064
May1st to 15thNight
37%
495
14%
1485
10%
495
41%
495
20%
1066
May16th to endNight
54%
514
15%
1503
12%
513
57%
513
27%
982
June1st to 15thNight
58%
495
18%
1320
13%
495
62%
495
35%
827
June16th to endNight
58%
495
16%
1320
11%
495
61%
495
32%
858
July1st to 15thNight
64%
465
17%
1240
14%
465
66%
465
35%
788
July16th to endNight
72%
522
19%
1348
16%
489
74%
489
41%
793
August1st to 15thNight
69%
494
22%
1474
19%
491
71%
491
36%
856
August16th to endNight
68%
525
19%
1715
18%
525
72%
525
34%
964
September1st to 15thNight
65%
566
27%
1721
24%
566
69%
566
36%
992
September16th to endNight
60%
657
25%
1815
19%
657
64%
657
34%
1107
October1st to 15thNight
51%
660
26%
1826
20%
660
57%
660
34%
1118
October16th to endNight
31%
704
18%
2260
13%
704
39%
704
21%
1485
November1st to 15thNight
37%
700
24%
2276
17%
700
47%
700
26%
1369
November16th to endNight
27%
720
16%
2340
10%
720
35%
720
16%
1659
December1st to 15thNight
20%
767
9%
2387
4%
767
25%
767
12%
1850
December16th to endNight
16%
960
9%
2688
2%
960
22%
960
10%
2234

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%36%5%3445%7%34%
46118
Night
15%8%36%5%24446%37%
45715
Cloud CoverDay
14%8%36%5%35%45%7%34%
46127
Night
15%8%36%5%34446%37%
45720
TransparencyDay
48%6%12%19%11%1
45810
Night
47%5%11%20%13%2
45541
SeeingDay
17%6%24%24%19%8%
5225
Night
19%8%27%28%14%1
15404

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
21%15%5%8%6%43346%20%
1432
16th to endDay
13%17%8%9%6%35%44421%
1587
February1st to 15thDay
15%14%6%11%7%34345%23%
1714
16th to endDay
14%13%6%9%7%35%345%25%
1580
March1st to 15thDay
20%12%5%7%5%24447%24%
1817
16th to endDay
17%10%5%7%5%2335%7%30%
2154
April1st to 15thDay
20%9%35%5%24446%34%
2151
16th to endDay
17%7%25%5%3345%7%35%
2236
May1st to 15thDay
20%8%46%7%35%45%6%27%
2136
16th to endDay
11%5%25%6%45%5%7%7%37%
2258
June1st to 15thDay
12%425%5%45%5%5%7%39%
2310
16th to endDay
10%425%6%36%5%6%10%38%
2310
July1st to 15thDay
10%425%5%245%6%10%41%
2310
16th to endDay
8%4245%36%7%7%9%39%
2410
August1st to 15thDay
6%3245%35%6%6%9%44%
2145
16th to endDay
8%415%5%35%6%6%8%43%
2132
September1st to 15thDay
12%5%24434448%44%
1898
16th to endDay
12%5%24425%447%45%
1815
October1st to 15thDay
13%5%26%5%24445%43%
1804
16th to endDay
19%7%35%5%25%35%6%35%
1610
November1st to 15thDay
12%6%24434345%46%
1582
16th to endDay
20%10%5%7%6%24345%28%
1620
December1st to 15thDay
19%15%5%11%5%3443422%
1571
16th to endDay
22%16%5%9%5%25%44418%
1536
January1st to 15thNight
20%14%5%8%7%3323425%
2506
16th to endNight
16%14%7%9%6%3444425%
2635
February1st to 15thNight
16%13%5%7%6%24345%29%
2143
16th to endNight
14%12%5%8%6%34345%30%
1893
March1st to 15thNight
17%10%47%6%25%345%32%
2120
16th to endNight
15%9%37%5%3445%6%33%
2079
April1st to 15thNight
17%7%25%5%35%45%5%36%
1797
16th to endNight
17%6%245%2345%7%40%
1635
May1st to 15thNight
19%8%36%5%3435%7%32%
1485
16th to endNight
12%5%35%42445%8%41%
1501
June1st to 15thNight
8%436%4235%49%46%
1320
16th to endNight
9%5%25%435%5%5%9%44%
1320
July1st to 15thNight
9%4235%345%5%9%47%
1320
16th to endNight
5%325%4235%6%8%51%
1448
August1st to 15thNight
5%4243345%5%8%50%
1485
16th to endNight
7%3244345%5%8%50%
1715
September1st to 15thNight
10%413424448%52%
1721
16th to endNight
11%4245%2335%6%50%
1815
October1st to 15thNight
12%5%2442335%7%49%
1826
16th to endNight
18%6%35%424345%39%
2260
November1st to 15thNight
13%8%35%41335%6%45%
2276
16th to endNight
19%10%47%5%34347%30%
2340
December1st to 15thNight
21%12%6%8%6%2334425%
2387
16th to endNight
23%15%5%8%6%2433419%
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
21%15%5%9%6%43346%21%
1432
16th to endDay
14%17%7%9%6%35%345%21%
1587
February1st to 15thDay
15%14%7%11%7%25%345%23%
1714
16th to endDay
14%13%6%9%7%34445%25%
1580
March1st to 15thDay
21%12%5%8%424447%24%
1827
16th to endDay
17%10%5%7%5%1436%7%30%
2153
April1st to 15thDay
19%9%35%424447%33%
2151
16th to endDay
17%7%26%5%3345%7%35%
2236
May1st to 15thDay
21%7%46%7%35%45%6%27%
2136
16th to endDay
11%5%26%6%45%5%7%8%37%
2258
June1st to 15thDay
12%425%6%35%5%5%7%39%
2310
16th to endDay
10%325%5%36%5%7%9%38%
2310
July1st to 15thDay
10%5%25%5%245%6%10%41%
2310
16th to endDay
8%4246%26%6%8%10%39%
2410
August1st to 15thDay
6%4245%45%6%6%9%44%
2145
16th to endDay
8%425%5%36%5%6%8%43%
2132
September1st to 15thDay
13%5%2443445%7%44%
1898
16th to endDay
12%5%25%335%35%7%45%
1815
October1st to 15thDay
13%5%36%5%245%46%43%
1804
16th to endDay
19%7%35%5%25%35%6%35%
1610
November1st to 15thDay
12%6%25%433346%45%
1582
16th to endDay
20%10%5%8%6%24345%29%
1620
December1st to 15thDay
19%15%5%11%5%2443422%
1571
16th to endDay
22%16%5%9%5%25%45%418%
1536
January1st to 15thNight
20%14%5%8%7%3323425%
2506
16th to endNight
16%14%7%9%6%3334425%
2635
February1st to 15thNight
16%13%5%7%6%33345%29%
2136
16th to endNight
14%12%5%8%6%35%345%29%
1893
March1st to 15thNight
17%10%46%6%35%345%32%
2133
16th to endNight
15%10%37%5%3445%7%33%
2079
April1st to 15thNight
17%6%245%35%45%5%36%
1797
16th to endNight
17%7%245%2345%7%40%
1635
May1st to 15thNight
19%8%36%5%3435%6%32%
1484
16th to endNight
11%5%25%5%2446%8%41%
1501
June1st to 15thNight
8%436%4235%49%47%
1320
16th to endNight
9%5%25%435%5%5%9%44%
1320
July1st to 15thNight
8%5%135%345%5%9%48%
1320
16th to endNight
5%325%4245%6%8%52%
1448
August1st to 15thNight
5%425%4335%49%51%
1485
16th to endNight
7%3244245%5%8%50%
1715
September1st to 15thNight
10%413424448%52%
1721
16th to endNight
11%32443335%7%50%
1815
October1st to 15thNight
12%42443335%7%49%
1826
16th to endNight
18%6%36%424345%39%
2260
November1st to 15thNight
13%7%3441335%6%45%
2276
16th to endNight
19%10%46%5%34346%31%
2340
December1st to 15thNight
21%12%6%8%6%3334425%
2387
16th to endNight
23%16%5%8%6%3333419%
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
65%311%12%6%
1433
16th to endDay
65%412%12%4
1587
February1st to 15thDay
63%39%14%7%
1716
16th to endDay
59%5%13%17%4
1580
March1st to 15thDay
58%5%12%16%6%
1827
16th to endDay
52%5%15%19%41
2154
April1st to 15thDay
50%412%20%11%
2151
16th to endDay
47%5%11%19%10%5%
2236
May1st to 15thDay
55%8%11%16%7%
2136
16th to endDay
42%9%12%20%13%2
2262
June1st to 15thDay
42%6%11%23%14%2
2310
16th to endDay
38%8%14%19%15%2
2310
July1st to 15thDay
38%7%11%21%17%2
2161
16th to endDay
35%10%18%23%11%2
2247
August1st to 15thDay
34%8%14%24%17%1
2132
16th to endDay
35%9%12%20%15%5%
2132
September1st to 15thDay
38%6%11%21%18%4
1898
16th to endDay
37%410%23%21%1
1815
October1st to 15thDay
40%6%10%23%17%2
1804
16th to endDay
48%412%23%11%
1610
November1st to 15thDay
38%412%22%19%2
1582
16th to endDay
57%412%18%6%
1620
December1st to 15thDay
65%5%10%15%3
1571
16th to endDay
68%5%9%12%3
1536
January1st to 15thNight
62%38%14%9%
2506
16th to endNight
61%412%14%6%
2635
February1st to 15thNight
57%413%15%7%
2145
16th to endNight
56%411%18%7%
1893
March1st to 15thNight
53%5%11%18%8%1
2133
16th to endNight
50%5%12%22%7%1
2079
April1st to 15thNight
47%6%10%22%12%1
1797
16th to endNight
41%5%11%21%13%5%
1635
May1st to 15thNight
51%5%12%20%9%
1485
16th to endNight
39%7%12%22%14%4
1503
June1st to 15thNight
33%6%11%27%19%1
1320
16th to endNight
35%8%14%21%15%4
1320
July1st to 15thNight
34%6%12%22%20%3
1240
16th to endNight
26%7%17%28%16%3
1348
August1st to 15thNight
30%5%15%21%23%2
1474
16th to endNight
30%6%13%24%19%5%
1715
September1st to 15thNight
29%6%11%23%22%5%
1721
16th to endNight
33%5%9%23%24%3
1815
October1st to 15thNight
34%5%11%25%22%1
1826
16th to endNight
46%49%26%11%1
2260
November1st to 15thNight
38%49%24%20%3
2276
16th to endNight
54%411%21%8%
2340
December1st to 15thNight
62%410%14%7%
2387
16th to endNight
68%5%8%12%4
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
31%14%36%8%7%1
90
16th to endDay
25%15%40%15%3
96
February1st to 15thDay
21%18%45%11%3
90
16th to endDay
16%16%41%16%8%1
81
March1st to 15thDay
33%14%31%16%3
117
16th to endDay
27%9%30%21%9%1
288
April1st to 15thDay
24%11%29%22%11%1
270
16th to endDay
17%7%32%20%16%6%
254
May1st to 15thDay
27%6%25%24%10%5%
228
16th to endDay
14%325%26%18%11%
302
June1st to 15thDay
14%327%30%17%6%
420
16th to endDay
13%5%24%28%19%7%
420
July1st to 15thDay
14%321%27%21%12%
400
16th to endDay
7%112%33%28%16%
396
August1st to 15thDay
10%8%25%31%22%
253
16th to endDay
10%114%19%37%17%
268
September1st to 15thDay
11%211%23%36%13%
255
16th to endDay
16%316%19%33%10%
254
October1st to 15thDay
12%6%21%30%19%8%
255
16th to endDay
23%9%35%27%4
122
November1st to 15thDay
11%8%23%22%26%7%
90
16th to endDay
28%8%42%15%4
90
December1st to 15thDay
24%15%35%17%6%
90
16th to endDay
22%21%46%6%2
96
January1st to 15thNight
26%15%35%18%3
900
16th to endNight
22%14%35%23%3
907
February1st to 15thNight
22%12%35%25%3
704
16th to endNight
21%11%37%25%4
631
March1st to 15thNight
21%13%31%26%6%
720
16th to endNight
20%8%35%25%7%1
735
April1st to 15thNight
19%9%34%30%6%
539
16th to endNight
22%5%32%26%11%1
528
May1st to 15thNight
24%426%32%11%
495
16th to endNight
13%222%37%20%2
515
June1st to 15thNight
10%222%45%18%
495
16th to endNight
11%119%40%25%1
495
July1st to 15thNight
11%116%40%27%1
465
16th to endNight
6%12%38%36%4
522
August1st to 15thNight
6%14%41%30%5%
494
16th to endNight
7%113%32%38%7%
525
September1st to 15thNight
13%213%34%30%5%
566
16th to endNight
13%315%33%30%4
657
October1st to 15thNight
14%5%22%33%19%4
660
16th to endNight
21%11%32%24%9%
704
November1st to 15thNight
17%9%32%26%12%1
700
16th to endNight
26%12%29%22%8%
720
December1st to 15thNight
28%11%32%20%6%1
767
16th to endNight
31%11%31%19%4
960
Page generated at 2017-04-27 17:49:00. Version ac04

Copyright 2017 A. Danko


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